The Nikon D850 has a focus-shift shooting feature, but they provide no concrete information about how much of a “Focus step width” to use. Instead, they only give you a step-size to select, ranging from 1 (small steps) to 10 (big steps). 105mm Micro Nikkor at f/8.0 15 stacked shots, shift 6, 0.4X For a shot like the kangaroo paw above, how do you determine what focus-shift step size to use? How do you determine how many shots to stack? What aperture should you use? If you have ever tried a macro shot with the level of magnification like this photo, you know that you can’t get this much depth of focus with a single shot. Before you go out into the field to shoot macro subjects, it would be worth your time to know to configure your camera and lens. The following article shows you how to calibrate your focus-shift shooting for an optimum shift step-size. The Focus shift shooting menu D850, 105mm Micro Nikkor, and LED ring light I used the gear shown above to take the close-up shots for the photos that follow. The battery-powered LED ring light provides really excellent shadow-less illumination. This setup works well even at 1.0X magnification. A tripod isn’t strictly necessary at long focus distances to do focus-stacking, but it (or some other camera support) certainly is required at high magnifications. You should use the “Silent photography” setting whenever possible, to minimize vibrations. I did some testing with my Micro Nikkor 105mm f/2.8 lens on the D850 to dig a little deeper into these “Focus step widths”. It turns out that those Nikon engineers did some pretty smart engineering. Although focus-shift shooting can be done with any autofocus Nikon lens at any distance, the main reason for this camera feature is for macro photography. Focus depth is incredibly small at high image magnifications, and most subjects turn out to be very disappointing with only a miniscule region in sharp focus. Nikon partially fixed this narrow-focus-depth problem with the ability to take a requested number of shots while automatically changing the focus slightly between shots. A problem arises with the “slight” focus change you want to specify to the camera. When you change lenses and/or apertures, the amount of focus change is different with every combination. To some degree, Nikon simply punted and came up with a dimensionless step value that you can request. Nikon only partially fixed the shallow-focus problem, because they don’t actually stack the photos. I’ll discuss later in the article how that problem can be rectified. 10 Stacked photos, Micro Nikkor 105mm at f/8, 1X It’s hard to believe, but the shot above is actually a stack of 10 photos. The smallest divisions on the ruler are actually 1/100”. This means that the region in focus is about 0.15 inches (3.8 mm) along the ruler. Since this is a stack of 10 shots, a single shot has only about 0.015 inches in focus! The ruler was rotated to 70 degrees, so the actual focus depth is even a little less. The combined stacked shots above, shot at f/8 with the Micro Nikkor 105mm, are at life-size magnification. Now, try to imagine if the lens focused down to maybe 2X magnification; almost nothing would be in focus. I chose f/8, since it’s the best combination of focus depth and resolution. The f/8 I mention throughout this article is the infinity-setting f/8, and it doesn’t take into account the increasing f-number as magnification increases. Micro Nikkor 105mm at f/8, 1X single frame The shot above is a single frame taken with the Micro Nikkor 105mm at f/8 and 1X magnification. There’s almost no depth of focus at all! Now you see why focus stacking is gaining in popularity. I did a number of tests to find out how much the focus-shift “step size” should be to guarantee focus overlap, but not to overlap focus any more than necessary. With the 105mm at f/8 at this focus distance, the largest focus step width size that would still have a frame-to-frame focus overlap was 7. If I stepped larger than that value, then I was left with unacceptable bands of out-of-focus in the stacked photo. If there was any wiggle in the camera or subject, I once again had a ruined shot stack. I determined that the optimal step size for life-size magnification with the 105mm at f/8 is 6. This gives a very slight safety margin for vibrations or image movement. I used a tripod for all of my testing, so the Silent photography is a great option to minimize vibrations. If you try hand-holding shots instead, turn the Silent photography option off (always use a tripod or some other device to help steady your camera for really close shots). After I had my desired test settings, I just pressed the “Start” option to begin automatically shooting the series of shots. After a brief “Processing” message, the D850 would then take the series of shots.You can also press the center button on the multi-selector to start shooting, once "Start" is highlighted. 10 Stacked photos, Micro Nikkor 105mm at f/8, 0.5X My next set of testing was conducted at 0.5X magnification, with the same 105mm at f/8. Guess what? The optimal step size was 6 again! Stacking 10 shots, the range shown in focus on the ruler was about 0.65 inches, or 0.065 inches per shot. This shows that the depth of focus went up by more than 4X at half-life-size, compared to life-size. For typical subjects, you’d probably want to stack more than 10 shots at this magnification and f-stop. All that you would need to do is increase the “No. of shots” in the menu to maybe 20 or 30. Micro Nikkor 105mm at f/8, 0.5X, single frame I’m showing a single shot at 0.5X magnification above, using the 105mm at f/8. This single shot still isn’t enough to focus the width of most bugs, but the stacked shot of 10 would have been just fine. 10 Stacked photos, Micro Nikkor 105mm at f/8, 0.25X Switching to 0.25X magnification, my testing showed that the optimal focus shift step size should be 6 once again. Simply amazing! Those Nikon engineers designed a system where a single focus shift step size would work at that whole range of distances! At 0.25X magnification, the 10 stacked shots above now shows an in-focus range on the ruler of about 2.5 inches. The depth of focus for the 105mm at f/8 for 10 stacked shots is getting into a really useful range for many subjects. Micro Nikkor 105mm at f/8, 0.25X, single frame Even at 0.25X magnification and f/8, the depth of focus is still too shallow to be very useful for this 105mm without focus stacking. Micro Nikkor 105mm f/8, 1/10X through infinity For testing something on the scale of landscape photos, you could extend my concept to use a subject like a fence. This would make it easy to evaluate shot-to-shot focus overlap. When you take the shots, the camera will simply stop shooting once it reaches infinity focus (or the end of focus travel), so you don’t have to worry about requesting too many shots in the sequence. Unsurprisingly, the same focus step shift size of 6 worked yet again for f/8. This stack took 29 shots to cover 1/10X through infinity. The camera took a few extra shots beyond infinity, stopping when it got to the end of focus travel. Remember to delete these “beyond infinity” shots before focus-stacking! This shot above demonstrates a major weakness of stacking shots for a landscape: wind. You can see some little ghost branches, etc. It’s a cold reality that you’ll usually end up using things like a healing brush in your editor when stacking shots from the outdoors. Micro Nikkor 105mm f/8, 1/10X. First shot of stack Until you see individual frames from a focus stack, it’s hard to appreciate how much focus depth can be obtained. It’s kind of like getting cataract surgery. How I stacked the test shots I used the free CombineZP program, created by Alan Hadley, to stack all of the shots shown in this article. I used Windows10; you’re out of luck on Apple computers. Something like Helicon Focus (not free) should work on Apple systems. Before the D850 “Focus shift shooting” feature existed, I used my Nikon PB-4 bellows for macro focus stack shooting. In that case, each photo was shot at exactly the same magnification. Using the D850 focus-shift shooting, the photos need to get “scaled” to be the same magnification. The CombineZP program has a few different macros that can solve this ‘magnification change’ problem. If you choose DX mode shooting versus FX mode, you’ll find that the stacking process is maybe 4X faster. Also, CombineZP sometimes has problems with full-size FX images in the TIF format, which changing to DX mode solves. Align (and scale) the shot stack in CombineZP To make a stacked shot, there are basically 6 steps I followed. 1 Convert the raw shots into TIFF format. (I use 16-bit) 2 Open the shots in the CombineZP program 3 Run the Align and Balance Used Frames (Quick) Macro 4 Run the Do Weighted Average Macro 5 Draw a rectangle around the finished stacked shot to trim it 6 Save the rectangle in jpeg (or TIFF) format Because the D850 does focus-shift shooting to create the photos to stack, each focus distance change causes a different magnification. If you merely combined the shots into a stack, none of the shots would match each other in size. The CombineZP program can fix this “scaling” problem, and simultaneously align the shots as well. The CombineZP program doesn’t understand the D850 raw photo format, so I use the free Nikon Capture NX-D program “batch process” feature to easily convert the shots into TIFF format. There are several stacking macros to choose from in this program; you can simply try another macro (or all of them) to see which one you prefer. Thank you Alan Hadley for this excellent program! I do have to mention that the CombineZP program can save images in TIF format, but some of my other editing programs don’t like those files; that’s why I recommend that you additionally save into jpg format, just in case. At least try out your favorite image editor with a file saved as TIF from CombineZP to verify it works okay. By the way, I run the CombineZP program under 64-bit Windows 10. There are other stacking program offerings out there, but I can’t comment on their relative ease or capabilities. You’ll need some other stacking software, such as Helicon Focus for Apple products. Summary For any given lens and f-stop, it’s pretty straightforward to take a series of focus-shifted shots using the Nikon D850 to find an optimal step size. By looking at neighboring shots afterward at 100% magnification, it’s easy to see if the shots share a common zone of focus. If the shots are shifted too much, simply decrease the shift step size and try shooting again. Once you have a “calibrated” step width for your lens and f/stop, it simply becomes a set-and-forget scenario. You can shoot with the confidence that your stacked shots should combine perfectly. If the last shifted photo hasn’t yet gotten enough of your subject into focus, then you can simply command the focus-shift “Start” option again, and the D850 will pick up focus where it left off. You can always increase the total number of shots to take, especially if your estimate was way too low to cover the whole subject. Focus stacking is pretty slow, so you want to minimize how many shots you try to stack. You will find it much easier and quicker to take shots at a lesser magnification (e.g. 0.5X instead of 1.0X) and simply crop the final stacked photo. The D850 has such high resolution that cropping is almost never a problem. If you’re lucky enough to have the 105mm Micro Nikkor, it’s very, very sharp. If you change your shooting to the DX crop mode, the stacking will be much faster, and it will take a fraction of the disk space. I’m amazed that the Nikon engineers designed a “Focus step width” algorithm that would allow a single setting to work with this 105mm lens at any distance for a given f/stop. This feature is going to revolutionize macro photography, which has historically been a very slow and tedious chore. 105mm Micro Nikkor f/8 shift=6, 12 shots, DX mode, 0.25X I tend to use my LED ring light with my macro photos instead of a flash. I really like how smooth the lighting results are, compared to flash.

