It’s inside every fiber of my being to never, ever take a shot with my camera unless it’s either firmly hand-held or secured atop a tripod. What kind of pictures can you get when you finally get brave enough to let go and lay your camera down? I decided to try some bug-perspective pictures right inside some plants. I haven’t gone totally crazy, though; I brought along a little towel to keep dirt and moisture off the rear of my camera as I laid it down on the ground or inside the nook of some branches. The bunched-up towel was also handy to help aim the camera. Aloe with 8mm fisheye lens I used my 8mm Rokinon fisheye at a short focus distance and stopped down the aperture to f/16. I also used a self-timer or remote control so that I could get out of the way during the shot. This definitely isn’t a general-purpose lens, but it can make great photos with extreme perspective. The effect I’m after here only works with super-wide lenses. You could get improved focus depth using focus-stacking software with multiple shots, but this single-shot technique works pretty well (and avoids problems with wind). For some shots, the 180-degree view and curved lines were a bit much, so I used the Lightroom “lens profile corrections”. This lets you get the lines straight (it becomes a rectilinear lens), at the cost of about 2 millimeters of focal length. I also went straight from Lightroom to my HDR Efex Pro 2. People either love or hate this stuff; I’m in for former group. I waited for cloudy conditions; I think the sky looks far more dramatic with heavy cloud cover, especially with HDR. Camera lying on a protective towel The shot above shows how I would fluff up a hand towel under the camera to help line up the shot. A beanbag would work even better for this, if it’s not too thick (bugs are short). Aloe Ferox from a bug’s perspective Camera resting inside a Protea bush Inside a succulent plant in full bloom If you constrain yourself to tripods or hand-holding, you’re going to miss out on some very interesting picture opportunities. Other than a super-wide lens, you don’t need any special equipment to try this. You obviously aren't constrained to just laying the camera on its back. The key is to get low, close, or underneath. Find a way to get your camera to somewhere you can't get your eye. Make sure you don’t get too cocky and rest your expensive camera on a flimsy branch that can snap off with the first light breeze. You might even consider using a safety line or camera strap to connect your gear to a sturdy branch so it doesn’t accidentally come hurtling out of that tree. Happy shooting.

Ever wonder how your camera and lens focus speed changes with light levels? Everybody knows that focus gets slower in dim light, but by how much? Focus speed is primarily a function of three things. First, the camera tells the lens what distance to focus. Second, the lens hardware (and firmware) has its built-in capability to respond to focus requests. Third, light levels dictate the quality of focus feedback the camera gets to work with. Bad light equals bad focus feedback. There are, of course other variables that can influence focus speed, such as the ambient temperature and the subject contrast. My own tests are done in good conditions (around 70F to 80F) with a fully-charged battery and a pretty high-contrast target. A fast-focus lens Any focus speed measurement is only valid for a particular camera and lens combination. For the tests that follow, I used my Nikon D500. This camera seems to behave almost exactly like my D850 in regards to focus capability. I tested three lenses: my Sigma 70-200 f/2.8 Sports (at 200mm), my Nikkor 85mm f/1.4 AF-S, and my Nikkor 24-70 f/2.8 E VR (at 70mm). For the Sigma Sport, I tried both the “standard” and “high speed” focus algorithms. Surprisingly, they seemed to perform the same at any given light level. My Sigma 150-600 is about 20% faster using its “high speed” algorithm. I measure focus speed via how long it takes to change focus from minimum distance to