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.

This article details how easy it is to make quality HDR photos using multiple raw shots, Lightroom, and HDR Efex Pro2. Most Nikon DSLRs allow for high-speed, single-shutter-press bracketing. Exposure bracketing, versus single-shot HDR, will greatly expand the range of light that you can record. Capture a range of light that your own eyes cannot match I have verified the following procedures on a Nikon D850, D500, D7100, and D610. Chances are that these shooting procedures will work on all of the Nikon enthusiast and pro DSLRs. A single raw photo can cover at most about 12 stops of exposure range. Theoretically, a 14-bit raw shot can record 14 stops, but today's physical sensors max out at about 12 stops. When you want to go way beyond this restriction, you need multiple shots at different exposures. The last thing you want to have to fuss with is pressing the shutter button over and over to get all of the necessary shots. These cameras let you get the job done with a single shutter button press using the ‘bracket’ feature. Capture the set of pictures to combine In order to minimize any subject movement between frames, set the camera on high-speed continuous shooting. Choose Aperture mode, so that the camera will vary the shutter speed between frames. Set your image capture mode to “raw” (or NEF). Shooting in jpeg format completely defeats the whole concept of capturing a high dynamic range of light. Set a low ISO value, which will maximize the range of light a single shot can capture. If image motion is a problem, then you’ll need to take more photos at a higher ISO, to help freeze image motion in each frame. The extra photos will compensate for the smaller dynamic range in each shot at the higher ISO. Press the Bracket button and rotate the rear (main) mode dial to select the number of shots, such as “9F” for 9 frames. Lesser camera models will have fewer options for the number of frames you can bracket. While still holding the bracket button, rotate the front (sub command) dial and select the exposure value change between shots, such as 1.0 EV. Note that you can’t have the large number of frames in the bracket sequence if you choose too high of an EV change per shot, so stick to less than 2 EV for 7 or 9 shots. Set your camera to “Continuous High” shooting, to minimize how long it takes to capture the sequence of shots. Now, just press and hold down the shutter button to quickly take the whole range of bracketed shots. Your camera will automatically stop after the sequence is finished. If you’re worried about too much subject movement, then take the shots while the camera is mounted on a tripod. You’ll probably be surprised, however, how well both Lightroom and HDR EFEX Pro 2 can hide slight image mis-alignment between each shot. Remember after you’re all done to change the number of bracket shots back to zero frames (“0F”) to turn off bracketing (via the rear dial and the bracket button). I have forgotten to do this many times, to my chagrin. How to process the shots entirely inside Lightroom This procedure shows you how to easily combine your exposure-bracketed shots into a “realistic” HDR rendition. Many photographers actually take offense at the “HDR Look”; I’m not one of those. If your goal is to simply capture a larger range of light similar to what your eyes perceive of the scene, then this procedure is for you. I’m using Lightroom 6, but other versions should have similar procedures. In the Lightroom Library module, import your shots. Mouse-click the first shot in the series you want process. Hold down the ‘shift’ key and click on the last shot in the series. Select the “Photo | Photo Merge | HDR…” menu options. Select the desired merge options. You’ll probably want “Auto Align” and “Deghost Medium”. Click the “Merge” button. Wait… then wait some more. Library module series selection for HDR Lightroom HDR import options Lightroom Merge Preview dialog After the shots are combined, you’ll have a DNG-format HDR photo that you can edit in the Lightroom “Develop” module in the usual way. After you’re happy with it, then export the results to a format like ‘jpeg’. Finished HDR picture done entirely inside Lightroom Night photos are especially suitable for HDR processing. You can transform scenes that would be completely drab during the day into something visually exciting at night. How to process the shots with Lightroom and HDR Efex Pro2 If you like more drama in your HDR shots, then you’ll probably love combining Lightroom with HDR Efex Pro2. Although you can always just process a single shot in HDR Efex Pro2, you will have even more flexibility and light range by processing an exposure-bracketed series of shots instead. Import the series of shots into Lightroom via “Library” module Go to the “Develop” module Mouse-click on the filmstrip first shot in the series Hold down the shift key, and click the last shot in the series Select File | Export… | HDR Efex Pro 2 Choose your desired options for your (Tiff format) shot Finally, click the “Export” button. Select your shots in the ‘Develop’ module to export The screen capture above shows the ‘filmstrip’ selection of 5 shots to export to HDR Efex Pro 2. The shots here are bracketed by 2 stops each. This could mean a dynamic range of up to 20 stops. Export your shots to HDR Efex Pro 2 After HDR Efex Pro 2 launches, you’ll get a dialog of import options, as shown below. HDR Efex Pro 2 import options Just like the Lightroom import options, you’ll probably want to select “Alignment” and “Ghost Reduction”. When you’ve selected your desired options, click “CREATE HDR” to get the combined shot into HDR Efex Pro 2 for the usual HDR editing options. Then have patience, Grasshopper, for the HDR combining to happen. Finished shot from HDR Efex Pro 2 Multiple shots don’t always work You’ll find that some subjects don’t work well with a series of shots. Examples that come to mind are ocean waves and campfires. But guess what? You can always just select a single shot from your series to process as HDR instead. Having extra shots doesn’t mean you’re committed to use all of them. Single shot HDR can look better than you might think. Summary It’s easier than most people think to quickly capture sequences of bracketed shots for HDR processing. You rarely need a tripod, and it only takes a single shutter button press to get the whole sequence. If you take a wider exposure range or more shots than you need, you can always delete the extras later. You will mainly pay a price in longer processing time; if you take fewer shots with a larger EV bracket value per shot, your HDR processing time will be drastically reduced. The quality you get from these bracketing/HDR techniques, especially in landscape shots, is well worth the modest extra effort. This is how you can go well beyond what your own eyes are capable of seeing.