The upper-end Nikons DSLRs, such as the D6, D850, and D500 have some pretty confusing jargon for their autofocus configuration. The enthusiast Nikon camera focus jargon is perhaps even worse. Nikon’s menu option descriptions tend to keep people from getting the best performance from their cameras. This article explains how I set up my cameras to optimize autofocus, and why. Keep in mind that your camera might be waiting around for a cheap/old lens to respond to its focus commands. To properly evaluate the following suggestions, you will need to select a lens that can “keep up” with your camera. Don’t blame your camera for something that your lens can’t do. And for heaven’s sake, do your testing in sufficient light. In all the tests that follow, I just used the center (cross-type) focus point. My test setup is plenty challenging without introducing off-center focus point comparisons. AF-ON Button (pro-level Nikons) First things first: set up your camera to strictly focus using the “AF-ON” button via your thumb for phase-detect photography. If you have stayed with the shutter button half-press to focus, you need to get over it. Pressing a button with your thumb to focus is simply superior. And stick with continuous autofocus (AF-C); single-focus is totally pointless after you configure your AF-ON button. It should take less than 5 minutes to fall in love with the AF-ON button. Configure your AF-On button You can configure the “AF-ON” button under the “Custom Settings” (pencil) menu, “Controls”, “Custom control assignment”. Specialize the AF-ON button I like to assign both “AF-area mode” and “AF-ON” to my button, and typically assign “D25”. Note in the screen above I have also assigned AF-ON to my depth of field preview (Pv) button with group-area focus. The joystick center button is additionally assigned AF-ON with single-point focus. Where to combine the AF mode with the AF button The dynamic-area focus option prioritizes distant subjects, while the group-area focus option prioritizes the nearest subject. I have a total of three buttons assigned focus duty, with three different ways to autofocus. AF-C Priority Selection Since it’s settled that you should stick with using the AF-ON button for focus (right??), the next setting is the AF-C priority selection: stick with “release priority”. The camera won’t stop you from taking the shot in release-priority mode. If you set the “focus priority” instead, the camera won’t let you take the shot unless it decides the subject is sharp enough. You want to be making this decision yourself and not the camera. Digital is cheap; you can delete the shot later if it’s really out of focus. AF Activation Make sure you make this AF-ON only. Don’t let the shutter button mess with focusing any more. Focus Tracking with Lock-On The Nikon “Custom Settings” (pencil) menu is where you configure autofocus “logic”, which they call Focus tracking with Lock-on. Where to assign the autofocus logic Block shot response ‘Delayed’, motion ‘Steady’ The first topic here is the option “Blocked shot AF response”. I equate this feature to “attention span”. The settings for this option range from “Quick (1)” to “Delayed (5)”. I always leave mine on “Delayed” or 5. With the “Quick” setting, if your subject escapes outside of your collection of focus points, such as the 25 points in “D25”, then your camera will immediately focus on whatever random subject is presently under the middle focus point. This is nearly always bad. If you have your camera “blocked shot AF response” set to “Delayed” or 5, then you’re given some grace time to re-locate your subject and get it back inside your focus point collection. If you can successfully re-locate the subject in time, then your subject focus-tracking simply resumes. This is good. This also assumes you’re pressing the “AF-ON” button the whole time. If you are busy tracking your subject and suddenly notice Bigfoot walking in the background, then all you have to do is briefly stop pressing the AF-ON button and then re-press it after centering your focus sensor over Bigfoot. You have become the master over your attention span, and are no longer at the mercy of your camera. Your camera will now immediately start tracking Bigfoot and forget all about the old subject it was tracking. This is good. I know that people want their focus system to be purely automated, but forcing you to control the “AF-ON” button will get you superior results compared to using the “Quick” blocked-shot response. The second topic here is the option “Subject motion”. The settings range from “Erratic” to “Steady”, and are just beneath the ‘Blocked shot AF response’. Now, you’d think that “Steady” would mean slow, versus “Erratic” meaning fast or quick. After many tests tracking subjects coming straight at the camera, I have found that “Steady” gives slightly more reliable results, and it seems plenty fast, too. This subject motion option means toward/away from the camera. I found that the “Erratic” setting tended to exhibit some focus hesitation or hiccups while tracking subjects moving toward me. The “Steady” setting almost never did, until light levels got too low. I couldn’t find meaningful differences in the speed of focus ability between the two modes. Before I ever tested this configuration, I had assumed that “Erratic” would obviously win for focus speed, but the testing results forced me to change my mind. How I test Focus Tracking I have done lots of tests with a setup that lets me look at frame-to-frame sharpness and also overall lens focus scale behavior during shooting. My tests let me vary the subject speed and light levels. Low-elevation shooting My setup includes using a tripod with a reversed center column holding a lens that has a tripod ring. This hardware lets me rotate the camera into any orientation and keep very low to the ground, so that my (short) moving target comes straight at the camera. Rotating with the tripod ring lets me see the lens focus scale (to record video of its motion). The setup above is testing a Nikon D500 with the Sigma 70-200 f/2.8 Sport lens. This is a very quick-focusing lens, which should be able to keep up with the camera. I use a second camera to record video at 120fps while being pointed at the Sigma’s lens focus scale. The video camera uses a wired remote to let me easily trigger recording start/stop. The video lets me closely analyze how the lens focus can hesitate and even exhibit forward/reverse/forward hiccups while tracking a moving subject. This focus action is faster than what people can follow, but reviewing the high-speed video after the fact makes it easy to analyze. Movie mode: assign the shutter release to record movies To enable my wired remote release to start/stop recording video, I have to assign the shutter release to record video as shown above. This only reassigns the shutter button functionality while in video mode. My moving target My moving target with a better focus target on its face To track focus, I get my helper to pull the toy straight at the camera at different speeds and in different light levels. I start the video recording (of the lens focus scale) and then start high-speed shooting (10 fps) as the target gets pulled toward my camera. The flat target on the toy’s face makes it easy for the camera to track the subject. I don’t want to use an ambiguous target distance that will just muddy the results. Before you snicker too much about using this toy target, read on. There’s method to my madness. With this rig, I get to monitor the resolution of each frame to evaluate the quality of focus. I know the exact distances involved, to calculate just how fast the subject is moving (using 10 frames per second shooting), and the video of the focus scale lets me review the smoothness of the lens focus tracking action. Lenses have to work much harder to focus at close distances, because they have to move their glass over larger distances inside the lens. My little tracking rig really stresses the camera focus capabilities, compared to distant subjects. Focus errors are much more obvious at close distances, too. My tests started at about 14 feet from the subject and finished at 4 feet (the minimum focus distance for this lens). The focus system has to work very hard in this scenario, due to moving the internal lens elements so far and also because of the percent distance change to the subject. Because of this, the target doesn’t have to move at blinding speeds (it was moving typically at about 6 feet per second). The depth of focus (135mm f/2.8) at 14 feet is 0.53 feet and it narrows down to just 0.04 feet (12mm) at the 4-foot-away finishing distance. Performing autofocus tests at long distances isn’t nearly as stressful for a camera or the lens. Depth of focus is relatively huge and the internal lens elements have to be moved much less to track the subject. For distance testing, your subject has to move at very high speeds to be as challenging as doing close-up testing. Shooting with this D500 at light levels down to EV 5.9 I didn’t see any slowdown in focus tracking, compared to bright light levels. The “Erratic” subject motion setting had more focus failures than the “Steady” setting did, although it generally recovered focus within 1/10 second (I didn’t get 2 frames in a row out of focus at 10 fps). The differences I noted between Erratic/Steady are subtle. To be honest, I would be hard-pressed to guess at which “Subject motion” setting was being used by conducting these tests. There just wasn’t that much of a difference; both settings generally produced excellent responses that went well beyond my initial expectations. I’d be wary of reviewers claiming obvious differences between the “Subject motion” settings without knowing just how controlled their focus-tracking tests were. Enthusiast Nikons For Nikons like the D610 and the D7000-series (and the current Z cameras), the focus tracking configuration options decrease. You can still assign a button (AE-L AF-L) to give you “AF-ON”, which should be your first priority. Again, stick with AF-C focus. Focus configuration Nikon D610 To adjust the camera’s response to a moving subject, you need to select the “Focus tracking with lock-on” option. Quick subject distance change response is ‘Short’ (1) There isn’t a pair of configuration options like the pro-level Nikons provide. Instead, the options are reduced to a single selection. The Nikon explanation isn’t entirely helpful. Nikon’s focus help The explanation above indicates that you would like to set it to “Short” to quickly react to something coming toward you or away from you. So far, so good. You need to select “Long” to prevent re-focus if you briefly have your subject get outside of your focus point collection (the same as ‘blocked’). The “help” also indicates you need to turn this option off altogether if you are switching between subjects at different distances. (Remember my discussion above about assigning “AF-ON” to a button so that you can handle this task?) These two Nikon explanations are at odds with each other. You really want both quick response to subject distance changes and slow response to re-focus if you briefly lose the subject from your focus point collection (side-to-side motion). Since you can’t have both, I feel the best compromise is the “1 Short” choice. You want the camera to react quickly if your subject suddenly comes towards you or away from you. This choice is a higher priority than having the camera give you a longer grace period to re-acquire your subject. You’re now faced with the added pressure to never let your subject get outside of your focus point collection. You can, of course, change to a larger dynamic area (number of focus points in your collection) to lessen the chance of having the subject escape outside of the focus point box. Now you can see why the ‘pro’ cameras give you a pair of choices for the autofocus logic. After lots of tests using a D610, I am more convinced than ever that it should be relegated to landscape photography. It was woefully inadequate at tracking focus in my tests, unless the target was moving fairly slowly. It didn’t matter which “Focus tracking with lock-on” values I chose; it seemed equally inept at any setting. The contrast to tests done with the D850/D500 was stark, and really makes me appreciate the pro-level autofocus that those cameras possess. My D7100 consistently seems more adept at autofocus than the D610, even though the two cameras are supposed to be roughly equal at autofocus, and they both sport the Expeed 3 processor. My little focus test toy was just too much for the D610 to cope with. I realize I’m overreacting to the D610 results. I just remember the high percentage of lost shots of moving animals and how frustrating that was. My D500 and D850 are so far above its focus capabilities, it’s hard to believe they were all made by the same manufacturer. Conclusion People have very strong opinions when it comes to autofocus. Rather than taking my suggestions at face value, I’d suggest you try some tests on your own. While pressing the AF-ON, try panning your camera off and then back on a static subject to get a feel for the focus “attention span” duration. As you may have inferred, it’s much trickier to evaluate near/far focus behavior. I always try to show how you test something, and not just give you "results" or opinions or regurgitate marketing literature. There are so many elements that go into autofocus results (including practice). To me, this is the most complicated aspect of mastering a camera. The camera models that let you assign different autofocus modes to different buttons are golden, but you still have to train yourself to use them I can’t stress enough that you need to get comfortable with using the AF-ON button (or an assigned button for this purpose). Use your thumb to control when to focus on a different subject; don’t get trapped into the notion that you have to wait for your camera to decide when to refocus on a new target.

I submit for your approval (as Rod Serling used to say) the Neewer R-160S LED ring light. I’d like to bring to your attention a battery-powered LED ring light that was designed for macro photography. The first thing I did after I got it, of course, was to try to misuse this light for portrait photography with an unanticipated lens (the Nikkor 85mm f/1.4). I have used an LED ring light for my macro photography for many years. This particular LED is built like a tank out of anodized aluminum and has to be powered from a voltage supply plugged into a wall socket. To attach this light, there are three tightening screws to press against the macro lens barrel. It’s very limited in which lenses it can be used with, and you have to stay relatively near to a wall socket. The Neewer LED ring light is none of these things. Which is why I got it. It’s really light, portable, and all plastic. Come to think of it, though, how many flashes are made out of metal? Neewer R-160S and Micro Nikkor 105mm f/2.8 on D850 The Neewer LED R-160S is powered by 6 AA batteries (I use rechargeable batteries). It, in fact, comes with a little adapter plug that can be used with an external DC power supply (6-17 volts) that I will never use. The 6 “flower petals” around the ring light house the 6 AA batteries in little slide-open drawers. The Neewer LED is pure plastic (for light weight) and has 160 dimmable LEDs (100% through 10%) that have an advertised color temperature of 5600 Kelvin. It produces up to 1200 Lumens (more than enough power at full output to make models quite angry with you). Little +/- buttons on the rear of the unit control the brightness. Press “-“ before pointing it at a model. This ring light can be mounted three ways: onto your lens filter thread, onto the camera hotshoe, and onto a tripod. The hotshoe/tripod attachment is also included. Its light is specified to cover 45 degrees. I have only tried it on 35, 50, 85, and 105mm lenses so far. Forget 35mm; edges were dark. At 50mm with longer focus distances, you’ll need to fix edges being dimmer with your photo editor; macro range lighting is fine. Illumination is perfect corner-to-corner with lenses longer than 50mm. The provided (anodized aluminum) filter thread attachments come in 49mm/52mm/55mm/62mm/67mm sizes. Personally, I just use the largest provided 67mm adapter and then attach it to either my step-up or step-down rings to use it with my lenses ranging from 52mm to through 77mm filter threads. And now for the bad news. Here’s why I bet at least half of these lights will get returned for a refund: the inner ring lights shine directly into your lens! This is a glaring design faux pas (pun intended). This problem took maybe 2 seconds to discover after I turned on the ring light after mounting it onto my Nikkor 85mm f/1.4 lens. It took maybe another 10 seconds to figure out a cheap and quick fix for this inner-light flare problem. All I had to do was spray black paint over the inner portion of the ring light. For extra credit, you could first spray the inner ring with silver paint and then give it a second coat of black paint. The silver paint would reflect the light back out to your subject, and the black paint coat acts like a lens hood. The finished product is shown in the shot at the top of this article. Neewer light out-of-the-box condition In the shot above, you can see that the inner portion of the ring light is just transparent plastic, lined by many LEDs. This inner portion of lights causes massive lens flare, since the LEDs shine directly into most lenses! What were the designers thinking??? For macro lenses with a deeply-recessed front element, this inner-circle light probably wouldn’t be a problem, and you could leave the ring light unpainted. If you tried using a reverse adapter on the lens, however, this flare problem will really bite you. Some painter’s tape masking I traced and then cut out a circle of painter’s tape to put over the outside of the ring light. I also masked further back where my fingers are seen. Just the inner portion of the ring light is exposed before unleashing the (plastic-compatible) spray paint. Ring light after two coats of black spray paint The shot above shows the ring light post-spraying. After the first coat, I turned on the ring light and discovered that light was still getting through the paint. Those LEDs are really powerful. Two coats of paint stopped any light leaks. Problem solved. As I mentioned earlier, I wanted to see if this ring light would work with my Nikkor 85mm f/1.4 lens (filter thread 77mm). Before the paint spraying, this combination was a disaster of light flare. Tripod/Hotshoe mount is included You can mount this light above your camera onto its hotshoe, if you wish. You can also mount it onto a tripod with an attachment that can pivot to aim the light. I’d be careful with this attachment, since it didn’t seem very robust. Nikkor 85mm f/1.4 with 77-72, 72-67 step-down rings Shown above, I attached a pair of step-down rings to connect my Nikkor 85mm f/1.4 lens onto the Neewer’s 67mm attachment ring. The 85mm lens has a 77mm filter size. To test how this combination would work, I photographed a blank wall at f/1.4 and saw NO corners cut off and the shot was evenly illuminated. And zero flare from the ring light. Stopping down the lens, the illumination got even better, since the 85 has a fair amount of built-in vignetting when shot wide-open. 85mm f/1.4 with Neewer LED ring light mounted onto the lens The ring light works really well as both a primary and a fill light. Compared to a flash (even with most flash diffusers) the light is just so smooth. Shown above, the light was used to fill the shadows. It’s so nice to see the lighting before the shot instead of after the fact when using a regular flash unit. Note the neutral-gray vase shown above stayed neutral using this light. 105mm f/2.8 Micro Nikkor with Neewer ring light The sunflower was lit entirely by the ring light. It just looks different than using a flash. Focusing is really easy, compared to using a flash. The ring light makes shots look more like they were done in a studio, and they don’t scream “flash”. Macro shot from 15-shot focus stack using Neewer LED light The macro shot above (105mm Micro Nikkor at f/8) at about 0.25X magnification is made from 15 stacked shots. I used the Neewer LED light to provide much more even lighting than a regular flash would have provided. In times past, I would have had to use a different lens to get this shot, because my metal riing light wouldn't fit onto the 105mm Micro Nikkor. In addition, I didn't have to bother with any power cables. Conclusion I bought this light to use for macro photography, so that I won’t have to be tied to a wall outlet anymore with my old ring light. After trying this for more general-purpose photography, I’ve decided it’s going to also get used for portraits; the lighting really minimizes wrinkles. If you haven’t yet noticed, people don’t like their wrinkles showing any more than they have to. Reflections off of the eyes look good, too (no doughnuts). This Neewer R-160S LED ring light definitely isn’t built as robustly as my metal ring light is. I’m pretty careful with my equipment, so that’s not much of a concern for me. If you’re rough with equipment, then you probably shouldn’t get this light. If you are reasonably careful with your equipment, I think that this light can be really useful. If you’re not up to the challenge of a little spray painting project, then you probably won’t be happy with it.