infinity. For the Sigma 70-200, that means the range is a bit less than 4 feet to infinity. I use the back-button (AF-ON) focus technique while in continuous auto-focus mode and phase-detect focus. As I explained in a previous article, I use my D850 video at 120 fps to film the focus distance scale on the lens. Using this technique, I get a resolution of 0.0083 seconds per frame (120fps) to time the focus action. The f-stop used in testing doesn’t matter, because the camera always focuses with the aperture wide open. I measure light levels by looking at the EXIF data from the photograph, which I get using the “Exiftool” program. This program is free, and invaluable for retrieving a wealth of information about each photo. I had intended to graph my measurement data, until I looked at the numbers. There was almost no change in how long it took to focus, up to the point of failure. In dim light, focus just got unreliable instead of slow. In really poor light, the camera would eventually go through the whole focus range a couple of times and then give up. Graphing this kind of timing behavior would be an exercise in futility. Light Levels I did all of my testing outdoors. After sunshine testing, I waited until sunset. I would take a new shot about every 5 minutes until near-darkness. I did the testing outdoors so that I could focus on a target that was about 200 yards away. For my “bright” light testing, I’m using sun-lit shots in the later afternoon. This isn’t the brightest light you can get, but light levels beyond this don’t provide any improved focus speed. The EV (exposure value) corresponding to this light is around 14.3. I tried light levels all the way down to EV 1.3, which is near-darkness. The only lens to (occasionally) succeed at this level was the Nikkor 24-70 f/2.8, and it started getting unreliable at EV 3.6. Tests that didn’t succeed are marked with a “---“. Focus Time (Seconds) Versus EV Results EV 70-200mm 85mm 24-70mm Notes 14.3 0.358 0.458 0.25 Bright Light 13.4 0.358 0.458 0.25 9.9 0.358 0.458 0.25 9.3 0.358 0.458 0.25 8.9 0.358 0.517 0.25 8.5 0.358 0.558 0.25 8.3 0.358 0.567 0.258 7.9 0.358 0.567 0.258 7.3 0.358 0.567 0.258 6.6 0.358 0.567 0.258 6.3 0.358 --- 0.267 85mm too slow now 5.6 0.367 --- 0.267 4.6 0.367 --- 0.267 3.6 0.383 --- 0.283 50% fail Sigma & 24-70 2.6 --- --- 0.909 70% fail 24-70 1.3 --- --- 0.909 80% fail 24-70 Conclusions I was very surprised by these test results. I remember reading many years ago about cameras/lenses that would demonstrate a smooth exponential decrease in focus speed at decreasing light levels. Lower light levels always meant slower focus. I imagine that old camera technology (and very slow on-board computers) forced this type of behavior. Fast-reacting modern cameras can largely bypass this problem, and they remain very responsive in most levels of illumination. The testing I did (both the D500 and D850) had very little change in focus speed up to the point that they would suddenly become unreliable at focusing. In very low light, the focusing would typically go through the whole focus range twice (near-far-near-far) and then quit. Sometimes final focus was okay, but mostly it would fail. The Nikkor 85mm f/1.4 would get “near” to the correct focus distance, and then really slow down just before achieving final focus (in low light levels). I consider this a “fail”, since it would take about 2 seconds to finish focusing. This lens has always been notorious for being slow to focus (most f/1.4 lenses are). I also noticed that my D850 video (used to capture the lens focus scale action) showed how pathetic its contrast-detect focus was in dim light. It would end up hunting back-and-forth, rarely locking on the target. I totally understand why cinematographers stick with manual focus. Each lens/camera combination you own probably has its own focus behavior fingerprint. Knowing how your gear behaves before you go shoot something important might just save the day. There’s a reason why lenses have that manual focus ring on them.