Most camera manufacturers, with the notable exceptions of Sigma and now Tamron, only let you assign a single focus fine-tune calibration setting. Canon will let you calibrate zooms at two different focal lengths, which is slightly better than Nikon. What happens if you have a zoom lens that needs different focus calibration at various focal lengths or different distances? What happens is that you lose resolution on your intended focus target. You would assume that this discussion doesn’t apply to mirror-less cameras or when you shoot using Live View. In those cases, the camera uses the image sensor to detect best focus, and focus calibration doesn’t apply, or does it? Did you know that the Nikon Z mirror-less cameras actually still have a focus fine-tune option in their ‘Setup’ menu? Why in the world would they still offer it? The phase-detect pixels in the image sensor can still lead to focus errors when telling the lens how far to move focus, hence fine-tune is still there. Only the “Pinpoint” focus mode on the Z cameras uses contrast detect, which is, again, really slow. Sorry to burst your bubble. Nikkor 24-70 f/2.8 AF-S E ED VR has terrible focus shift I decided to use my Nikkor 24-70 f/2.8 AF-S zoom for some testing. This isn’t a cheap lens by any stretch of the imagination. It experiences a significant focus calibration shift when zooming it, but you can only calibrate it with a single “fine-tune” value. I’m using the MTFMapper program from here to analyze some shots of a special focus target. First, I want to see how far focus calibration shifts after zooming, and secondly I want find out how much this focus error impacts the shot resolution on the target. In my testing, I’m using phase-detect focus on my Nikon D610. I’m shooting unsharpened raw pictures on a sturdy tripod, and I have turned off vibration reduction. I triggered the shots using an infrared remote, and the mirror is flipped up for at least 3 seconds before tripping the shutter. I take at least 10 shots at each zoom setting, to ensure I know what the “typical” focus distance is. There’s always some natural focus variation between shots, so it’s important to characterize what the range of focus distances actually is. The focus target The MTFMapper program uses a target like the one shown above to analyze focus. The red rectangle shown represents where you should point your camera focus sensor. The target itself is rotated at 45 degrees relative to the camera sensor, with the trailing (outer) edge of the big target rectangle rotated away from you. The trailing vertical edge of the big target rectangle is taller than its leading edge, so that the final photo makes it look more like a real rectangle instead of a trapezoid. This special target shape is intended to fix perspective distortion. The Test I shot the 24-70 lens at 70mm f/2.8 to verify correct camera focus calibration. I just so happens that 70mm on my D610 uses a focus fine-tune value of 0; it’s a non-zero value on my other cameras. The big rectangle vertical edge (underneath the red focus sensor shown above) should be in perfect focus. I took ten shots, where I manually de-focused the lens between shots, and then pressed my focus button to re-focus the target edge with phase-detect focus. I positioned the camera to have the test target just fill the frame. After I verified correct focus calibration using the MTFMapper program to analyze my shots (at 70mm), I then zoomed out to 24mm and moved the camera/tripod until the test target again filled the frame. I didn’t alter the focus fine-tune setting, since the whole point of this test is to note the effect of the single focus fine-tune calibration at different zoom settings. I shot another 10 shots at 24mm f/2.8, remembering to de-focus the lens before pressing the focus button to reestablish focus. I analyzed these photos in MTFMapper to find where the “typical” focus distance landed. 70mm f/2.8 focus results in MTFMapper The 70mm typical results are shown above. The plane of best focus was verified to coincide with the leading edge of the big target rectangle (I drew a vertical red line to show where best-focus is). The average MTF50 resolution of the little square left-edges is about 33 lp/mm. The average MTF50 resolution of the little square right-edges is about 36 lp/mm. The peak resolution was 37.5 lp/mm. 24mm f/2.8 focus results in MTFMapper The typical focus results at 24mm are shown above. The plane of best-focus missed the big vertical target edge by about 65mm (2.5 inches) at a focus distance of about 1 meter. To correct the missed focus, it would rquire a focus fine-tune calibration setting of about -6 on this camera. If I used this -6 fine-tune setting, then of course the 70mm focus calibration would be wrong. This is very, very irritating. Irritating enough for me to say a bad word. The average MTF50 resolution in the plane of the target edge (where the camera focus point was) is about 38 lp/mm. The actual plane of focus (indicated by the vertical red line above) has an MTF50 resolution of about 50 lp/mm, or about 30 percent higher resolution. This means that I lost 30 percent of resolution where I actually told the camera to focus! When I have the time and remember to do so, I change the focus fine-tune value to -6 when I am shooting in the vicinity of the 24mm focal length. Sometimes I'll try a small manual focus change instead. This is maddening to me, and fraught with error. The in-between focal lengths have varying degrees of focus error and their associated resolution loss. Conclusion The resolution loss your photos experience after zooming away from the calibrated focal length can be quite significant. Your very expensive lens may even be performing worse than a cheap ‘calibrated’ lens. You might even be blaming yourself for being a poor photographer who keeps missing focus. It’s really unfortunate that Nikon cameras and lenses don’t let the user calibrate focus at multiple focal lengths and focus distances. I don’t consider switching to Live View a solution; not for action shots, for sure. And please don’t tell me I need to stop down to f/16. And mirror-less cameras aren’t the savior, either. Sigma engineers noted this focus problem long ago, and fixed it by letting you calibrate their “global vision” lenses at 4 focal lengths and 4 distances per focal length. Tamron has since followed suit, so now their newer lenses have a similar calibration feature. This problem may force photographers to switch to lenses with smart, programmable firmware like Sigma and Tamron. I don’t think that Nikon has any plans to address the issue. I personally fixed the issue by buying Sigma lenses; and no, they didn’t pay me to say that.

Do you lose image resolution as you increase your ISO? Is there a maximum safe ISO that still retains good resolution? Does resolution loss happen before you get unacceptable image noise at high ISO’s? I had always assumed that image resolution would tank if I shot at high ISO’s, but I never got around to testing that assumption. It’s easy to notice noisy, grainy effects with high ISO, but it would be useful to know what happens with resolution, as well. I am especially interested in knowing if lens resolution test results are significantly impacted when I shoot in dim, versus bright, lighting conditions. The internet is full of discussions about higher ISO’s causing noise and less dynamic range. Image resolution impacts are rarely, if ever, discussed. Let’s find out if there are more image quality sacrifices being made than you think. If it’s not obvious, what counts in your photographs is the combined contribution of each element in the image chain. Lens resolution by itself isn’t going to be meaningful if you have image blur or a low sensor resolution, or possibly a high ISO. That’s why this article title refers to image resolution instead of lens resolution. Increasing ISO will drastically reduce your camera’s dynamic range, but shots ruined by blur are much worse than losing some shadow information or less clean details. As usual, I’ll be using the MTFMapper program to measure my resolution chart images. Studies have shown that its resolution results are just as valid as programs such as Imatest. The key to good resolution measurements is to use a large, high-quality test chart (besides using a sturdy camera support, careful alignment, and correct focus). To get measurements results that are reproducible by others, it’s also important to use raw-format, unsharpened image files. The Test I shot my test chart at ISO 100 through 6400 in 1-stop increments with aperture priority. I left the aperture at f/2.8 in each shot and only changed the ISO (so that the shutter speed would adjust for each different ISO). I haven’t bothered to show each ISO, because there was so little change between each test. I decided to just show the results at ISO’s of 100, 400, 1600, and 6400. I find quality beyond ISO 6400 to be unacceptable (mostly due to color noise and loss of dynamic range), so I stopped at 6400. ISO 100 resolution baseline The shot above is the un-sharpened resolution measurement near the very center of the test chart. The peak resolution is 2088 lines per picture height (Nikon D610). I used my Nikkor 24-70 f/2.8 VR lens at 50mm and shot wide open. The view shown above is at 100% magnification. ISO 400 resolution Except for a miniscule change of about 4%, the resolution at ISO 400 is the same as ISO 100. I wasn’t expecting much of a change with this modest increase in ISO, so the results seem consistent with expectations. ISO 1600 I can barely see a change at ISO 1600. There is some extra image noise, but it’s still mostly ignorable. There’s NO change in resolution from ISO 400. In the old film days, the picture would have already fallen to its knees at this point. ISO 6400 Image noise is rearing its ugly head at ISO 6400, but note that the resolution is about the same as lower ISO values! I was totally expecting resolution to crumble, but was pleasantly surprised that it didn’t. I’m not denying that dynamic range takes a huge hit, and color noise is now too objectionable for me to use ISO values like 6400 unless there is no other choice. One thing you don’t have to worry about, however, is resolution loss at higher ISO values. MTF contrast plot, ISO 100 The MTF contrast plots created in MTFMapper include a shaded band around the plot lines that show the range of individual measurements. You can think of this shaded band width as an indicator of image noise. MTF contrast plot, ISO 6400 Note the increase in thickness of the shaded bands for the higher ISO, which represent the individual chart edge measurements. You’ll always see this trend at higher ISO values. Also note, however, that the averages (the solid and dashed lines) show very little change at the high ISO. Summary Image quality is so much worse beyond ISO 6400 that I stopped testing at that point. I would have thought that resolution loss correlated closely with something like color noise or luminosity noise, but it certainly doesn’t. It’s comforting to know that my lens resolution test results aren’t impacted by ISO, since tests at f/16 often compel me to increase the ISO. I tend to avoid slow shutter speeds while testing resolution, due to the risk of vibrations affecting the resolution results. By the way, cameras that feature "electronic front curtain shutter" are wonderful in this regard; combining live-view with EFCS and a remote shutter release virtually eliminates vibrations. It’s a great time to be alive as a photographer. If somebody from the 1970s could see the kind of quality we’re getting today (at prices that are dirt cheap compared to the 1970s, too) I think that they would be absolutely flabbergasted.