The Movo gimbal head is the perfect partner for your big telephoto lens. It’s essentially identical to the well-regarded Wimberley WH-200 gimbal head II, for a fraction of the price. I’m not trying to sell these Movo gimbals, but I thought you should know. If you feel that your reputation would be ruined if somebody sees “MOVO” on your gimbal, then consider buying the Wimberley instead. Gimbal heads are designed to let you easily track moving subjects with the lightest of a touch. All of the weight is supported by your tripod or monopod, so you don’t experience any fatigue trying to hold large and heavy telephoto lenses. You really don’t need a gimbal for small, light lenses; if your lens doesn’t have a tripod foot, then don’t use a gimbal. Gimbals in some ways operate the opposite of a conventional tripod head or a ball-head. You could face a nightmare if you loosen a ball-head and then let go of your camera with a heavy lens on it, causing it to instantly flop to the side. With a gimbal, after you loosen its tilt/pan knobs and let go of your camera, nothing happens! Movo GH-700 Gimbal Head US $100.00 The Movo GH-700 gimbal has a 30 pound load limit, which should be enough for virtually any lens/camera combination that you would ever put on it. It comes with an Arca-Swiss lens mount. The gimbal weighs 3.1 pounds (1.4KG). It’s about 10 inches tall and 10 inches wide, which is necessary to accommodate big-diameter telephotos. As is always the case, this means you need to get an Arca-swiss plate to put on the tripod foot of any Nikkor telephoto. You can find carbon-fiber gimbals to save some weight, but they’re pricey. Wimberley WH-200 Gimbal Head II US $595.00 If you can tell the difference between the Movo and the Wimberley gimbal, aside from the Movo giving you a marked height scale on it, then you have better eyes than me. I’m not saying the Wimberley is inferior in any way, I’m just saying the Movo is an equivalent product for much less money. You should note that gimbal heads for still photography are different than gimbal heads for video. The Movo and Wimberley are for still photography. I almost always use my Movo gimbal on a Feisol carbon-fiber monopod (CM-1471), since it’s a much more mobile combination than using a tripod. This is an ideal wildlife photography rig. The gimbal has a 3/8” female tripod thread, instead of the more-common ¼-20 thread. If you prefer a tripod, it works equally on those, too. Gimbal heads enable you to perfectly balance your camera and big lens, so that it will maintain the position wherever you have aimed your lens when you let go of it. This balance makes for an ideal shooting situation, where your gear feels weightless and moves fluidly in any direction. You can follow subjects easily, because you can both pan and tilt the lens simultaneously. You can spend hours shooting with the heaviest of lenses and still not experience any arm fatigue. The main thing to tire you out is walking from one spot to another. I use a sturdy strap to connect my photo backpack to my monopod when I’m walking, so that the weight is transferred to my backpack across my chest. All of my big, heavy telephotos have an Arca-swiss mount, so they mount quickly and easily onto the gimbal. I have been using my Movo gimbal for over 5 years now, and it works as well as the day I got it. It’s all metal, except for the heavy-duty plastic knobs on it (the same as the Wimberley). This is one piece of gear you don’t need to pamper. Attach the Arca-swiss lens foot to the gimbal You can mount the lens onto the gimbal with the tilt knob either on the right or left side of the camera. I prefer to mount the lens so that the tilt knob is on the camera right-hand side (shutter button side). This lets me use my left hand to zoom and manually focus the lens without any obstructions. The gimbal itself works equally well in either mounting configuration. How to adjust the gimbal for proper balance Start by loosening the ‘Tilt knob’, so that the lens can easily tilt up and down while mounted on the gimbal. Loosen the ‘Height knob’ and (temporarily) lower the Arca-swiss lens platform to the bottom position. Get a good grip on your lens while doing this height adjustment, so that it doesn’t suddenly drop to the lowest position. You need to adjust the front-back balance of your camera and lens by sliding the lens foot along the Arca-swiss mount, just like you do when using a tripod head. With just this balance adjustment, the lens should come to rest in a horizontal position if you tilt it and then let it swing back. Lock the lens foot with the Arca-swiss knob after it is balanced. Tilt axis should intersect Lens axis You also need to adjust the height of the lens (loosen the ‘Height knob’), to make sure the ‘Lens Axis’ intersects the upper pivot point (‘Tilt Axis’) of the gimbal. On most lenses, the center of gravity is the same as the lens optical axis center. This vertical gimbal adjustment (locked with the Height knob) enables the camera/lens combination to stay in the same position as you let go of your camera, even when the Tilt tightening knob on the gimbal is loose. You may have to slightly raise or lower the lens height, depending upon the center of gravity of the lens, to achieve perfect balance. Now, you should be able to tilt the lens up or down and have it stay there after you let go of the lens. The Movo has a handy vertical scale on it, so that you can note the proper height for a given lens/camera combination. If you have other lenses that you use on the gimbal, you can then quickly adjust to the proper height for that combination using the scale. When properly balanced, you shouldn’t need to tighten the tilt axis knob. The tilt and pan only need to be locked when you want your camera/lens rigidly locked into position like on a conventional tripod head. You may find that with very light cameras on big lenses that you can’t slide the lens back far enough on the Arca-swiss mount to achieve balance. A camera battery grip can really help here, providing the needed extra weight to balance. A longer Arca-swiss plate on your lens tripod foot may help, unless it starts to hit the tripod/monopod when you tilt the lens on the gimbal. I suppose you could attach extra weights to the camera tripod socket, like metal plates or washers held with a ¼-20 bolt. Be aware that zooms can shift the front/back balance of the lens as you zoom. Try to balance your rig at your most-used zoom position. Shooting While shooting, you typically don’t need to tighten the tilt or pan knobs. I generally leave vibration reduction active on my lenses, since I’m still holding onto the camera. I don’t use the “panning” mode of vibration reduction, since both axes are usually in motion. If you mount the gimbal onto a tripod for static shooting, go ahead and tighten the tilt and pan knobs after aiming the lens. Balanced camera and lens Gimbal mounted on monopod Summary For the price, it would be hard to beat this gimbal. It’s rugged and very smooth in operation. It’s such a pleasure to be able to concentrate on shooting instead of struggling with the weight of a heavy telephoto. There’s a world of difference between using a conventional tripod head and the freedom of a gimbal. Once you use a gimbal, you’re going to want one.

If you love black and white photos as much as I do, then you should consider using Silver Efex Pro 2. This plug-in can convert your color photos into black and white with an extraordinary level of flexibility. Plug-ins like Silver Efex Pro 2 can be used in conjunction with many editing programs, and even stand-alone. I’ll be showing you how I use it starting from within Lightroom. There are many photographic subjects that simply aren’t enhanced by viewing them in color. Many subjects can be given a timeless quality by turning them into black and white. As a photographer, you should at least consider whether your subject might be made more special by a black and white transformation. So, what’s that reference to the Zone System? The Zone System was invented by Ansel Adams, and it subdivides the light levels of a photograph into ‘zones’, where each neighboring zone number differs by one f-stop of brightness. In Ansel Adams’ day, film and paper could capture about 9-stops of light at most. If you throw in total blackness (Zone 0) and total whiteness (Zone 10), the Zone system refers to 11 zones. Ansel created a system using these light levels to calibrate exposure, developing, and printing to control the results he wanted to get. Silver Efex Pro 2 includes the Zone System in their program. You can use it to see qualitatively how changes in presets, exposure, film emulation, highlights, shadows, contrast, etc. will place areas of your photos into these zones. If you do any inkjet printing, then you should know that any photo areas that land in zone 10 will not only be pure white, but they can also have a different “gloss” than the rest of the print, which generally means that the print is ruined. If you don’t use this Zone System for anything else, then use it for this problem as a sort of early warning system. You probably already know of this problem as “blown highlights”. Laser printers don’t suffer from this effect. Some newer inkjet printers actually have a ‘white’ ink, which also eliminates the ‘zone 10’ problem. Invoke Silver Efex Pro 2 from Lightroom As shown above, you can start up Silver Efex Pro 2 from Lightroom via the “Photo” menu, selecting “Photo | Edit In | Silver Efex Pro 2”. Editing options The editing dialog options before Silver Efex Pro 2 opens up allow you to decide if you want to modify the original or a copy, and you can also decide if you want to retain the edits you have already made. The Silver Efex Pro 2 main screen Silver Efex Pro 2 of course has the standard editing options to adjust highlights, shadows, contrast, etc. after making a ‘neutral’ conversion of your photograph into black and white. Besides being presented with a large list of preset styles (with thumbnail previews), you also have a sizeable library of film-type emulation, such as various Kodak, Agfa, and Ilford films. Under the heading of “Toning” (inside “Finishing Adjustments”), you also have the ability to adjust the hue/tone of the “silver” in the image (ala silver halide crystals of photo paper) and the “paper” hue/tone, as well. Sepia Toning #20 Another “Toning” feature is available if you click the little drop-down control next to the default “#1” neutral value just to the right of the “Toning” label. You will find options for all of the standard darkroom coloring chemicals, such as “Sepia” and the very toxic “Selenium”. You can adjust the strength of these effects, of course, using the slider just underneath the “Toning” label. The main talking point of this article (the Zone System) is fairly well hidden, however. To locate the Zone System features, you need to scroll down to the bottom of the right-hand menu and expand the “Loupe & Histogram” option. Place the mouse cursor into the Histogram plot area, and the little square ‘Zone’ icons with numbers (0 through 10) suddenly appear. If you hover the mouse cursor over any Zone number icon, you will see colored highlights appear in your photograph that represent that light value. Each zone number has a different highlight pattern/color to identify itself. Viewing “Zone 8” values in the photo The screen shot above shows what happens when you hover over the “Zone 8” icon. You get a red cross-hatched pattern over all areas that contain the Zone 8 light value. If you move the cursor away from the icon, the highlight pattern will disappear. If you click on one of the Zone icons, then the highlight pattern will stay on the photograph until you click that same Zone icon again. You can click on multiple icons, although the display gets confusing in a hurry. Once a Zone is selected, then moving a slider such as “Highlights” causes that Zone number pattern to dynamically change in the photo. Zone 0 shows up as yellow cross-hatching Since it’s usually visually important to have at least some of Zone 0 (total black) in most photos, leaving this Zone clicked while editing the photo is very common. It will help keep you from accidentally getting rid of all of the Zone 0 areas. It’s also very common to leave the ‘Zone 10’ icon clicked, in order to ensure that it never shows up in your photo unless you have something intentionally blown out like the sun or a specular reflection. Conclusion If you’re interested in black and white photography, then you really should try out Silver Efex Pro 2. Once you use it, I think you’ll find that general-purpose photo editors will disappoint you with their limited repertoire of black and white editing features. You’d swear that the author of this little plug-in must have worked in a darkroom. I for one sure don’t miss those nasty chemical smells, or having to maintain 20 degrees C.