This isn’t something that I’d recommend doing, but I know that there are many people interested in putting Sigma’s TC-1401 1.4X teleconverter onto the Sigma 150-600. Sigma has even sold this combination as a kit. So here goes. Sigma TC-1401 1.4X teleconverter on Nikon D850 The field of view at 840mm is outrageously narrow. On a DX camera, at a 1260mm equivalent, it’s even outrageous-er. I know that isn’t a word, at least not until you try this combination. The Sigma 150-600 Contemporary is a good lens, but at 600mm it’s pretty much at the limit of its abilities for quality resolution. Adding a teleconverter into the mix certainly isn’t going to help. The camera focus system isn’t going to be thanking you, either. A 2X teleconverter would be out of the question on this lens, both for resolution quality and the ability to auto-focus. I would be remiss if I didn’t remind the audience that you have to attach your Sigma teleconverter to the lens prior to mounting it to the camera. If you don’t follow this procedure, then it won’t autofocus. Resolution tests I performed a resolution test with the lens/teleconverter combination at 840mm and f/9.0, which is with the aperture wide open. This means that the lens was zoomed to its maximum 600mm marking, getting a combined focal length of 840mm. The aperture of f/9.0 is about as dim as I’m willing to photograph moving subjects. Quality will of course improve some when you stop down the aperture. I figured that there isn’t much sense in testing this teleconverter at small focal lengths, since it would be much wiser to merely remove the teleconverter. If somebody bothers to put a teleconverter onto a lens that already zooms to 600mm, it means they want as much reach as they can get. I photographed a resolution test chart from 62 feet (!) or 18.84 meters. Even from this far away, only a piece of the test chart could fit into the field of view. This is as far away as I am able to get from the target where I do my testing. Even at this distance, I begin to wonder if air turbulence starts to become a factor. I perform resolution tests using “live view” with contrast-detect focus, to eliminate focus calibration from being an issue. I set my camera up to use electronic front-curtain exposure to rid vibrations. I also use a wired remote release. Even contrast-detect focus gives variable results, so I pick my sharpest result (from 10 shots) to report. 840 mm resolution chart detail, Sigma TC-1401 f/9.0 on Nikon D850 The 840 mm peak resolution was measured to be an MTF50 of 32.4 lp/mm. This is an equivalent of 1549 lines per picture height. A common minimum “quality” resolution benchmark is an MTF50 of 30 lp/mm. This result just made it into the “good” category. Note that the exif photo data reported above shows 850mm. You may notice that the other resolution measurements in the shot are less than the 32.4 lp/mm reading. Lens resolution is a lot more complicated than a single number. Generally, these resolution results aren’t too good and fall a bit below what I consider acceptable. The shot above is un-sharpened raw format, and any chromatic aberration would show clearly. You can see a trace amount of it here, although post-processing would easily remove it. There is just about zero vignetting with this combination, as you'd expect. 600 mm f/6.3 resolution chart center, Nikon D850, no teleconverter 600 mm f/6.3 resolution chart edge, Nikon D850, no teleconverter Next, I removed the teleconverter to repeat the test for comparison purposes. Everything else remained the same as the shots that I had taken with the teleconverter attached. The MTF50 peak was measured at 48.0 lp/mm. The equivalent peak resolution here is 2294 lines per picture height. The shot quality looks significantly improved, as expected. The resolution change is 1549/2294, or 0.68, which means a drop of 32 percent by adding the teleconverter to the lens. This is a better result than just cropping the shot, but not by a very significant margin. Focus Speed The cameras I tried (Nikon D850 and D500) struggle to focus with this setup when not in good lighting, but incredibly they can still focus in moderate shade. No birds in flight with this kind of rig, though, unless they’re the big heavy birds. For lesser cameras, focus performance is going to go downhill in a hurry. I measured focus speed with and without the teleconverter to compare the differences. My usual testing involves setting the lens on its minimum focus distance to find how long it takes to focus on infinity. I do these tests in sunlight, so that I can compare various lenses and cameras in good lighting conditions. My tests were at 600mm (or 840mm with the attached teleconverter). I used my D850 on some tests, and the D500 on others. I didn’t notice any focus speed differences between these two cameras. They’re advertised to focus down to f/8 (not all focus points, though). The aperture f/9 didn’t generally pose in a problem in the conditions I use this lens, despite being “out of specification” for the camera focus system capability. If your camera doesn’t have any f/8 focus points, then don’t even consider using this teleconverter. Also, you can notice focus inconsistencies if you pick any non-f/8 focus sensors (try to stick with the center focus point). Without a teleconverter attached, it takes 0.633 seconds to focus through the full range. With a teleconverter, it takes 1.183 seconds to focus through the same range. This is the worst performance I have witnessed from a lens to date. Next, I tried a more “real-world” big lens focus test, going from 50 feet to infinity. I experience conditions like this all the time out in the field. Keep in mind that 50 feet is actually pretty "close" at this extreme magnification. Without the teleconverter attached, it takes 0.125 seconds to focus through this range. With the teleconverter, it takes 0.2917 seconds to focus through this same range. This result is perfectly acceptable in most shooting conditions. Generally, it takes about twice as long to focus when using the teleconverter. For realistic focus distance changes, this is totally acceptable and better than I would have thought. You’re crazy if you routinely focus from minimum distance to infinity out in the field. Conclusion I don’t personally think that adding the teleconverter is worth it for this lens. I’d just as soon crop a shot and get only marginally worse results than using the teleconverter. Stop down the aperture, if your subject isn't moving, for a moderate increase in resolution. I am a real fan of using the Sigma TC-1401 on my 70-200 f/2.8 Sigma Sport, but I just can’t recommend using it on the Sigma 150-600 Contemporary lens.