If you have a less-than-perfect lens, you might find that stopping down the lens aperture can substantially change the amount of that nasty color fringing at the edges of the frame. The MTFMapper v7.29 program has some very sophisticated features to measure that color fringing (lateral chromatic aberration), also nicknamed “CA”. Lateral Chromatic Aberration CA is the ugly color fringing that you see in the frame edge when you photograph, for instance, tree branches against the bright sky. You may not notice it when you switch to a really good lens or stop the aperture down enough. The color of this aberration can vary considerably, depending upon your lens. Those color fringes are caused by the lens not bending the different colors of light equally; a ‘white’ light ray gets spread across a region of the sensor, instead of being kept as a point. This is different than axial chromatic aberration, where the different colors of light remain aligned relative to the lens axis, but get focused at different distances from the sensor plane. Many cameras will attempt to automatically remove CA, if you shoot in jpeg mode. Most modern photo editing programs will let you reduce, if not eliminate it, even if you shoot in Raw format. This CA removal usually costs you in resolution, especially at the frame edges. Lens reviews on the web lead you to believe that CA is a single number for a given lens, aperture, and sensor edge. False. To understand the true character of this lens defect, you can use MTFMapper, but only if you shoot in Raw format. You also need to use a suitable target. The same website that lets you download MTFMapper has files of resolution charts that you can print. Uncorrected Lateral Chromatic Aberration from a Poor Lens, Widest Aperture. The shot above shows how bad it can get with CA. This is example from a super-wide lens in the corner, and without any corrections applied. Suitable chart to use for your photographs The chart above shows you what a suitable target looks like. The bigger you can print it, the better. Wide-angle lenses particularly need large charts to get good feedback at realistic shooting distances (mine is 3 feet by 4 feet). Nikkor 85mm f/1.4 AF-S Lateral Chromatic Aberration In the testing that follows, I chose my 85mm f/1.4 lens. This lens was tested using a Nikon D610 that has an FX sensor with 5.95 micron pixels. The camera sensor pixel size needs to be entered into the program, or else the measurements will be incorrect. I am using the “micron measurements” program option, instead of the “pixels” or “radial offset percent” options. I use this option, so that it’s easier to directly compare measurements from other lenses or cameras. Nikkor 85mm f/1.4 with Nikon D610 (FX) Measurements at f/1.4 show many interesting things. First, notice how non-symmetric the readings are. Secondly, notice that the “Red versus Green” measurement range is entirely different than the “Blue versus Green” measurements. Nikkor 85mm f/2.0 with Nikon D610 (FX) Nikkor 85mm f/2.8 with Nikon D610 (FX) Nikkor 85mm f/4.0 with Nikon D610 (FX) Nikkor 85mm f/5.6 with Nikon D610 (FX) Nikkor 85mm f/8.0 with Nikon D610 (FX) Nikkor 85mm f/11.0 with Nikon D610 (FX) Nikkor 85mm f/16.0 with Nikon D610 (FX) Conclusions I found it interesting that the color shifting actually changed direction with the Blue/Green pixels, going from positive to negative, after stopping down to f/2.8 or beyond. I realize that every lens design may have unique characteristics, but it had never occurred to me that CA might have a cross-over response to aperture. This analysis is just one lens. The intent is to show you how an arbitrary lens can be evaluated to explore its limitations, at least in regards to chromatic aberration. The MTFMapper program has many additional capabilities, most notably resolution analysis in two dimensions. The 85mm’s Red/Green CA is essentially imperceptible at any aperture and very different than the Blue/Green response. Most lenses probably favor one color pair over the other. This is probably a good test to spot poor lens assembly or damaged lenses. Plots that aren’t reasonably balanced about the lens optical center could be easy to spot, indicating a problem such as a tilted lens element. As I suspected, stopping down the aperture definitely helps reduce CA, at least for this 85mm lens. The whole point in using the free MTFMapper is to enable photographers to evaluate their own lens characteristics. Since this feature has just become available in MTFmapper, I have a lot of exploring to do. Any broad conclusions I draw from studying a single lens will probably require many future revisions. This new CA feature has definitely given me extra food for thought.