If you take lens focus calibration seriously, then you might want to consider changing from mere visual inspection to doing it by the numbers. Computer analysis is far more discriminating than what people can accomplish via judging sharp focus by eye. Let your computer help you calibrate your focus Some newer cameras can focus-fine-tune using built-in features, but the results aren’t quite as precise as they can be. Estimating focus by using “slanted ruler” targets (or picket fences) will only typically get you within about 10 or 15% of optimal. I think it’s about time to describe in painstaking detail a method to get the best focus calibration possible. In many previous articles I mentioned the benefits of focus calibration, but I never went into much detail about the procedures to actually do it. I hope that this article will rectify that situation. I’m going to show you a technique that is incredibly accurate, but it will require a little bit more effort on your part. This procedure involves using the free software called MTFmapper. The same web site that offers this software also provides various focus target files (and resolution charts, too). Some cameras only let you choose a single focal length or focus distance for calibration; for these, you should pick your most-used lens settings for measurements. The Focus Target You need an excellent focus target of appropriate size to get the best results. If you have to get really close to a focus target, yet you always shoot subjects from much farther away, the results are sub-optimal. The focus target (from the MTFMapper site) The image above shows you what the target looks like after you have rotated it by 45 degrees, with the left-hand side farther away than the right-hand side. The bands of little squares appear to be constrained into the shape of a rectangle, but this is an optical illusion. They’re actually constrained into the shape of a trapezoid, where the left side is taller than the right side. The lens perspective distortion makes the trapezoid appear to be a rectangle (or nearly so). The red square shown above represents where you point your camera’s focus sensor. It needs to be over the large right-hand side edge of the big “target” rectangle. This makes for an easy, unambiguous focus target for your camera. There’s no doubt where your camera is trying to focus. Focus chart for shooting close The focus chart above is called “perspective_a0_distance_1500.pdf”. This chart would ideally be printed on “a0” size paper shot from 1500mm away. It’s an example of the many charts the MTFMapper site offers. Different lenses (e.g. telephoto, normal, wide-angle) can have vastly different perspective distortion. Because of this, the MTFMapper web site offers multiple target files that have different levels of distortion. You need to pick the target that most nearly matches the lens/distance being tested. If you shoot a target that has large perspective distortion trapezoids with a telephoto, some program analysis features will probably fail. The rotated targets in your viewfinder should look like rectangles when you properly match the target to the lens and focus distance. I sometimes grossly violate the recommended shooting distances/charts for focus testing (see below). Some software analysis features may be unavailable or limited if you do this. I make these violations to get more precise information about where the lens is focusing. You should print and mount the target(s) onto something like poster board or wood. I have different sizes of printed targets, depending on the lens being tested. I use spray-on adhesive to mount the paper target completely flat. Dry-mounting services at art stores work extremely well for mounting larger-sized prints. I make target prints out of both Laserjet and Inkjet. If you’re shooting in infrared, only Laserjet will work; inkjet inks are generally invisible to infrared. I have a range of printed focus targets from as small as 8 ½ by 11 inches to as large as 4 feet by 5 feet. This gives me a lot of options when calibrating anything from a super-wide to a long telephoto. My larger targets are properly framed and have proper mounting hardware, but I keep some targets un-framed and just temporarily tape them up for a quick test. Shooting the Target I mount my camera (or the lens) onto a heavy-duty tripod, and I use a bubble-level to make sure the camera is perfectly level, with the frame left/right edges perfectly vertical. It’s important to get your lens axis at the same elevation as your focus target center. The analysis software will indicate you have a proper setup by color-coding the measurements in yellow where it sees near-perfect verticals and horizontals (see the ‘annotated’ plots below). The other edges in the analysis will be labeled in cyan (typically edges that are slanted by about 5 degrees). The “little” target rectangles above and below the big rectangle should have cyan measurements on them, since they’re slanted at about 5 degrees. If you don’t get your camera and target properly leveled, then you will end up getting focus plane measurements that have a ‘tilt' to them, which makes for an ambiguous focus plane and confusing results (and will likely make the software unable to produce correct result plots). On many Nikons, you can use the “virtual horizon” to get your camera leveled pretty well. Make sure you have good illumination; you don’t want to make your camera have to hunt for focus. It’s important feedback that the large target rectangle resolution value displayed in the “annotated” plot is yellow and not cyan. Both the camera frame edge and the target large rectangle edge need to be vertical and parallel. The yellow color confirms this alignment. It’s unfortunate that you have to wait until you run the analysis program to see if the ‘annotated’ plots display this target edge measurement in yellow. Depending on your camera, you might get better results in you use about a +0.7 stop exposure compensation when shooting the chart. This will often get the white target background to look white; camera meters are still pretty easy to fool. I take multiple shots of this target, and I de-focus the lens between each test shot and force the camera to re-focus using continuous auto-focus. This simulates exactly how the camera will be used in “real” shooting conditions. Each shot will be focused slightly differently, due to natural camera focus variation, and I’m after the “average” focus distance. I like to use continuous-focus mode and a “single point” focus sensor; this is closest to my own shooting conditions for regular subjects. When I use long lenses, I leave vibration reduction active (the lens still shows a small amount of wiggle as I press the shutter). In the following example, I set up my focus chart at 48 feet (14.6m) and shot it at 600mm. I use the MTFMapper program to analyze the chart shots, so that I get very precise answers about what’s in focus and what’s not. I found out that yes, indeed the focus calibration was off. Not by a huge amount, but it was generally focusing too far by about an inch (25mm). The lens used in this example is the Sigma 150-600mm zoomed to 600mm. It lets me calibrate at multiple focal lengths and distances, so I’m testing the calibration combination of 600mm at 48 feet. A really small target to find small focus errors The target above is printed and mounted on an 8 ½ by 11 inch piece of poster board. I used spray-on adhesive to attach a Laser-jet print onto the board. It’s a very temporary setup, so I just used painter’s tape to hold the target against a wall. I used a bubble-level to ensure the target is mounted with the big central target rectangle vertical edge perfectly vertical. The target shown above is intentionally quite small in the frame. I’m testing a 600mm lens here, and I am looking for really small focus changes from really far away. The measurement software is so capable that this scenario works fine for analysis. Your own eyes aren’t good enough for this analysis task, but the software is. Again, the lens axis is rotated 45 degrees relative to the target face, with the target left side farther from the camera. This shot shows a pretty gross violation of the MTFMapper program expectations. The program expects a shot that mostly fills the frame and is at the specified distance (2.5 meters for this particular chart). Instead, the chart only fills a fraction of the frame and is shot from much, much farther away than the program expects. The software can actually analyze target rectangle edges down to about 40 pixels, but of course more pixels will give better results. For wide angle lenses, you wouldn’t want to have a target this small in the frame. The depth of focus on this kind of lens will be deeper and will have a more gradual sharpness change than for telephotos. You’ll want to print and mount as large of a target as you can reasonably make when testing this lens type. For large targets (my largest target is 4 by 5 feet) you’ll get the best results by mounting and hanging them like a large photograph. My large targets have conventional picture-hanging hardware on their backs. Analyzing the Focus Chart Photo The MTFMapper program can give you focus chart results in a variety of ways and in a variety of measurement units. To get my preferred “MTF50 lp/mm” resolution units, you need to set your program preferences to match your camera sensor pixel size (in microns). After the preferences are set/verified, run the focus analysis via the “File | Open” menu option in MTFMapper. Tell the program where your “raw” format photos of the focus chart reside. Set your camera sensor pixel size Access the Preferences dialog via the menu “Settings | Preferences” option. Note that both the “Profile” and “Annotation” options are also checked. MTFMapper ‘annotated’ plot screen selection The screen shot above is slightly zoomed in to show target measurement details. In this program, you can zoom in by holding down the Control key while using the mouse scroll wheel. Notice that the shot is transformed into black and white. Here’s your chance to verify that the big target rectangle right-hand side shows an MTF50 measurement displayed in yellow. If the measurement is cyan instead, you should realign the target and/or camera and try again. MTFMapper Profile plot screen The Profile plot is generated using the edge resolution measurements of rectangles from the focus chart shot. The vertical blue line represents the right-edge of the large target rectangle. This plot makes it easy to see where peak focus is located, relative to the blue target line. Focus target detail with MTF50 edge measurements The (cropped) shot above shows the center of my focus chart, shot at 600mm from 48 feet away. This is a screen shot of the “annotated” plot from the MTFMapper program. The numbers on the little black trapezoids are resolution measurements in units of MTF50 lp/mm. I always shoot in ‘raw’ format; measurements using jpeg files are vastly different. Again, the left side of this chart is farther from the camera than the right side, rotated by 45 degrees. I used phase-detect focus and aimed my focus sensor at the right-hand side of the large black rectangle (where it’s showing the yellow measurement of “43.8”). The highest resolution edges in this example are generally about 3 “little” rectangles to the left of the big rectangle right edge. This focus error is only about an inch along the lens axis. In this shot, the measurements that are displayed in yellow indicate that those edges are perfectly vertical or horizontal, versus the cyan-color measurements on edges having a slight slant to them. At this scale, your own eyes are incapable of discerning the edges with best focus with any degree of certainty. To the software, however, it’s easy and totally repeatable. Don’t place too much confidence in the MTF resolution numbers in this shot, since this isn’t a proper resolution-measuring plot, the target is only a small part of the image frame, and the target (on purpose) isn’t parallel to the image sensor. It’s fair to compare these resolution numbers to other shots taken in the same shooting conditions, however. I have larger focus targets than the one shown above, but focus targets with smaller rectangles (trapezoids, actually) give me a better idea of exactly where the best focus is located. The measurements show that best focus is further away from the vertical edge I aimed at, and I need to use a “-” focus calibration shift to get the lens to focus closer to the camera. The “large” rectangle is only 2 inches (50mm) tall, and I remind you that I’m shooting this from 48 feet away! My larger focus targets are generally to be used when I’m calibrating a wide-angle lens. Profile plot of target from MTFMapper The profile plot shown above makes it easier to see where the focus lands (at the green line peak). The blue line indicates where the right-hand side of the target rectangle edge is (where I pointed the camera focus point). Clearly, the lens is back-focusing. The little red dots represent each measured tiny rectangle edge resolution, and the green line is a smoothed plot of these measurement averages. The focus calibration fine-tune will require a (-) adjustment to pull its focus closer to the camera to fix this focus error. If you don’t have an accurate setup while shooting (or you mismatch the target perspective to the lens), the profile plot might fail to render properly; in those cases, you can just go by the “numbers” on the rectangle edges in the “annotated” plot results to judge where the best focus is, versus where the target vertical edge is. Note in the plot above that the intersection of the blue line and the green line has a resolution around 44, versus the green line peak of around 54, showing resolution loss of about 10 lp/mm at the desired focus plane. As I mentioned, these resolution numbers aren’t strictly reliable for this style of chart, but they’re at least representative of the loss in resolution. Who could have imagined that a focus miss of about an inch would result in such a big resolution loss on the intended target? It’s worth noting that some lenses (usually the super-fast lenses) can also shift focus with an aperture change. On these lenses, you need to set the desired aperture for calibration. On most lenses, you just need to set the widest aperture for testing. Sigma was a pioneer in the sophisticated lens focus calibration arena. They let you calibrate zooms with 16 different focal length/distance combinations. Tamron now provides a very similar calibration feature for their newer lenses. Canon typically only lets you calibrate at two focal lengths on their zooms, while Nikon only gives you a single fine-tune