This article will show you how to make, preserve, and verify an accurate white balance preset. If you have a particular lighting setup that you use frequently, then you should save its white balance calibration to be able to return to it later. Even if you use Raw format and have a photo-editing program that lets you adjust the white balance after the fact, you’ll thank yourself for getting things right before you take the shot. Also, the “Auto” white balance feature of your camera isn’t quite as smart as you might think with non-standard lighting or subjects. If you’re doing a product shot for a client, they probably won’t remain your client for long if the color in the shots isn’t perfect. As an example, there used to be a term “Kodak Yellow”. If Kodak’s packaging wasn’t reproduced perfectly in photographs (or a magazine page), it would be quickly rejected. (Remember them?) To create a perfect white balance, you’ll need a grey card. Your goal is to get shot histograms that have the R,G,B peaks that exactly match each other. To achieve this color perfection, you need to calibrate against a subject that is entirely neutral, like a grey card. I’m going to show you an example using my LED ring light. Under “average” conditions, the color balance is fairly close when using “auto” white balance, but when I am doing macro shots of things like the inside of a flower, the color balance can get awful. This earlier article discusses how “auto” white balance can go terribly wrong. My example procedures will demonstrate two cameras: the Nikon D610 and the D850. You might think that the procedures would be identical, but remember we’re talking about Nikon here. They’re generally loath to do the same thing twice. I give my white balance presets meaningful names, such as “LEDring” because I’d never be able to remember them otherwise. Please note that there are some light sources that you cannot successfully calibrate against. An example of this would be sodium vapor street lights, which don’t contain enough of the full light spectrum. D610 White Balance Preset Procedure Histogram of a proper white balance The shot above shows the D610 capture of a grey card using a white balance preset. The preset used here was the “d-2”. The D610 accepts up to 4 presets. The histogram peaks show that the capture was completely neutral, since the R,G,B peaks align perfectly. I used an LED light source, and the “d-2” preset was calibrated to this light. The procedures that follow show you how to achieve this precise calibration. Note that a non-neutral subject photo can’t be used to verify proper white balance, since the R,G,B histogram feedback won’t show the vertical alignment of color peaks. Capture Your Preset Set up your light to illuminate a grey card Press the WB button (has the ‘?’ on the button) Spin the “main” (rear) dial to get “PRE” on the control panel Spin the “sub-command” (front) dial to choose d-1 through d-4 Release and re-press (hold down) the WB button to get “PRE” to blink Fill the frame with the grey card (it doesn’t have to be in focus) Press the shutter (within 6 seconds, before PRE stops blinking) You should see “Good” on the control panel, if it’s successful You will see “no Gd” if the measurement fails Name Your Preset Go to the “Shooting” menu (the camera icon) Select the White Balance option Press the selector right-arrow Select PRE Preset manual Press the selector right-arrow Choose the preset you used in the capture step, e.g. “d-2” Press the ISO (the “-“ magnifier) button to select the preset You’ll note the preset already shows “d-2:LEDring”, because the preset already had a name. This procedure will let you alter any pre-existing preset name. If you inspect both the “d-1” and “d-2” presets above, you’ll see that they have a little “key” icon at their top-right corner. This key indicates that the preset is protected and can’t be accidentally deleted. The steps that follow assume that the “d-2” preset isn’t protected. Also note that the d-3 and d-4 presets above haven't been assigned anything yet. If they were assigned, a little picture would show behind them. Select “Edit comment” and press the selector right-arrow Edit the comment text using the arrows and the Ok button If you type an incorrect letter, press the “trash can” button Press the Qual (the “+” magnifier) button to save the name Protect Your Preset Select the White Balance | PRE Preset Manual option Press the selector right-arrow Select “Protect” and press the selector right-arrow Note that the screen above shows “Protect OFF”; if it instead it showed “Protect ON”, then you’d know it was already protected. Select “On” Press the “Ok” button to finish The preset selection screen will now have the little “key” icon on the protected preset and you can’t delete it. If you change your mind, then repeat this procedure but select the Protect “Off” choice. Use Your D610 Preset Press the WB button (has the ‘?’ on the button) Spin the “main” (rear) dial to get “PRE” on the control panel Spin the “sub-command” (front) dial to choose d-1 through d-4 D850 White Balance Preset Procedure Histogram of a proper white balance The shot above shows the D850 capture of a grey card using a white balance preset. The preset used here was the “d-2”. The D850 accepts up to 8 presets. The histogram peaks show that the capture was completely neutral, since the R,G,B peaks demonstrate perfect vertical alignment. I used the same LED light source as before, and the “d-2” preset was calibrated to this light. The procedures that follow show you how to achieve this calibration. Capture Your Preset Set up your light to illuminate a grey card Press the WB button on the top left dial (on top of the camera) Spin the “main” (rear) dial to select PRE Spin the “sub-command” (front) to select the “d-1” through “d-8” Release and re-press (hold down) the WB button to get “PRE” to blink Fill the frame with the grey card (it doesn’t have to be in focus) Press the shutter (within 6 seconds, before PRE stops blinking) You should see “Good” on the control panel, if it’s successful You will see “no Gd” if the measurement fails Name Your Preset Go to the “Photo Shooting” menu (the camera icon) Select the “White Balance” menu Press the right-arrow on the selector Select “PRE Preset manual” and press the 'right' multiselector arrow. Select the “d-2” (used in the capture of the LED light) Press the “Ok” button (Note that I had already given this preset a name, which shows when I selected the “d-2” preset). If you inspect the “d-1” preset above, you’ll see that it has a little “key” icon at its top-right corner. This key indicates that the preset is protected and can’t be accidentally deleted. The “d-2” preset doesn’t have this key showing, so it’s not protected. Also note that the d-3 through d-8 presets above haven't been assigned anything yet. If they were assigned, a little picture would show behind them. Select the “Edit comment” Press the right-arrow on the selector You’ll note that the screen already displays “d-2: LEDring” since I had already given this preset a name. This procedure lets you change the name of the preset, if you wish. Use the touch screen to type in the name of the preset Use the trash can button to fix mistakes You use the same procedure to modify the preset name Press the “Ok” button to save the name Protect Your Preset Select the White Balance | PRE Preset Manual option Press the selector right-arrow Select the “d-2” (used in the capture of the LED light) Press the “Ok” button Select the “Protect” option Press the selector right-arrow Note in the shot above that the “d-2” preset isn’t yet protected (it says “OFF”. If it instead indicates “ON”, then you know it’s already protected. Select “On” Press the “Ok” button to finish Use Your D850 Preset Press the WB button on the top left dial (on top of the camera) Spin the “main” (rear) dial to select PRE Spin the “sub-command” (front) to select the “d-1” through “d-8” Conclusion For the occasions where you have a lighting setup that you use regularly, such as a studio, you really should use a calibrated white balance. You don’t want to rely on “auto” white balance, in case your camera sees an unusual scene and makes a poor color decision. Professional wedding photographers will often scout a venue before the event and save the measured white balance(s) from different rooms. Smart photographers will also tack on a name to these white balances, to minimize mistakes during the shoot. If you consistently use flash instead of ambient lighting, then your preset for the room will probably get overpowered by the flash. If you intend to use a preset white balance long-term, then it makes good sense to both name and protect that preset against accidental erasure. Not only will the photo colors be consistently more accurate, but you’ll save a ton of time when you edit your shots.