This review is mostly concerned with the lens MTF50 resolution performance and how well the lens autofocuses. I’m not overly concerned with minor lateral chromatic aberration (since the software fixes it), trivial distortion (software can fix it), and some vignette issues for full-frame users (software can fix it, too). What software can’t fix is a lens that focuses poorly or has weak resolution. The Sigma 150-600 Contemporary lens delivers where it counts. All across the field of view. And it delivers with the aperture wide open (which is pretty much where I park it). This is a “single lens copy” test, so your mileage may vary. I know, you’re suspicious that the Contemporary resolution is garbage compared to the Sports version; read on. I’ve spent the better part of my life wanting a really big lens that wasn’t crap or cost as much as a car. Here it is. It’s liberating to frame a subject the way I want, and actually have some elbow room in focal length left over. For those of you that want to shoot eagles in a dive with a 600mm prime lens, good luck finding it looking through an 11-pound straw. You want a zoom to find the thing and then zoom in. This is among the smartest lenses on the planet to date. Don’t get this lens without the Sigma USB dock and its Optimization Pro program; you’ll regret it if you do. The dock will let you properly calibrate focus at 16 combinations of focal length and distance; all zooms need this capability, but all of the other manufacturers have done nothing about it to date. If you read a review mentioning something like "it focuses well at 40 feet but not infinity" then that probably means that they didn't bother to carefully calibrate the lens at each focal length and distance setting using the Sigma USB dock. Don't be lazy! I hope you’re ready for a 4 1/2-pound lens, though (with hood). I can’t imagine hauling around the ‘Sports’ version all day, which is about 7 pounds (with hood). You might try renting a beast like the Sports version and carry it for a whole day before you buy it. Maybe you shoot in rain and dust all the time and need the Sports version; it’s a heavy price to pay, though. Sorry about the pun. I mostly bring a monopod with a gimbal head and an Arca-Swiss plate when shooting animals. You can shoot all day, properly balance the lens at every focal length, and most importantly not suffer while trying to hold this thing steady. I have lasted maybe an hour with the lens hand-held before I was ready to call it quits. I typically use the “OS2” stabilization setting (panning) instead of “OS1” (general hand-held) in poor lighting on a monopod. If I move the lens both vertically and horizontally, though, then I need "OS1" set (until about 1/1000 second, beyond which it should be turned off). The lens center of gravity shifts quite a bit while zooming, hence the Arca-Swiss plate. 3-17-2017 Update After the firmware update from Sigma (using the optional USB dock) you no longer need to turn off optical stabilization when using high shutter speeds. Yes, you’ll need to stop using ISO 100 with this lens. Get over it. Even the people shooting with the $10K+ super telephotos have gotten over it. Learn to love f/6.3. Here’s a word or two about “plastic”. Some of the finest and most high-tech materials in the world are plastic. They didn’t make this lens out of melted milk jugs. They use thermally stable composite; it’s tough and has excellent dimensional properties, even over a wide range of temperatures. And it makes the lens light enough that you can actually walk around with it. I used to be jealous of those guys with the little wheels on their tripods and their 400mm f/2.8, 10 pound lenses. Careful what you wish for. Just don’t drop the lens. Same goes with metal lenses; drop a big lens on the sidewalk and it’s a goner, period. I don’t see too many plastic football helmets breaking, and I don’t see too many “quality metal” football helmets, either. Sigma gives you a neck strap that attaches to the tripod collar. It might seem a little geeky, but it is a great insurance policy. I use it, especially when I’m adjusting the monopod leg when it’s attached. And never, ever hold this rig by the camera; bad things will happen. I also use a Cotton Carrier to carry the lens on a waist belt when I’m not going to be shooting for a while; it totally saves your back and neck. The lens comes with a zoom lock, so it won’t creep out to 600mm while you’re walking with the lens pointed down on the waist belt; it doesn’t creep getting a moon shot over head if you lock it, either. Nice. The lens hood is bayonet, which is always my favorite. It reverse-mounts for storage, which is exactly what you want. The lens is breathtakingly long at 600mm with the hood on, but what did you expect? You always want to use the lens hood; the longer the focal length, the more important it is to use the hood. Lots of glass in that lens. You also get a pretty nice storage case with the lens. I swear that the Sigma designers must actually use their lenses. What a concept. You have to wonder about some of the other manufacturers. One note about the zooming. It’s Canon-standard direction and opposite the Nikon-standard. Not much of a problem when you’re sticking with one lens, but muscle memory goes haywire when using another lens on the same day. Sigma even offers a service to change the lens mount if you have a mid-life crisis and switch from Canon to Nikon or whatever. It’s my understanding that Canon and Nikon do not offer this service. Duh. Sigma 150-600 Contemporary at 600mm on gimbal head Lens was elevated a little higher than ideal in the gimbal so you can see it better. Properly balanced using Arca-Swiss plate. Note the supplied neck strap Autofocus I prefer to use the camera in AF-C mode and a separate focus button. This lens focuses quickly with absolutely no chatter using the factory default AF algorithm. Lenses with focus chatter (like my Nikkor 70-300 AF-S) drive me crazy, especially with their auto-50%-un-sharp-rate. Three different autofocus algorithms are available with the Sigma Optimization Pro and USB dock. Choose between Speed Priority, Standard (factory), or Accuracy. I wasn’t happy with the repeatability of Speed Priority, and the factory setting works very well for me. I’m leaving this customization alone and sticking with the factory setting. I have, as a matter of fact, assigned “C1” to be Speed Priority and “C2” is Accuracy, but I am presently leaving this custom switch OFF, to get the factory default Standard setting. Sigma is bound to optimize their autofocus algorithms more in the future, so I may re-evaluate my decision to avoid using Speed Priority. You’ll probably want to use the “Focus Limiter” switch to get a more substantial speed-up of autofocus without sacrificing accuracy or repeatability. Just don’t forget when you decide to limit the focus range. I’ve missed several shots when a subject moved just outside the range setting. Update 3/21/2016 Sigma released new firmware that makes focus between 20% and 50% faster. I told you so. Sigma did it for FREE, too. The USB dock just paid for itself yet again. I tried it out, and the focus really snaps. My test shots (not new resolution test charts, though) don't show any obvious loss in sharpness with this speed increase. I found the focus motor to be remarkably quiet. Always a good thing. I focus-calibrate the lens and use the Sigma USB dock to save the data before I do any resolution testing. Tests are done with stabilization off, contrast-detect autofocus (mostly), and I use the infrared remote with the mirror up. I only use RAW, unsharpened pictures for measurements. Testing was done using a Nikon D7000. I have been amazed how close phase detect focus compares to contrast detect focus with this lens. Newer cameras will only be better. Sigma dock 16 focus calibration settings. Your settings will be different. It’s a ton of work to fill in the 16 calibration settings with verified values; there were iterations galore. You’ll thank yourself once it’s done, though; no pain no gain. Maybe some day Sigma can write these values for us at the factory, since they claim to measure every lens MTF anyway for quality control (I bet they don’t do it at all 16 combinations, though). Note that the “Rewriting” button above needs to say “Save”. I wonder how well I would do if I had to label the buttons in Japanese. Focus Limiter Range You can tailor the distance ranges applied to the Focus Limit switch using the USB dock. You