calibration setting (their D6 does allow a ‘wide’ and ‘telephoto’ calibration pair on zooms). Neither Canon nor Nikon let you save any calibration settings within the lens itself. The Sigma lens focus-fine-tune firmware (and also the Tamron firmware) is smart enough to interpolate all of the in-between calibration settings for the lens focal length and the focus distance. The 500mm calibration would be affected by both the 400mm and 600mm calibration values. Canon cameras that have two-calibration settings can also interpolate, but they have a lot less information to work with. Sigma Optimization Pro calibration settings As seen in the sample above, I now have an updated focus calibration for the 600mm setting at 48 feet (-6) and a new setting for the 400mm setting at 20 feet (-9). These two small tweaks got my Sigma perfectly focus-calibrated again at all focal lengths and distances. If you’re using a Nikon or Canon lens, you have to use the camera focus fine-tune to fix the problem instead of the lens firmware that Sigma/Tamron have. For my other Nikon cameras, I still have to set the single focus fine-tune value when I mount the Sigma onto them. I can pick any distance or focal length and then run through the same calibration procedures discussed above for that zoom/distance setting; all of (16) Sigma internal lens calibration settings will “go along for the ride”. Each of my cameras is a little different, so even with a calibrated Sigma lens on a different camera, it will still require me to enter the camera fine-tune setting, versus the internal Sigma fine-tune settings. Only the camera that I calibrated the Sigma internal fine-tune settings on will get a “0” camera internal fine-tune value; none of my cameras are calibrated exactly the same. Improved focus accuracy with new fine-tune calibration The shot above shows the analysis of the focus target using the new focus fine-tune calibration settings. The focus (and highest resolution measurements) is shifted back to the correct distance. You always need to take several shots and re-focus between each shot. There is a small shot-to-shot variation, and you need to determine where the “typical” focus lands. Profile plot with new fine-tune calibration You can see in the plot above how focus has shifted back to where it should be. The expected focus point (blue line) now coincides with the smoothed actual best-focus green-line peak. If you make a similar plot using a wide-angle lens, the bump in the green line won’t have as steep of a peak in it, since focus changes more gradually. Conclusion Focus calibration can get fairly involved, but it’s not rocket science. It is important, however, to get more sophisticated than just manually inspecting the results of a slanted-ruler target photo to calibrate lenses with high precision. You might also find that your lens will shift focus in temperature extremes. All I can suggest in that case is that you save calibration settings for “cold” and settings for “hot” days. I tape a little piece of paper inside my lens cap with little facts that I’d otherwise forget. In this case, you’d just change the ‘camera’ fine-tune value and leave the ‘lens’ settings alone (on Sigmas or Tamrons). A small focus error gives you a big resolution penalty. Long lenses in particular need to be calibrated incredibly well, or the intended subject (e.g. the near eye) resolution will pay a terrible price. If quality images are important to you, then spending the time to calibrate lenses properly will reward you with significantly better shots.

The Nikon D850 includes a “Focus Shift Shooting” feature for focus-stacking, but it doesn’t give you any guidance on how to stack the shifted photos it captures into a “stacked photo”. This is a nice camera feature, but if you have to use a tripod to take the shots, not many people are ever going to use it. How many photographers have you seen walking around hauling a tripod? What follows is a technique to let you hand-hold your D850 and still accomplish focus-stacking. It involves the use of the free Nikon Capture NX-D and CombineZP programs to make a perfect stacked image. You can also use the CombineZM program (both programs were written by Alan Hadley) using the same procedures as with the CombineZP program. It has fewer stacking macros, but otherwise has about the same abilities as the CombineZP program. I’m running the program(s) under Windows 10. If you’re interested, “combine z” means combine shots in the ‘z’ (vertical) direction, and the ‘p’ is his “pyramid” algorithm for his latest technique to combine the sharp parts of each shot. There are, of course, focus-stacking programs that you can buy (such as Helicon Focus and Photoshop) if you’d rather pay for a stacking program. Personally, I have found that Photoshop fails quite often during the stacking operation, but the CombineZP program succeeds. I haven’t tried Helicon Focus. The D850 can take the shifted photos at a rate of 5 frames per second, so you can get your pictures for stacking at a very quick pace. This pace means that most subjects won’t move very much before you have captured your photos. This also means that most times you don’t even need a tripod to do focus-stacking. It’s not fool-proof, but this procedure will get you better results than you might think. Even if you use a tripod, wind is still the enemy for doing focus stacking with flowers. The alignment capabilities of CombineZP can even help in this case (within reason). This doesn’t mean you can be careless while shooting the pictures; you should always endeavor to hold as still as you can. Since it’s only a few seconds, it shouldn’t be too much of a burden to do this. The free Capture NX-D program is used here to easily convert your raw shots into TIFF format, using its batch-processing feature. The free CombineZP/ZM program performs the photo alignment and focus-stacking operations. D850 Focus shift shooting menu To get your shots, you use the Photo Shooting Menu “Focus shift shooting” option in the Nikon D850. For this article, I used the default “No. of shots: 20”, “Focus Step: 3”, “Interval = 0”, “Exposure smoothing = ON”, and “Silent Photography = OFF”. I used my Sigma 70-200 f/2.8 with Sigma TC-1401 1.4X teleconverter at f/5.6, 280mm, and about 4 feet from the target. These conditions result in a very narrow depth of focus for each shot. I had my camera set to continuous-high speed shooting and aperture-priority. If you want minimal camera vibrations and happen to have a tripod handy, then the “Silent Photography” option is really good. Also, if you’re not looking through the viewfinder while shooting, remember to use the eyepiece shutter to block any light from entering the camera. After I had the desired “Focus shift shooting” camera settings, all I had to do was select “Start” and hit the middle button of the multi-selector to accept the settings. Following a brief message that said “Processing” in the rear camera display screen, the D850 took the 20 shots and stopped automatically. The 20 shots were all captured in 4 seconds, just as advertised. The top LCD screen shows a frame countdown while shooting. I was reasonably careful to not move too much, so that the alignment software used later on would have a better chance of success. Let’s not press our luck. First shot of the stack The shot above is the first exposure in the sequence, showing how only a couple of the succulent leaves are in focus. Yes, I could have stopped down the lens to get more in focus, but there’s no way to get the depth I wanted at any aperture. The stack will rectify this. I reviewed the last shot taken to verify that the focus had shifted sufficiently to capture the depth of focus I was after. It seemed fine, so I didn’t have to repeat the shooting session after changing either the “focus step” size or the number of shots to take. It’s also possible, if the last shot in the sequence hasn’t focused far enough, to just repeat the shooting without changing any settings at all. The camera will pick up where it left off and simply add to the sequence. This assumes the step size of each shot is suitable (there’s focus overlap shot-to-shot) and doesn’t need to be changed. The D850 engineers did their best to figure out what the focus change per-shot should be, even though you can have an extra measure of control with the “focus step width”. If you stop down the lens more, the per-shot focus change will increase; it will decrease if you open up the aperture. They were also smart enough to make the shooting automatically stop if the lens reaches infinity focus, and not just keep shooting the rest of the requested shots stuck on infinity. I put the 20 raw-format shots into a folder on my computer, and then I used the Capture NX-D batch-processing feature to convert the shots into 16-bit TIFF format with LZW compression. I did this step, because the CombineZP program doesn’t know how to use raw-format pictures. Run Capture-NXD to convert Raw into TIFF Tell Capture NX-D to run a batch process Select the desired conversion options in Capture NX-D It’s a bit time-consuming to convert lots of images, but Capture-NX-D will keep you updated with its progress. The top of the program window will show a ‘batch progress’ indicator with a count-down of pictures left to convert. Align and stack the TIFF images using CombineZP The CombineZP startup dialog The CombineZP program startup screen doesn’t have any menu bar. If you want conventional menus, like me, then you should click on the “Enable Menu” icon. The shot above shows the “menu” view enabled. Select the files to process Next, select the “File | *New” option and select the photos in the folder with the TIFF pictures that Capture NX-D just made. File dialog while loading selected TIFF images After all of the files get loaded, the first shot in the set of images will be displayed on the screen. Align pictures from a hand-held focus-shifted collection Since I didn’t use a tripod, I next selected the “Macro | Align and Balance Used Frames (Thorough)” option. This is where the magic happens to fix your unsteady hand. The program then proceeds to analyze, align, and exposure-balance the shots. The photos are shifted/rotated/scaled in order to prepare them for stacking. A message “Finished Executing Align and Balance…” is displayed when this step completes. Be patient. If you happened to have used a tripod for the focus-shift shooting, then you could simply skip the step above and go straight for the “stacking” step that follows. Depending upon your lens, however, you may elect to do this step even when using a tripod (focus-breathing, etc. may happen). Wind happens, too. Do Weighted Average macro selection Next, select the “Macro | Do Weighted Average” option. The program will proceed to focus-stack the aligned images. The “Weighted Average” algorithm is one of a few different ways that focus-stacking can be performed in this program. Did I mention that patience is a virtue? Do Weighted Average macro complete dialog When processing completes, crop the central portion of the finished picture. The stacked image borders have a sort of mirror-image effect, which needs to be cropped from the final picture. Aligned, stacked photo with unwanted edges The shot above shows how much more of the scene is now in focus, but there are stacking artifacts all around the border of the frame. It usually looks like the original image is floating on a pond. Use the left-mouse to draw a rectangle around the portion of the stacked image you want to save. Then, select the “File | Save Rectangle As” option and save the final cropped image into a “jpeg” file with the desired quality. If you want to edit the shot further, you can also save the shot in TIF format or BMP format. The un-cropped stacked shot will be automatically saved in a sub-folder called “Output”. Finished hand-held stack result “Do Weighted Average” Depending upon your image, you might want to try some of the other stacking macros. Some stacked images have a small amount of ghosting, and either a different stacking macro or selecting a subset of the input images may help rid the ghosting. Most artifacts show up on the edges of the frame, so if the main subject fills a little less of the frame, you may have less editing work to do later. Depending upon the subject, the fineness of the focus shift per shot and other factors, different macros will perform better than others. You’re encouraged to try each to see what works best. If you end up with a small amount of edge ghosting, you can use a ‘healing brush’, clone-stamp, etc. to fix up the final image. The worse you are at holding still while shooting hand-held, the better the chance of having some little ghosts haunting your stacked photo. Notice above how much more of the scene is in focus, compared to the shot at the top of this article. What you don’t notice is that the hand-held stack is perfectly aligned; it looks like I must have used a tripod to get that perfect alignment. Tripod-mounted stack For comparison purposes, I’m showing a 20-shot focus stack of the same subject that I did while using a tripod in the photo above. Unless I told you which stack was which, I’ll bet that you couldn’t tell. I was able to skip the “Macro | Align and Balance Used Frames (Thorough)” step, since the tripod retained the shot-to-shot alignment (and I didn't have to contend with wind). It is, of course, helpful when you can use a tripod. Critical framing is much easier, and generally your shots will be a bit sharper. The shot-to-shot focus plane step sizes will be more consistent, too. Conclusion This procedure frees you from having to use a tripod with focus-stacking images. It may not work in all cases, but it’s more robust than you might think. I have tried stacking shots taken both with and without using a tripod several times, and usually I couldn’t tell a difference in the results. If you try shooting highly-magnified photo stacks, then you will unfortunately need to use a tripod. Focus-shift shooting should always be in the back of your thoughts while shooting suitable subjects, if your camera supports it. Since you don’t necessarily need a tripod, why not take the shots just in case? You can also try ‘manual’ focus-shift shooting, if your camera doesn’t support doing it automatically (I have done this for years using a close-up bellows). The same goes for high-speed hand-held exposure bracketing for HDR. Digital shooting is cheap, so take advantage of that fact. Someday, Nikon may just do all of this stacking work in-camera, but I’m not holding my breath. They should also be able to calculate the exact focus-shift values automatically, since the camera already knows the starting distance, aperture, and focal length. Someday.

Nikon tells you this combination won’t work. Sigma tells you this combination won’t work. Let’s see how this stacks up against reality. A big problem in macro photography is “working distance”. Lots of insects are fraidy cats, and simply won’t hang around if you get close. Long macro lenses are quite expensive, and big telephotos don’t focus close enough. What to do? Micro-Nikkor 105mm f/2.8 with Sigma TC-1401 I recently tried the forbidden combination of the 105mm f/2.8 Micro-Nikkor AF-S VR lens with the Sigma TC-1401 1.4X teleconverter. Would it fit? Would I lose autofocus? Would resolution be terrible? Do you get a 40% longer working distance? Does vibration reduction fail? Is cropping a shot better than using a teleconverter? Is camera focus fine-tune available? Does the camera see this combination as 147mm f/4.0 or does it still see 105mm f/2.8? Lots of questions. Lots of testing to be done. Notice in the shot above how small the teleconverter is. You can barely even tell that it’s attached. By the way, attach the teleconverter to the lens before attaching it to the camera. First things first. I checked the clearance between the back of my 105mm lens and the front of the teleconverter. My micrometer said they shouldn’t crash into each other. I couldn’t see any fundamental incompatibilities, so I tried to connect them together. Success. Autofocus Impact I had read about autofocus going crazy when you connect this combination to a camera and turn power on. I attached the pair to my D850 and turned on power. No problem. The internet seems to be wrong about that particular issue. The Nikon D850 is guaranteed to autofocus with lenses as slow as f/8.0. The 105mm, when focused down to 1:1 magnification, has the marked f/2.8 reduced to f/4.8. This means that minimum focus would now get you f/6.7 with a teleconverter (or f/4.0 when focused at infinity). So far, it seems like autofocus could still possibly work. Next, I tried pressing the AF-ON button. Lo and behold, it could focus. I walked into a dim room and tried to focus again; again it succeeded, but it did quite a bit of focus-hunting. Pressing my luck, I also tried the teleconverter on my D610: autofocus still works, but it hunts a bit more on that camera. Even in bright light, phase-detect focus is noticeably slower and the lens makes a sort of clicking sound while focusing on any camera. Focus takes about ½ second, versus near-instant without the teleconverter. Trying Live View contrast-detect autofocus, I found that it behaves flawlessly, just like the lens does without the teleconverter attached. The focus chattering didn’t change with either AF-S or AF-C. It was worst with single-point focus, and chattered the least with group-area focus. I couldn’t find a way to stop the chattering entirely. Contrast-detect definitely works better than phase-detect with this teleconverter. Forget about birds in flight. I don’t think that you’d want to use this combination with regular-distance shooting, such as portraits, while using phase-detect autofocus. For those non-macro scenarios, I’d recommend you simply remove the teleconverter. Everything will work using the teleconverter, but the extra focus hunting and chattering sounds are annoying. Manual Focus Focus peaking with Live View manual focus on Nikon D850 Most people probably switch to manual focus with macro lens close-ups, including me. Autofocus at such short distances can be an exercise in futility with any hand-held macro lens. If you haven’t tried focus-peaking mode in Live View and your camera supports it, you should check it out. Just like with other lenses, you need to switch the lens to “manual” to enable focus-peaking. Outdoors, I often use my LCD viewer/magnifier to get a great screen image while also shielding the screen from bright light. Holding the viewer against both my eye and the camera can be helpful for keeping things more steady, too. Focus-peaking makes critical manual focus quite easy. Mirrorless users are spoiled, getting this feature inside the viewfinder. Vibration Reduction What about using vibration reduction? This 105mm VR should get me about 4 stops of shake reduction, or shots down to about 1/8 second. I set my camera to use manual exposure with auto-ISO, and set 1/8 shutter with and without VR active. Using VR, the shots are sharp; without, they’re total mush. VR works with the teleconverter just fine. Lens Exif Data How about lens information? I tried to set the aperture to f/2.8, which shouldn’t be possible (f/4.0 should be the maximum). Oops. I can set it to f/2.8. The Nikon D610 doesn’t know the teleconverter is attached, and neither does the D850. But I couldn’t help but notice that exposures are perfect, regardless. The photo exif data incorrectly shows “f/2.8”, “105mm” and also notes (correctly) when VR is enabled. Exif distance data with the teleconverter is also incorrect. Focus Fine-Tune What are the implications for focus fine-tune? Since the camera doesn’t know a teleconverter is connected, it means that you’d end up overwriting the fine-tune calibration for the 105mm lens without the teleconverter. Not terrible, but certainly not ideal, either. If you want to use phase-detect autofocus, though, you will almost certainly need to set the focus fine-tune for this combination. Remember to set it back to the old value when you remove the teleconverter… Working Distance What kind of working distance (from the front edge of the lens) do you get at the minimum focus distance? You get 6.0 inches. That’s the same as no teleconverter, but the lens is at what’s now 1.4X magnification instead of 1.0X. For life-size magnification, you can back off to about 8 inches, or 40% further away. D850 Focus Shift Shooting (Focus Stacking) The D850 can help with a major problem in macro photography: depth of focus. The D850 can automatically take shots for focus-stacking. “Focus shift shooting” does work with the teleconverter attached. The lens needs to be kept in auto-focus mode, and the lens needs to be pre-focused onto the target (or a little in front of it). As a test, I chose to NOT use Live-View for these shots. I use aperture-priority mode, and I definitely put the camera onto a tripod for macro shooting. Lens VR is turned off, single-shot mode, and I closed the eyepiece shutter. For the test, I chose 20 shots, with a focus step width of 3, an interval of “0” until the next shot, exposure smoothing ON, Silent photography ON, and hit the multi-selector middle button after selecting “Start”. Because of selecting “silent photography”, the only vibrations during the automatic shooting sequence were due to the automatic focusing steps of the lens (full electric shutter). Nice. Getting further from the subject, thanks to the teleconverter, was quite helpful with lighting in this little test. You can, of course take the series of shots manually in place of using this particular camera feature. The D850 doesn’t actually do any photo stacking, it just makes the shots to stack. I used the free CombineZP to stack the shots, after using Nikon CaptureNX-D to batch-convert the raw shots into tiff format (CombineZP can’t use raw-format shots). I chose to try the “Pyramid Weighted Average” macro to see what it could do. "Macro" here means running a little program to do a task. After that, I tried the “Do Stack” macro. I prefer the “Do Stack” result. There are several macros to choose from. First shot of a stack of 20. Skinny focus. f/8 ‘Pyramid Weighted Average’ macro stack. ‘Do Stack’ macro. Resolution Impact Now, for the biggest question. What happens to resolution? I have read that a Sigma Teleconverter/Nikkor lens combination is very bad for resolution, and the frame edges are horrific. I don’t have any facilities to measure lens resolution in the macro region, so I’m just going to show resolution results at conventional distances (around 5 meters). You’ll have to infer that the teleconverter resolution impact at regular distances is similar to the macro distance impact. If the resolution loss using the teleconverter is less than 40%, then it means that using the teleconverter is better than merely cropping the shot. Since it’s a 1.4X teleconverter, the focal length is increased by 40% from 105mm to 147mm. The following measurements are done using the Nikon D850. As always, my shots are done using un-sharpened raw format. All resolution measurements are in units of MTF50 lp/mm. The resolution plots separate out meridional (tangent) and sagittal (wheel spoke) direction measurements. MTF50 lp/mm with teleconverter, 147mm f/4.0 The 105mm lens was set to the marked f/2.8 aperture. The ‘exif’ data should have noted a focal length of 147mm and f/4.0. Peak resolution is about 41 lp/mm. Notice that the edges of the full-frame aren’t degraded, compared to the lens center, even wide-open. Already, the resolution is fine (I measure ‘fine’ as being above 30 lp/mm). MTF50 lp/mm, no teleconverter, 105mm f/2.8 The wide-open resolution plot for the 105mm without a teleconverter is shown above. Peak resolution is about 53 lp/mm at f/2.8. The resolution loss when attaching the teleconverter is 41/53 = 0.77, or a 23% drop at f/2.8. MTF contrast plot, wide open with teleconverter The plot above is the traditional wide-open MTF contrast plot, using the teleconverter. This is 147mm, f/4.0. MTF contrast plot, 105mm f/2.8 , no teleconverter The plot above is the traditional wide-open MTF contrast plot, without the teleconverter. This is 105mm, f/2.8. Overall contrast is nearly 10% higher than with the teleconverter attached. MTF50 lp/mm with teleconverter, 147mm f/5.6 MTF50 lp/mm, no teleconverter, 105mm f/4.0 Attaching the teleconverter at f/4.0 (now 147mm f/5.6) drops the resolution by 49/57 = 0.86, or a loss of 14%. MTF50 lp/mm with teleconverter, 147mm f/8.0 Nice and sharp at this aperture, with better depth of focus. MTF50 lp/mm, no teleconverter, 105mm f/5.6 Attaching the teleconverter at f/5.6 (now 147mm f/8.0) drops the resolution by 51/62 = 0.82, or a loss of 18%. MTF50 lp/mm with teleconverter, 147mm f/11.0 Diffraction is starting to set in and messing with resolution. MTF50 lp/mm, no teleconverter, 105mm f/8.0 Attaching the teleconverter at f/8.0 (now 147mm f/11.0) drops the resolution by 49/61 = 0.8, or a loss of 20%. MTF50 lp/mm with teleconverter, 147mm f/16.0 Please ignore the left-side dimple in the meridional-direction plot above. I didn’t realize a shadow had been cast onto the edge of the target, which affected the left edge measurements. Resolution is still okay, but diffraction is getting much heavier. MTF50 lp/mm, no teleconverter, 105mm f/11.0 Attaching the teleconverter at f/11.0 (now 147mm f/16.0) drops the resolution by 42/53 = 0.79, or a loss of 21%. MTF50 lp/mm with teleconverter, 147mm f/22.0 Please ignore the left-side dimple in the meridional-direction plot above. I didn’t realize a shadow had been cast onto the edge of the target, which affected the left edge measurements. MTF50 lp/mm, no teleconverter, 105mm f/16.0 Attaching the teleconverter at f/16.0 (now 147mm f/22.0) drops the resolution by 29/41 = 0.71, or a loss of 29%. The teleconverter at this aperture (f/22) is getting into heavy diffraction, so the resolution loss gets much worse. I consider this aperture to be unacceptable for teleconverter use. In summary, the resolution drop by attaching the teleconverter is typically about 20%. Since the focal length was increased by 40%, this is definitely superior to merely cropping the picture to get the same field of view. Frame edges are quite good, thus disproving lots of the internet hearsay about the resolution disaster. Your shots can be tack sharp with or without the teleconverter. Your camera support, accurate focus, and lighting will impact getting sharp photos at least as much as the raw lens/teleconverter resolution. You also probably want to look into focus stacking, since depth of focus is one of the biggest issues in macro photography. Conclusion Here’s an “impossible” combination that does the impossible. Aside from stressing the phase-detect autofocus system a bit, you probably won’t even notice if the teleconverter is attached or not. If you’re willing to stick with either contrast-detect focus or manual focus, you’ll be very happy with the shots from this combination. If you’re hooked on phase-detect focus at all times, then you won’t be happy with this combo. But you won’t be complaining about sharpness. I’m glad I finally got around to testing this setup. I had fallen into the trap of believing what I read on the internet. I intend to use the Sigma TC-1401 and Micro Nikkor 105mm f/2.8 team quite often in the future; it may help a bit with those shy bugs. Lighting is simpler at these longer distances, too. Sample Photos Coin at 1.4X magnification. D850 147mm f/14.0 1/30s Even at f/14.0, the shot above strains to have enough depth of focus at the minimum focus distance. It’s pleading with me to use focus stacking. Nonetheless, it looks pretty sharp to my eye. The coin is 6 inches from the front of the lens. I used Live View contrast-detect focus here, to prove it works, but normally I’d be using manual focus with focus-peaking. Coin at 1.0X magnification. D850 147mm f/16.0 1/20s At 1.0X magnification, you get about 8 inches working distance from the front of the lens. Compared to this, the US $1,400.00 Canon 180mm f/3.5L USM lens gets you about 9.5 inches working distance; not that much different. I used Live View contrast-detect autofocus for this shot, too. Fairy Duster, D850 147mm f/4.0 (wide open) 1/500s Aside from having almost no depth of focus at this distance, the 105mm wide open with the teleconverter up close is quite nice. I even used phase-detect focus here, just to see if it would work properly.