probably don’t want to alter the “Full” range setting (minimum focus to infinity), but that’s just me. You might want to change the “10m-infinity” setting to actually use something like “5m-infinity”, though. The focus limit switch settings on long focal lengths can be pure gold for minimizing the time to acquire focus. I’d try this feature first before I’d look at the “Speed Priority” autofocus algorithm. Don’t take my word for it, though; try it for yourself. OS Setting (Vibration Reduction) Customization It claims to alter the amount of visible vibration reduction in the viewfinder (as opposed to actual sensor anti-shake). It presumably provides the same level of anti-shake effect in the actual photographs, regardless of the setting. Honestly I haven’t experimented with this, and the factory setting works well (but the subject does move around more in the viewfinder than I’m accustomed to seeing with Nikon VR in effect). Remember to always turn off the OS when shutter speeds go faster than 1/500 (or at least 1/1000). Do as I say, not as I do. The programmable settings are referred to as “Dynamic View”, “Standard”, and “Moderate View”. I’m personally able to get about 3 stops of shake reduction with the factory setting. Since I mostly use a monopod with this lens, I use the OS-2 (‘panning’) versus the OS-1 (‘normal’) mode in poor light. If I have any vertical motion, however, then the best setting is OS-1. Most reports suggest that the OS provides about 3 2/3 stops enhancement. I guess I shouldn’t have had that last cup of coffee before I tried this. I have found that the shutter range between 1/500 and 1/1000 is 'murky'. Generally I have better results with stabilization ON here; beyond 1/1000 shutter, active OS makes resolution drop about 9%. 3-17-2017 Update: The firmware update fixes the problem with using stabilization and high shutter speeds. It also increased focus speed. "Moderate View" gives the best stabilization effect, although "Dynamic View" provides the smoothest viewfinder effect. See my article here. I was correct about improvements in future firmware updates! This feature (finder view and sensor anti-shake) is likely to get improved in future firmware updates, since stabilization is a mix of both lens hardware and firmware algorithm cleverness. Resolution Testing I hate those lens reviews which grade lens resolution with adjectives like “good”, “fair”, and “excellent”. What the heck does that mean? I want real numbers and I want to see real pictures of things I’d actually bother to photograph. I want to see sharp eyes, fur, and feathers. Does the camera sensor matter? Yes! Tests shown below on a Nikon D7000 can be improved by about 20% by switching to the Nikon D7100, for instance (I tested it). I use a (free!) program called MTF Mapper from here to measure lens resolution. The download site also has files for printing out the resolution targets (mine are A0 size on heavy glossy paper, mounted on a board). This program is covered in more detail in another article, but suffice it to say that this is really great stuff; it’s comparable to ‘Imatest’ in the quality of the MTF measurements, and it uses the “slanted edge” technology similar to ‘Imatest’, also. The author of MTF Mapper, Frans van den Bergh, really knows his stuff. The MTF Mapper documentation he wrote works best for people with an IQ around 180 and above, I suspect. The "MTF" refers to Modulation Transfer Function, which refers to how light/dark transitions happen. "MTF50" refers to the highest line frequency (line pairs per millimeter) you can have before 50% of the contrast is lost. Values above about 30 lp/mm are considered pretty good, and anything above 50 lp/mm is outstanding. You can judge for yourself how the sample photos in this article relate to the MTF50 numbers I measured. Always keep in mind that this is just ONE lens sample; I guarantee your mileage will vary. Some physics facts first. The 600mm resolution isn’t going to be as good as 150mm, even if the optics are “just as good”. Vibrations are magnified and the extra atmosphere between the lens and the subject will cause a little shimmer. Just saying. The chart design used for resolution tests orients all of the little black squares to be ‘slanted’ but they’re generally aligned in meridional and sagittal (think spokes on a wheel) directions to correlate better with the usual MTF plots you’re familiar with. There’s often a dramatic difference in sharpness between these two directions, and the chart photographs show it clearly. The meridional/sagittal differences are what “astigmatism” is all about. This lens is better in the sagittal than the meridional direction when you get away from the lens optical center. BTW, there is a mild “X” pattern that shows up in many of the 2-D focus plots; Frans van den Bergh has shown this to be a consequence of the square shape of the photo sites on the camera sensor itself. The MTF50 values are only very slightly affected by this (about 2% error along the “X”). You can get a load of how smart Frans is by reading his discussion of this phenomenon here. You might want to grab a cup of Joe first. If you think that the resolution test values should match the manufacturer MTF plots, think again. You might want to consult Roger Cicala’s article here to get a rude awakening. BTW, Roger uses “tangential” instead of meridional terminology. What the resolution target looks like. You’re probably wondering by now if I’m ever going to get around to some actual resolution results. I am, but I just wanted to provide some background into why the resolution results have actual validity (for this particular copy of this lens model). I hate “secret science” and hand-waving claims. I guess it’s just the engineer in me (I’m a mechanical engineer and software developer). I want you to be able to do the same tests as me. Thanks again, Frans. 600mm f/6.3 Note peaks at almost 40 lp/mm Note the little red edge measurements in the plot. The sagittal measurements are quite a bit better than the meridional (tangent) measurements. Note the EXIF data shows this was shot at about 62 feet (18.8m). This is a pretty realistic distance for a focal length like this. Farther than most testers would attempt. Tests were done in “Live View”, contrast detect, IR remote. The 600mm f/6.3 test above was 1/640s, ISO 800, +0.7EV exposure compensation, lens vibration reduction OFF. This is approximately EV 12.3. All subsequent tests were ISO 800 to maintain high shutter speeds. Resolution on this camera drops off after about ISO 1600. 600mm f/6.3 whole field of view. Sagittal is better than Meridional 600mm f/8 resolution not much different 600mm f/6.3 Lens Center I know, I know. There’s a little crease in your chart! Fortunately, it didn’t have any effect on the measurements. 600mm f/6.3 APS-C Corner. Note Sagittal much better than Meridional 500mm wide open 500mm wide open 500mm f/8.0 500mm f/8.0 400mm f/6.0 A bit of a surprise seeing this much astigmatism here (look at the wide vertical spread on those data points). Nonetheless, pictures at this focal length look pretty nice to my eye. 400mm f/6.0 whole sensor 2D view It’s the meridional measurements on the sensor edges are bringing down the averages. The center is really, really sharp. 400mm f/8 400mm f/8 300mm wide open. Pretty awesome. 300mm f/5.6 Flirting with 50 The test chart A0 size wasn’t quite large enough to fill the frame at this distance. 300mm f/8. That’s what I’m talking about 300mm f/8 200mm wide open Note the distance change for 200mm and below. The chart is back to filling the frame. 200mm wide open 200mm f/8. Look at all those red specks over 50 200mm f/8 150mm wide open 150mm wide open 150mm f/8 awesomeness It’s a crying shame that I almost never use 150mm (except to locate the target before zooming in). I bet it would make stunning portraits, but depth of focus might be a bit too deep for my taste. 150mm f/8 Sample Pictures Cheetah Deep Shade 500mm f/6.0 1/250 ISO 2000 stabilization OFF Cheetah crop to see eye detail. Enough said. Grizzly 240mm f/5.6 1/200 ISO 1250 stabilization ON Hummer 480mm f/6.0 1/800 ISO 1000 stabilization OFF Lioness 440mm f/6.0 1/500 ISO 1600 stabilization ON Lion 600mm f/6.3 1/1000 ISO 1600 stabilization OFF. Nice background blur #review