You probably think that it’s a done deal after you get your lens focus calibrated for your camera. Maybe, maybe not. Depending on things like how long you’ve had that lens or how many bumps have accumulated in your travels, your lens may have changed a little bit. Little changes can have a bigger impact than you might expect, however. My middle-aged Sigma 150-600 lens I have had my Sigma 150-600 lens for over 5 years now, and I started having suspicions that some of my shots were consistently just a little bit off from nailing focus. Unsurprisingly, the most focus misses were at 600mm, while shorter focal lengths still seemed calibrated. The same focus misses would happen on more than one camera body, so I knew it was the lens. I noticed that the infinity focus calibration still seemed correct, but shots in the 30-to-60 foot range were off by about an inch or two when zoomed out beyond 400mm. Since this is a Sigma lens, I have the option to calibrate focus for 150mm, 250mm, 400mm, and 600mm. I can also calibrate at 9.2 feet, 20 feet, 48 feet, and infinity for each of those four zoom settings. The focus target (from the MTFMapper site) I use a focus target that is comprised of many little trapezoids with a big trapezoid in the middle. When the left side of this target is rotated away from the camera, the trapezoids give the illusion of being rectangles. The big middle rectangle gives your camera an easy target to guarantee focus on a known edge. I set up my focus chart at 48 feet (14.6m) and shot it at 600mm. I use the MTFMapper program to analyze the chart shots, so that I get very precise answers about what’s in focus and what’s not. This particular distance and focal length wasn’t arbitrary; it’s one of the 16 Sigma fine-tune settings in their Optimization Pro program for this lens. I found out that yes, indeed the focus calibration was off. Not by a huge amount, but it was generally focusing too far by about an inch (25mm). By the way, the MTFMapper site offers multiple focus-chart files with different amounts of perspective distortion to use with different lens focal lengths, such as wide-angle lenses. So, am I just way too picky? The focus error resulted in a loss of resolution of several lp/mm. If your own lenses could get improved resolution, wouldn’t you jump at that chance? I think it’s well worth the effort to do this recalibration. Focus target detail with MTF50 edge measurements The (cropped) shot above shows the center of my focus chart, shot at 600mm from 48 feet away. The numbers on the little black trapezoids are resolution measurements in units of MTF50 lp/mm. I always shoot in ‘raw’ format; measurements using jpeg files are vastly different. The left side of this chart is farther from the camera than the right side (it’s rotated by 45 degrees). I used phase-detect focus and aimed my focus sensor at the right-hand side of the large black rectangle (where it’s showing the yellow measurement of “43.8”). The highest resolution edges are generally about 3 “little” rectangles to the left of the big rectangle right edge. This focus error is only about an inch along the lens axis. In this shot, the measurements that are displayed in yellow indicate that those edges are perfectly vertical or horizontal, versus the cyan-color measurements on edges having a slight slant to them. Don’t put a lot of stock in the MTF numbers in this shot, since this isn’t a proper resolution-measuring plot, the target is only a small part of the image frame, and the target (on purpose) isn’t parallel to the image sensor. It’s fair to compare these numbers to other shots taken in the same shooting conditions, however. I have larger focus targets than the one shown above, but focus targets with smaller rectangles (trapezoids, actually) give me a better idea of exactly where the best focus is located. The measurements show that best focus is further away from the vertical edge I aimed at, and I need to use a “-” focus calibration shift to get the lens to focus closer to the camera. The “large” rectangle is only 2 inches (50mm) tall, and I remind you that I’m shooting this from 48 feet away! Profile plot of target from MTFMapper The profile plot shown above makes it easier to see where the focus lands (at the green line peak). The blue line indicates where the right-hand side of the target rectangle edge is (where I pointed the camera focus point). Clearly, the lens is back-focusing. The little red dots represent each measured tiny rectangle edge resolution, and the green line is a smoothed plot of these measurement averages. Note in the plot above that the intersection of the blue line and the green line has a resolution around 44, versus the green line peak of around 54, showing resolution loss of about 10 lp/mm at the desired focus plane. As I mentioned, these resolution numbers aren’t strictly reliable for this style of chart, but they’re at least representative of the loss in resolution. Who could have imagined that a focus miss of about an inch would result in such a big resolution loss on the intended target? This is typical long-lens behavior, however (don’t miss focusing on that animal’s nearest eye, or you can really tell). It’s worth noting that some lenses (usually the super-fast lenses) can also shift focus with an aperture change. On these lenses, you need to set the desired aperture for calibration. On most lenses, you just need to set the widest aperture for testing. I know from experience with my Sigma lens calibration using their USB dock and their “Sigma Optimization Pro” program that I need a calibration change of about 2 units. I saw that I had previously saved a calibration setting at 600mm and 48 feet of “-4”. I reprogrammed the calibration fine-tune value to be “-6” instead, to pull focus a little closer to the camera by about an inch at 48 feet. The Sigma lens focus-fine-tune firmware is smart enough to interpolate all of the in-between calibration settings for the lens focal length and the focus distance. The 500mm calibration would be affected by both the 400mm and 600mm calibration values. While I had everything set up, I also took shots at the 400mm zoom setting. At the 48-foot distance, it seemed to focus accurately. I set up the target at 20 feet from my camera and repeated the tests at both 600mm and 400mm. At this distance, the 600mm setting focused perfectly, but the 400mm setting focused a little too close. I changed the 400mm calibration at 20 feet from “-10” to “-9”, to make it focus a little farther away. I didn’t see any calibration shifts at shorter focal lengths, so I left those values alone. Sigma Optimization Pro calibration settings As seen above, I now have an updated focus calibration for the 600mm setting at 48 feet (-6) and a new setting for the 400mm setting at 20 feet (-9). These two tweaks got my Sigma perfectly focus-calibrated again at all focal lengths and distances. I sound like a broken record, but I wish all lens makers had this multiple-calibration feature. It makes all the difference in how a lens performs. It’s so elegant that you’d think all lens makers would adopt this scheme, but so far only Tamron has followed Sigma’s lead. Improved focus accuracy with new fine-tune calibration The shot above shows an analysis of the focus target using the new calibration settings. The focus (and highest resolution measurements) is shifted back to the correct distance. You always need to take several shots and re-focus between each shot. There is a small shot-to-shot variation, and you need to determine where the “typical” focus lands. Profile plot with new fine-tune calibration You can see in the plot above how focus has shifted back to where it should be. The expected focus point (in blue) now coincides with the smoothed actual best-focus green-line peak. Conclusion The focus change isn’t huge, but I’m now getting measurably improved sharpness where I aim my camera’s focus point. There’s an overall improvement of about 20 percent in resolution where I pointed the focus sensor when shooting at 600mm. A small focus error gives you a big resolution penalty. Long lenses need to be calibrated incredibly well, or the resolution will pay a terrible price. I think it’s unreasonable to expect that your gear doesn’t change a little bit with age (and abuse). It’s slightly irritating to go through this exercise more than once, but I’m glad that I did. I have to chide myself periodically to not get lazy. Everybody ends up losing a step or two with age, and camera gear is no different. I’d recommend you take a second look at your own cameras and lenses just to verify that everything is operating at optimal efficiency. Also, do your testing at the same kind of temperatures that you photograph at, since thermal changes can also throw off focus. This particular lens is made out of “thermally stable composite” to minimize focus changes with temperature. I’m keeping an eye on any more changes in this lens, but I haven’t noticed any more calibration shifting yet. There’s no way of knowing why the calibration shifted, but the important thing is to note that it hasn’t shifted any more since I did these tests. If I were to find yet more focus shifting, then it would probably mean that this lens has reached retirement age. As an aside, I also pointed a flashlight into the front of this lens, and it still shows NO visible dust has gotten sucked into it after over 5 years of pretty heavy use! Sigma really did a great job of sealing this lens. I’d still recommend that you stay away from those “colored-dust-throwing” festivals, however. Let’s not press our luck. As an additional aside, I’d again like to thank Frans van den Bergh for providing his excellent MTFMapper software and test chart files. His program can help you take your camera gear to the next level.

Why do photographers lug around big telephotos? Wouldn’t it be much better to have a really sharp shorter lens and be able to crop the shot? In a word, “no”. Nikon D610 550mm f/7.1 from 17 feet away The shot above, taken with the Sigma 150-600 Contemporary at 550mm, was at a distance of about 17 feet (5 meters). The depth of focus is 0.11 feet, or just 33 millimeters. The aperture was f/7.1 to try to get the whole bird’s head in focus, but no more. The distracting bushes behind the bird would have ruined the shot if they were in focus. The bird was nervous enough at 17 feet; it would have simply flown away if I had approached any closer. Yes, I did try getting closer, and yes, it did fly away. No matter how sharp your lens is, and no matter how much resolution your camera sensor has, you can’t get the “look” that a long focal length provides merely by cropping your shorter-focal-length-lens shots. Even if you could buy something like a fast 200mm f/1.0 lens (which doesn’t exist), you still couldn’t get the look that a “slow” 600mm telephoto gives you at long distances. The narrow depth of focus that a long lens gives you cannot be replicated by shorter lenses, no matter how large the aperture that shorter lens has. This last statement implies that you take your shots from the same distance for each lens being compared. Here’s an example: I have a 600mm f/6.3 lens, and I shoot a subject from 50 feet away. The depth of focus is just 0.77 feet, or about 9 inches. You might not think that such a slow lens could manage such a narrow focus depth, but that’s the reality. A 200mm f/2.0 lens is the fastest existing telephoto of that length that I’m aware of (and almost $6,000.00). What’s the depth of field for that lens at 50 feet? It’s 3.82 feet, or 5 times as large as that slow 600mm f/6.3 lens! By the way, this 200mm lens weighs 6.5 pounds, or almost 50% more than the 4.5 pound Sigma 150-600 Contemporary. Now, let’s imagine we have that mythical 200mm f/1.0 lens and shoot at the same 50-foot distance, wide-open. Let’s even imagine that our lens is infinitely sharp, and our camera sensor has infinite resolution, so that we can crop any amount we want. How narrow is that depth of focus? It’s going to be 1.13 feet, or nearly twice as much! And I can only imagine what that f/1.0 lens might weigh. So why do I even care how much the depth of field is? I care because of the “look”. Subject isolation with telephotos and their creamy, de-focused backgrounds are what it’s all about. Nothing screams ‘amateur’ like photos that have busy, distracting in-focus backgrounds with fences or telephone poles. This desirable telephoto narrow-focus effect is quite the opposite of what you want with nearly all super-wide-angle lens photos, where you’re after near-to-far being sharp. But that’s another story. It’s no fun hauling around big glass all day, but there’s a real reason that people do it. It’s to get “the look”.

This review will concentrate on the lens MTF50 resolution performance and how well the lens auto-focuses. Repeating the Nikon specifications of the lens isn’t why you should be reading this, since that data is readily available in any number of other places. This lens is often referred to as the "wedding photographer's lens". On FX, it gets you 95% of the focal lengths you'd need at a typical wedding, in addition to the wide-enough aperture for dim venues and great bokeh. Personally, I'd pair this baby with the Nikkor 85mm f/1.4 and you're good to go. The usual disclaimer: this is looking at a single copy of the lens. Yours will be different, but hopefully ‘similar’. These tests were done using a Nikon D610 (24 MP, 5.95 micron pixel) with un-sharpened 14-bit compressed RAW format. Nikkor 24-70 f/2.8 VR with lens hood. Massive. Here is a link to get pretty good overall information on this lens. They reduce resolution measurement down to a single number for an f/stop setting. It’s not that simple; resolution is a 2-dimensional thing, and there are sagittal and meridional characteristics within those two dimensions. Calibration First things first: focus calibration. My lens copy needs a fine-tune adjustment of about +16 on my camera, which is vaguely alarming for such a high-cost “pro” lens. I say “about +16”, because this lens needs a different focus calibration setting at different focal lengths. I am using the MTF Mapper software to get focus calibration measurements and MTF50 measurements, which I explain at this link You should really be using tools that give you answers “by the numbers” to get the most out of your equipment. The focus target I use is an A0-sized print, oriented 45 degrees to the camera sensor plane. Since the camera focuses on the vertical edge of a giant trapezoid, there’s no ambiguity about where the camera is focused. See the picture of the target below (the trapezoid looks more like a rectangle, due to the perspective distortion). I use “AF-C” with a back-button focus for this test, since that’s exactly the way I shoot the camera. Too bad Nikon focus calibration is so primitive, compared to Sigma. This lens (read ‘most lenses’) desperately needs calibration for different focal lengths and distances. Oh, well. I had to split the difference for the fine-tune value, giving more bias to 70mm (since focus errors are more noticeable there). For a typical factory-calibrated lens, my D610 needs a fine-tune value of +6, so measuring a +16 (or a little higher) doesn’t inspire confidence in Nikon quality control. As long as it stays within +- 20, I suppose I shouldn’t care. In case it’s not obvious, you never use “Live View” for focus calibration tests. Only use “phase detect” focus. I always use “AF-C” and not “AF-S”, since that’s exactly how I always shoot (in addition to back-button focus). Fine-tune +16 not quite enough at 70mm. The peak should align with the blue line. Fine-tune +16 a little too much at 24mm. The blue line is where the focus sensor was placed on the target; the green peak is where actual focus was located. What the focus target looks like at 70mm. It’s rotated 45 degrees to the camera. The left side is farther from the camera than the right side. I taped it on top of my resolution target, which is why you see faint gray squares (it doesn’t affect the calibration). Focus Speed and Repeatability This lens focuses (phase detect) very quickly and was totally repeatable (in decent light), so no complaints there. By the way, you should always conduct focus tests in good light, or else you’re wasting your time with trying to calibrate against a moving target. EV 10 or brighter is a good light level to use while testing. Even in dim lighting, I didn’t experience any focus hunting. Vibration Reduction (VR) This lens has state of the art VR, which is one of the biggest upgrades over the previous version of the 24-70 lens. I got nearly 4 stops improvement. I’m guessing that this is the main reason somebody would opt for this lens versus getting the previous version. ‘E’ Electronic Aperture Maybe you have the D5 and are shooting at 12 fps. Maybe you can tell the difference in the electronic aperture versus the mechanical aperture. I honestly can’t tell the difference in shooting with a mechanical or electronic aperture. Infrared For those of you interested in shooting infrared, this lens produces a minor hotspot in the middle of the field of view. If you stick to f/5.6 or wider, the hotspot virtually disappears. Since I usually shoot at 24mm and f/8 with infrared, I use Lightroom with its "radial filter" to decrease the exposure in the middle of the shot by a little more than a third of a stop to fix the hotspot. I also have to shift focus to about 8 feet to get infinity in focus with my 850nm infrared filter (again at 24mm). Centering Test Centering: out-of-focus rings should look perfectly symmetric The out-of-focus rings look perfectly symmetric about the center, indicating that the optics are well centered. This also gives you some idea about the bokeh, which I consider to be excellent. Resolution Here’s the meat of this review. Although the data below is in terms of “MTF50 resolution”, keep in mind that camera sensors with larger pixels will actually produce worse results in terms of “MTF50 lp/mm” values for a lens. You need to combine the MTF50 values with the size of the camera sensor to arrive at the overall picture resolution, typically expressed in “line pairs per picture height” (LP/PH). It’s simple to convert, however: LP/PH = MTF50 * SensorHeight_mm. The D610 sensor height is 24mm, so lp/ph is just (MTF50 * 24.0). For instance, a lens that has an MTF50 lp/mm of 40 gets (40*24) or 960 lp/ph. Like I said, simple. I use an “A0”-sized resolution target, where all of the small squares have a little slant to them. The MTF Mapper software I use gets answers that are very similar to Imatest. The main difference is that MTF Mapper is designed to provide answers separated into “meridional” and “sagittal” directions, just like the MTF line charts that manufacturers distribute. As a side note, however, manufacturers only give you "theoretical" and not actual MTF curves. Since the software can produce full 2-dimensional results, you actually see how the whole sensor performs. I imagine you expect your camera to produce 2-dimensional photographic results, so why wouldn’t you want measurements done the same way? What the resolution target looks like. Mine is mounted ‘upside down’. Very good center results wide open at 24mm. Corners aren’t too bad, either. Note that the meridional and sagittal measurements aren’t that different, so that means that astigmatism is well-controlled, too. Sagittal-direction corners at this aperture are among the best I have seen; meridional-direction corners aren’t so hot. Center MTF50 lp/mm is 45, so this means 1080 lp/ph. Note poor meridional (tangential) and good sagittal corner resolution at f/2.8 Resolution Summary Stop down to get the sharpest corners; otherwise, just set the aperture to get the desired depth of field. Center performance is stellar, unless you go beyond f/11. It’s slightly less sharp at 70mm, but not enough to really notice. I have read complaints about this lens for sharpness, but my copy was able to get 1200 lp/ph (MTF50 = 50 lp/mm) in the center at just about every focal length. I got at least 720 lp/ph (MTF50 = 30 lp/mm) in the corners at all focal lengths for meridional (tangential), except around 35mm, where it topped out at 600 lp/ph. For sagittal direction, the corners were nearly as sharp as the center, which is just brilliant. The real key to getting sharp pictures is focus calibration. I’m astonished at how many people ignore this fact. It’s a pain to do the calibration, but you’re rewarded every time you take a shot after that. Don’t get lazy. I’ll continue to harp at Nikon about being so primitive with their focus fine-tune abilities. So is just about everybody else, except Sigma. Mirror-less manufacturers claim their on-sensor phase-detect solves this, but the focus speed just isn’t there (yet). Sample Pictures #review

The Good I do love my camera battery grips. I have a grip on nearly all of my cameras. My hands are just too big for all Nikons except the D3/D4/D5/D6 series (with their built-in vertical grips). I detest having my pinky finger dangling off of the bottom of the camera; grips fix this ergonomic issue perfectly. I don’t normally do much vertical shooting (computer screens being horizontal and all), but the battery grips make this a pleasant experience when I do. Many of my overlapped vertical shots get combined into panoramas; vertical grips make shooting these a pleasure. It’s comforting to have the extra battery in the grip, but DSLRs are so power-efficient that running out of battery juice is rarely a problem for me. Videographers will of course disagree with this observation. All of the Vello grips come with an extra battery drawer that holds AA batteries, in case you’re somewhere that you can’t recharge your regular camera batteries. Many people don’t know this, but the buttons and controls in a grip still work even if there’s no battery installed inside the grip. Similarly, your camera will work just fine if there’s no battery in the camera, but just in the grip instead. Also, it’s easier to remove the battery from the grip than the camera for recharging. I really love the improved balance and extra inertia that grips provide. Hand-held shots are almost always a tiny bit sharper when using a grip, at least at slow shutter speeds. A typical grip weighs about 8 ounces. Vello makes grips for multiple camera manufacturers, but my own experiences are strictly with Nikons. If you have ever priced the Nikon grips, they’re quite expensive. A couple examples follow. The D500 MB-D17 grip is $370.00 and the D850 MB-D18 grip is $400.00. The D500 Vello BG-N17 grip is just $70.00, and the D850 Vello BG-N19 grip is only $80.00. The Nikon grips typically cost about 5 times as much as the Vello grips! If a Vello grip fails, you can re-buy it many times and still come out money ahead. Vello BG-N19 on Nikon D850 The Vello grip for my Nikon D850 is shown above. It has the exact same finish as the D850. It has a programmable function button near its shutter release. It also has the little joystick like the D850 body has, located near the grip’s “AF-ON” button. It has the front and rear command dials, just like the camera body. This grip feels like an integral part of the camera, and not an add-on. The controls on the Vello grip are programmable, just like the official Nikon battery grip controls. These controls are well-placed and work perfectly. There’s also a newer BG-N19-2 grip that can hold the EN-EL18b (or generic equivalent) to bump up the D850 frame rate to 9fps. You also need a BL-5 cover for this feature. Going the generic route, you can get 9fps for less than $300.00, compared to nearly $1,000.00 to get there using the official Nikon parts. The Vello grips for my D610, D500, and D850 have all worked perfectly for years. The Bad So, do Vello grips have any issues? I’d estimate the risk of an eventual problem at about 40%, purely based on my own experiences. I have had two issues out of my five Vello grips. These issues both involved battery power; in one case, the grip control functionality was also affected. A fairly common problem that I have read about and personally experienced is with the battery drawer. The power to the camera from the grip fails, and the grip’s battery drawer needs to be opened and re-closed to fix it. My D7100 grip (Vello BG-N11) has this problem once in a great while, and it takes about 2 seconds to fix it. This problem hasn’t affected using the grip control buttons or dials, so it’s more of an occasional nuisance than anything else. Vello BG-N4 on Nikon D7000 The Ugly My D7000 and the BG-N4 is shown above. Several times, a loose electrical connection to the camera caused lost battery power from the grip. This problem is quite irritating, and one of these days I should probably just replace this grip. My D7000 grip (BG-N4) camera electrical connector is a little loose, which can cause battery power to be lost. Worse still, the grip’s button controls stopped working. I made the connection more reliable by slightly raising the connector, but the problem still shows up once in a while. Interestingly, the problem never happened in the middle of shooting, but instead only after the camera sits around for several weeks. Other photographers have noted similar electrical connector issues to this, which has, for instance, caused people to lose the 9 fps ability on the D850 (it still would shoot at 7 fps). I decided to see if I could remedy the situation, and get a more reliable connection by raising the connector. Alas, it still isn’t totally reliable after my “fix”. BG-N4 Top plate with arrows showing screws to remove There are 6 ‘Allen’ screws holding the top plate onto the grip (see the green arrows). The right-hand side of the grip shows the “too short” electrical connector and also the storage bay with the camera’s rubber connector cover. My attempted fix involves removing this grip cover, by removing the 6 screws. The cover just lifts off, to expose the electronics. Connector close-up Connector with top plate removed In the shot above, you can see the electronics around the connector. This connector is slightly loose, probably so that it can slip into the camera electrical socket more easily. You can see the grip tripod screw on the left-hand side of the shot. This shot shows two clear plastic shims already in place under the connector base I have added, although they’re hard to see. You’ll note that the Vello grip doesn’t have any weather-proofing seals. It won’t thank you for going out in the rain. Clear plastic shims under connector lip The shot above shows two thin (0.007 inches thick) plastic strips (shims) that I slid underneath the lip of the rectangular connector that has rounded corners. I put a dab of glue on the ends of the shims to keep them in place. The shims slightly raise the electrical connector, so it slips further into the camera body’s electrical socket for a more secure connection. The connector can’t be safely raised much more than what I did. This is a very minor change to the physical connection; I wanted to be able to remove the shims later, in case it didn’t help the situation any. The top plate of the grip cannot be replaced properly if the shims were to raise this connector too much. The grip battery power to the camera is now slightly more reliable, but sometimes it still fails. When I see a power failure, I can (so far) fix it by disconnecting/re-connecting the grip to the camera. I figured that this was a low-risk fix, since the grip is pretty inexpensive. It was also fun to see the electrical workings inside of the grip. Conclusion All in all, I’m happy with the Vello grips. Except for the occasional D7000 startup failures with the BG-N4, I haven’t had any other significant issues in my ten years of using them. I have lost the grip battery power from the D7100’s BG-N11 maybe a dozen times, but as I said I could fix it in just a couple of seconds. I own a total of 5 Vello grips. The good outweighs the bad and the ugly by a large margin. If you have any problems with the Vello grips, you could just re-purchase two or three or four of them and still save money, compared to buying the official Nikon grips. Just don’t go out in the rain with them.