This 2013 camera was the mirrorless version of the Nikon D7000 from 2010. I thought it would be interesting to take a look at this camera to see how it has fared with time. Let’s face it; most digital equipment ages very badly. The Coolpix A has the same DX sensor (except special micro-lenses on the pixels) and it actually cost about the same ($1,100 US) versus the D7000 ($1,200) when it was new. I’m not much of a fan of this kind of camera design, for a couple of reasons. The Coolpix doesn’t have a viewfinder; it only has an LCD screen (very, very bad for action or sunshine photography). The Coolpix also has a fixed 18.5mm f/2.8 lens; you can’t zoom it or interchange it with anything else. You also can’t put any filters on the lens, unless you buy an adapter to fit 46mm filters. The field of view is equivalent to a 28mm lens on FX. I have an LCD viewfinder (made by Xit) that I can use for this camera in the sun. This viewfinder is actually bigger than the Coolpix, and goes against the whole reason for getting this tiny Coolpix in the first place. So why would anyone get this camera? Ironically, you’d get it for that 18.5mm lens. It’s really, really good. The resolution is simply sensational, and it has virtually no distortion. I sorely miss vibration reduction, however. Coupled with the absence of an optical low-pass filter on the sensor, you’ll probably get sharper shots with this camera than you can achieve with a DX DSLR. There is a manual focus ring at the base of the lens (it’s rotation-speed-sensitive on focusing rate). You can stop down to f/22.0, but resolution is already mostly ruined by f/16.0 because of diffraction. You can focus down to about 20 inches. I haven’t made much notice of vignetting; I adjust it in photo editors if I want more or less of it. If you slide a little switch on the left side of the camera to the “tulip” position, the lens focus is in macro mode, and you can focus down to 4 inches. This same left-side slider switch has an “MF” position for manual focus, which causes a vertical distance scale to pop up on the screen to help you both focus and also advertise that you’re in manual-focus mode. You can press the “+” magnifier button while focusing to zoom in the LCD screen and easily obtain critical manual focus. If you then press “OK”, it goes back to a full-screen view. If you’re a manual-focus type person, this scheme is rather nice. In full manual exposure mode, the rear dial around the 4-way controller controls the aperture, while the top dial controls the shutter. In aperture mode, the top dial takes over control for the aperture. The Coolpix can fit in your (jacket) pocket, and it’s virtually silent as you shoot. The reason you’d shoot with this instead of your cell phone is because of the sensor. This 16MP DX sensor has 4.77 micron pixels, whereas typical cell phone cameras have 1.4 micron pixels. In terms of light-drinking surface area, that means the Coolpix A has 11.6 times as much pixel area as that cell phone. The shutter only goes to 1/2000 second, but for a 28mm-equivalent lens, I suppose that’s plenty fast. You get a maximum of 30 seconds, plus “bulb”. Since this is a mirrorless camera, the focus doesn’t need any calibration. The focus works via contrast-detect; it’s slow, but it’s quite accurate. This also contributes to very sharp photos. It only weighs 10.6 ounces, which actually conspires against it for steady shooting (it has very little inertia). It’s a magnesium and aluminum camera body, although I wouldn’t call it “rugged”. It has a cheesy little vertical bar that they call a “grip”. I’m used to the really good grips on Nikon’s pro and enthusiast cameras, so this camera is very disappointing in that regard. It only accepts a single SD/SDHC/SDXC card. The sensor supports a native ISO range of 100-6400, but please, please stay away from 6400. You can actually crank it up to 25,600 (Hi-2) if you want to emulate the painter Georges Seurat. That LCD display is 3” and 920K dots. The 920K specification sounds pathetic, compared to modern screens, but the view actually looks pretty good. Nikon offered a hot-shoe-mounted optical viewfinder (DF-CP1) that sold for a whopping $450.00 US! I wonder how many of those they sold. It also makes the camera look like something out of the 1950’s. The camera can only shoot at 4 fps continuous; modern cameras really spoil us with speeds that are about double this pace. Time marches on. Its EN-EL20 battery is rated at 230 shots. You can shoot 1080p movies at 24, 25 or 30 fps if you’re interested in video. It does have a stereo microphone and mono speaker. Your cell phone is probably a better choice. The Coolpix A sports the “U1”,”U2” user mode settings, which I will always consider to be vastly superior to the “pro” camera memory banks. I still question if a single Nikon engineer has ever actually taken a photograph. Don’t get me started. If you use built-in flash, this camera has a joke of a pop-up flash that sticks up a little over a quarter of an inch. Amazingly, it doesn’t readily produce the dreaded red-eye. The pop-up flash cannot act as a commander to other flashes; oh, well. You can slip the standard flashes into the hot shoe, such as the SB-600 and SB-700. You can use the cheap Nikon ML-L3 infrared remote to control it, thank goodness. It’s a bummer that the only IR receiver on the camera is on its front; I personally want to use a remote from the rear of the camera about 95% of the time. The Redeeming Feature: Lens Resolution The following charts show what kind of resolution performance you can get out of this lens. These are taken from un-sharpened 14-bit Raw pictures. MTF50 resolution lp/mm f/2.8 The resolution numbers are just astonishing. And this is with the lens wide open. Excellent, except in the corners. MTF50 resolution lp/mm f/4.0 This is nearly as good as I have seen from the best lenses you can get. Just a slight drop-off in a couple of corners. I think that the sagittal-direction central doughnut pattern is due to the lens aspherical element. MTF50 resolution lp/mm f/5.6 Great resolution throughout. MTF50 resolution lp/mm f/8.0 MTF50 resolution lp/mm f/11.0 Diffraction is starting to affect the resolution by f/11, just as you would expect. It’s still extremely good, however. MTF50 resolution lp/mm f/16.0 Diffraction is really starting to kill resolution at f/16. I don’t have the heart to try measuring f/22. MTF contrast plot The following plot was actually measured, and isn’t the usual “theoretical” MTF contrast plot that manufacturers publish. f/2.8 Contrast at 10, 30, 50 lp/mm Lateral Chromatic Aberration Lateral Chromatic Aberration f/2.8 Even wide open, CA is already a “don’t care”. Lateral Chromatic Aberration f/4.0 Lateral Chromatic Aberration f/5.6 Lateral Chromatic Aberration f/8.0 Lateral Chromatic Aberration f/11.0 Lateral Chromatic Aberration f/16.0 Samples Sherman building, built 1857. Washington DC. f/5.6 1/800 ISO 100 Rose Chapel built 1870, Washington DC. f/5.6 1/250 ISO 200 Lincoln life-sized statue by Lincoln’s cottage, Washington DC Washington DC historic house Potato Chip Rock, Poway, CA. It's really that thin. San Diego skyline panorama. Stitched with Lightroom. f/2.8 1/800 ISO 100. Bokeh is decent in most circumstances. Color sketch, in-camera retouch menu option. Slightly cheesy. Summary In terms of attractive features, the Coolpix A has quite underwhelmed me. I think that the D7000 had far more features and flexibility for about the same price. At the same time, the Coolpix is very, very portable. I imagine that Nikon expected photographers to slip this camera into their pockets (which you actually can) to always have gear available. Cell phones really ruined those plans, however. You might think of the Coolpix A as a cell phone without the phone or the apps, which I’m sure is the typical Millennial opinion. You would get this camera for its lens; it won’t disappoint if you happen to like this focal length. The Coolpix A is an interesting mix of cheesy and nice. I think of it as a ‘tourist’ camera. To give credit where it’s due, this camera hasn’t broken down in any way over the years. It is a pretty well-made camera. I was a skeptic of its auto-extending lens (when you turn it on), but it still works like new. When it’s off, there’s no lens to bump and it keeps the front lens surface clean. It’s kind of nice to not worry about a lens cap. I still take this Coolpix A out with me occasionally, when I don't want to lug any "real" camera gear along. My cell phone just doesn't have the satisfying 'feel' of a camera, and it's sensor can't compete with my Coolpix in really dim light. I never thought that I'd hold onto this camera for so many years, but I still don't want to let it go.

Anybody who has followed my site knows what a fan I am of the MTFMapper program. Frans van den Bergh, the author, has expanded his program’s offerings (version 07.29) to now include lateral chromatic aberration (CA) measurement. His free program can be downloaded from here: If you’re interested in axial chromatic aberration, this same program can help you measure that, too. Check out this article What Does Lateral Chromatic Aberration Look Like? Lateral chromatic aberration rears its ugly head The shot above shows typical CA. It’s those purple edges you see mostly in the corners of your photos, especially when you have a dark object against a light background. Notice how those purple edges aren’t the same in the radial/sagittal (think wheel spokes) direction versus the tangential/meridional direction. Most lenses show this CA defect much more in the tangential direction. The colors of CA can look different, depending upon the lens. The new CA measurement feature gives you a pair of measurement plots that contain Red/Green and Blue/Green analysis. Since the camera sensor has a Bayer grid of red, green, and blue pixels, the program takes advantage of this extra information. If you’d like to be able to attach useful numbers to this coloring defect, in order to compare one lens to another, or to compare different aperture settings on the same lens, then this program feature is for you. My absolute worst lens for chromatic aberration: Rokinon 8mm When it comes to CA, a lens that has an embarrassing abundance is my Rokinon 8mm fisheye. As you can see above, it’s much worse in the blue-green region than the red-green region. The plot above shows typical output from this new program feature, where I configured it to measure CA in “microns”. Notice in the chart above that CA isn’t perfectly symmetric about the lens center. Most web sites will just give you a single number for this measurement, but it just isn’t that simple in real life. The plot ‘negative’ measurements certainly don’t mean something like “less than no CA”. Negative measurements just mean the relative shift of one color versus another. With many lenses, this color shift can even transition from negative-to-positive or positive-to-negative. A measurement of zero is still the lens designer’s holy grail. To get the best accuracy in your measurements, be sure to carefully focus the lens and get the chart perfectly flat and parallel to your camera sensor. The shot above was done with a D7100, which has 3.92 micron pixels. The worst measurement here (-12) is equivalent to 12/3.92 or 3.06 pixels. There are multiple units that you can select to measure CA, and those ways are discussed next. I really love the perspective abilities that this fisheye lens gives me (especially after I remove the curved lines in Lightroom) but I don’t love its CA. Select how to measure CA You have the option to measure lateral chromatic aberration in units of microns, pixels, or “percent of radial distance from the lens center”. You will find that different web sites will measure CA in different ways, and this gives you the ability to compare your own results against those web sites. Bear in mind that the “absolute” CA measurement is in microns, since this removes the camera sensor pixel size from consideration. If your goal is to compare different lenses on different cameras, this would be the best choice. You’ll need to remember to enter the correct sensor pixel size in the Preferences dialog, or else your measurements will be garbage. Set the pixel size for micron measurements The units of measurement for lateral chromatic aberration are in microns if you tell it the sensor pixel size. If you don’t select “Line pairs/mm units”, you will get measurements in “pixels” instead of “microns”. Note that the “CA display type” doesn’t have a “microns” option in its list. Preferences to get CA “pixel” measurements Preferences to get “Radial %” measurements A word of caution when using new resolution charts New resolution chart style (with annotations on it) The chart style above may not produce any chromatic aberration plot output unless you deselect the option to use “Line pairs/mm units” in the Preferences dialog. This means you can still get pixel or radial percent output. This limitation will probably be eliminated in the next release of MTFMapper. I notified the author about finding this issue. Addendum 8-17-2020 Frans did fix this issue with the 07.30 version of MTFMapper. The new chart style works just fine, even when using the "Line pairs/mm units". Preferences dialog for new resolution chart style The shot above shows how I specifically avoid Line pairs/mm units when using the ‘new’ resolution chart style. With this setting omitted, my CA plots can be successfully created. The “old” printed chart to use for measurements The same web site where you download the software also has PDF files of various test charts that you can print out. The chart that I used to make the chromatic aberration measurements looks like the one shown above. To get the most reasonable measurement results, you’ll want to print a large chart. My chart is 36 inches X 48 inches. The chart style shown above works for all of the chromatic aberration plot output options. As I already mentioned above, I tried shots using a newer-generation resolution chart (it has an hourglass shape in its center) and the software refused to make chromatic aberration measurements. When I stopped selecting the “Line pairs/mm units” option in Preferences, it started working with this chart style. I’m glad that I still have both kinds of charts. You can just multiply any “pixel” units by the number of microns per pixel of your sensor to convert into microns. For instance, the Nikon D850 has 4.35 microns per pixel, so 2 pixels of chromatic aberration would be (2 * 4.35) or 8.7 microns. To display the chart measurements, click on the “chromatic aberration” option after opening and processing your chart photos. Remember to use “Raw” format photos, because your camera will probably attempt to remove any chromatic aberration if you shoot in “jpeg” format. I suppose that if you took a shot in both Raw and jpeg (with corrections active), you could evaluate just how well your camera can correct for CA. You’ll find that lateral chromatic aberration decreases as you stop down your lens aperture. The MTFMapper program will let you now explore how you can control this lens defect with your lens. Keep in mind that you’ll get different measurements if you shoot with DX versus FX format; FX will look worse than DX on the edges, of course. Rokinon 8mm f/3.5 chart A note of caution: I found out that the use of “stereographic” lens distortion correction (in the Preferences dialog), which should normally be used for my 8mm fisheye, caused problems for this version of MTFMapper. If I left the default distortion correction at piecewise quadratic, it could successfully complete the CA plot. The measurement results for this fisheye lens may be suspect, since I was forced to use a non-optimal distortion correction option. Addendum 8-17-2020 Frans did fix this issue with the 07.30 version of MTFMapper. The "stereographic" lens distortion selection now works for all of the plot types. The vast majority of lenses work just fine in the analysis (I typically use piecewise-quadratic distortion correction). I just thought that I should mention that extreme-perspective specialty lenses might not be handled properly in this program version. I imagine that this shortcoming will be addressed soon. I have the bad habit of stress-testing programs to look for any weaknesses in them. I always try to notify Frans if I notice anything amiss, so that he can analyze and address any issues; Frans has always been extremely responsive. He is already working on this distortion correction issue, which he thinks is associated with the “Bayer channel” selection in the Preferences dialog. Much less chromatic aberration when stopped down If you compare the f/8.0 plot of this Rokinon 8mm with the f/3.5 plot near the top of this article, you can see how much improvement there is when you stop down. Having the CA measurements at different apertures, in addition the standard resolution measurements at those same apertures, you’ve got a lot of good information to determine the optimum aperture to use on a particular camera/lens combination. Conclusion Lateral chromatic aberration measurement is a great addition to the MTFMapper program. Even though photo editors such as Lightroom can mostly remove this lens defect, there is still a slight cost in overall lens resolution to do so. If you’re comparing two lenses that are basically locked in a tie, maybe this CA measurement feature can help to cast the deciding vote. Frans is now accepting PayPal donations at his website http://mtfmapper.blogspot.com/. I encourage you to show Frans your support for his continuing hard work and excellent product. No, he didn’t ask me to mention this. I just think that it's to everybody's benefit if Frans can keep his program current and make it even more powerful.

This is the mirror lens design, called “catadioptric”, which bounces light twice inside the lens. The goal of Nikon lens designers was to make a telephoto lens that was as small and light as possible. This is essentially the same optical design as the Hubble telescope. All designs involve trade-offs, and this design has huge trade-offs. On the plus side, the lens has acceptable sharpness, weighs next to nothing for its focal length, has essentially zero chromatic aberration, and it’s cheap. On the negative side, its fixed aperture is slow, there’s lower contrast, and it has a minor hot spot in the center. With the miracle of digital processing, most optical drawbacks can be minimized or eliminated. One optical issue, however, is this lens’ biggest weakness: doughnut-shaped bokeh. Reflex-Nikkor C 500mm f/8 My lens copy is from 1981. This is from the Nikon era of supreme build quality, so the lens works as well as when it was brand-new. It comes with 39 mm rear filters, including yellow, red, orange, neutral-density, and the L37c UV. A filter is required for the optical design, so I leave the L37c mounted. It comes in a nice hard-leather case, and the filters fit inside the case lid. The lens focuses down to 13 feet, and weighs 2.2 pounds. The real transmission of this f/8 lens is closer to f/11. It comes with a built-in tripod mount, with a button to switch between horizontal and vertical. It’s 3.6 inches in diameter and 5.4 inches long (6 inches with its included screw-in lens hood). The manual focus rotates about 180 degrees, and mine is silky smooth. You need this kind of focus throw, due to its long focal length and narrow depth of focus. The “C” in the lens name indicates that the optics are fully multi-coated. Back in the day, this was a big deal. These lenses presently sell for about $300.00 US in pristine condition. Less than the sales tax on most big telephotos. Like I heard once, it’s dollars to doughnuts. It should go without saying that you need to stick with shutter speeds above 1/500 second. The lens has little inertia, so you need to watch out for vibrations. With modern cameras, ISO is no longer the huge problem that it was in film days, thank goodness. Catadioptric optics with two mirrors to bounce light The optical design shows how it’s great for minimizing physical length, but it also shows how the front mirror blocks a huge amount of light from entering the lens. Mirror lenses are inherently dim. This is one of those “Non-CPU Lens Data” camera setups, which lets you use aperture-priority automatic exposure. I tested this lens on the Nikon D610. Lens Resolution I mentioned above that the lens has acceptable sharpness. Maybe I should have said ‘barely acceptable’. The peak MTF50 values on my D610 were 31.8 lp/mm, where 30 lp/mm is the lower end of acceptable resolution. Corners and edges were typically around 22-27 lp/mm, which is sub-par by today’s standards. You really notice how the center of shots are brighter than the edges; it has a different character than normal vignetting. This is fairly simple to fix in post-processing. I used “live view” at 100% to try to get the best focus on the resolution chart. I leave the shots as un-sharpened raw for the MTFMapper resolution software analysis. Nikon D610 MTF50 results The resolution results are interesting, in that the meridional and sagittal directions look almost like mirror images of each other. Sort of a yin-yang. The peak MTF50 of 31.8 lp/mm equates to 1526 lines per picture height for this camera sensor. Honestly, nearly all modern lens designs will smoke this lens when it comes to resolution. MTF 10-30 Contrast plots You can really see the low-contrast characteristics of the lens in this plot. Very unusual to see the edges seeming to improve compared to the center. Overall, results are underwhelming when compared to modern lenses, but not by a huge amount. Samples Humming bird looking at doughnuts The out-of-focus background has that strange doughnut characteristic. Providing full disclosure here, this is the sharpest out of about a dozen shots I took. Depth of focus is razor thin, and auto-focus was sorely missed. You’ll probably want to leave your camera on “continuous-high” and shoot away as you tweak focus. Auto-focus spoils you rotten. It removes the biggest challenge associated with long lenses. Technology is a wonderful thing. On the other hand, the humbling experience of focusing a big lens yourself can be an interesting challenge. Protea The out-of-focus Protea reminds me of sea anemone. Again, a pretty strange effect. Not a terrible effect, just different. Notice the center is brighter than the edges; many times this is just fine and you can leave it as-is. Conclusion This lens is one of those things that is an acquired taste, which most people will never acquire. If you really, really need to pack a long lens into a small space, then this is about as small as you can get. I have used this lens backpacking; I would never be able to haul my big telephoto on those trips. Long lenses are almost unusable without auto-focus, as far as I’m concerned. When you combine the manual focus with the strange doughnut bokeh, this lens just has too many strikes against it for most uses. It’s easy to see why Nikon and most other lens makers have abandoned this kind of design, auto-focus or not. #review