If you want to explore the world beyond life-size, the Nikon PB-4 bellows is a terrific vehicle to get there. This 70s-era bellows is the best one that Nikon ever made, and you can still find it for sale (used) on sites like eBay. Back in the day, you’d probably have purchased the Micro-Nikkor 55mm f/3.5 lens to use with this bellows. Nikon also sold a 105mm f/4 P lens that you could actually focus to infinity on the bellows! This 105mm lens would allow up to 1.3X magnification forward-mounted on the PB-4. The 105mm gives a better working distance than shorter lenses. This lens is essentially useless without the PB-4 bellows, since it can’t focus by itself. It’s worth noting that the PB-4 bellows has both swing and shift controls. These controls were mainly intended for use with the Nikkor 105mm f/4 P lens. This lens has a large image circle, and in combination with the PB-4 enables you to have the same kind of controls as a “view camera” for manipulating the plane of focus and perspective control. As you’ll see, though, these controls can be useful for any lens attached to the PB-4. As you will note below, there’s a lot of hardware and software involved in quality close-up photography. I hope that this guide gives you a better idea of what gear you will probably want to use. Bellows PB-4 with Micro-Nikkor 60mm f/2.8 AF-D Today, a really good choice for a lens on the PB-4 is the Micro-Nikkor 60mm f/2.8 AF-D, which you can still buy. It’s one of the only lenses you can still obtain new (as of this writing) that has an aperture ring. When you mount a lens on the PB-4, you won’t have any electrical contacts to control an aperture, so you need a lens with a mechanical aperture ring. The Micro-Nikkor 60mm lens works for FX format, which is helpful for its larger image circle. By itself, this 60mm lens will autofocus down to 1X (lifesize) magnification; the PB-4 is for going beyond this magnification. Here’s a rare occasion where you will want to unlock the lens aperture ring, so that you no longer keep it locked at f/32. You will need to alternate apertures between wide-open (to focus) and the shooting aperture. Manually rotate the aperture ring, instead of letting the camera operate the aperture. Please remember to lock the lens back at f/32 before using it for regular photography on your camera without the bellows, or you’ll get the “f EE” error. BR2, BR3, and Step-down rings on 60mm lens For optimal sharpness beyond life-size magnification, most lenses work better when you mount them in reverse. Nikon used to sell a ring called the “BR2”. With this ring, you’d screw it into the lens filter threads and then mount the lens backwards. Unfortunately, the older Micro-Nikkor lenses had 52mm threads; the 60mm Micro-Nikkor has 62mm threads. To mount the BR2 ring onto the 60mm Micro-Nikkor, you need “step-down” rings that go from 62mm to 52mm. You can still buy a new Nikon “BR2A” ring today that does the same thing. Step-down ring sets (and step-up ring sets) are cheap and well worth the investment. To protect the rear of your lens, now that it’s mounted in reverse, Nikon still sells a ring called the “BR-3”. This ring mounts on the back of the lens, and it has a 52mm thread that you can mount a protective filter onto. The BR-3 ring by itself acts like a lens shade. If you have a larger filter you’d like to use, then you can use “step up” rings for these. To mount a modern Nikon camera on the PB-4, the bellows camera mount must be rotated into the vertical (portrait) orientation. After mounting the camera, you can then rotate the camera back into horizontal (landscape) orientation. Note that some camera models have a built-in flash that can slightly rub on the bellows while mounting the camera. The Nikon D610 is an example of such a camera; it still can be mounted, however. Also note that any camera battery grip must be removed before the camera will successfully fit onto the bellows. Models such as the D5 won’t work on this bellows. My Nikon D850 camera fits onto the PB-4 just fine, as long as I remove its battery grip attachment first. It would be possible to use an extension tube on the rear of the bellows to gain enough clearance for cameras to fit onto the bellows. I still don’t think that cameras with grips could clear the rack-and-pinion rails, though. Once the camera is mounted, you can adjust the front (lens mount) and rear (camera mount) independently on the PB-4 rack-and-pinion focus rails. This is how you control the magnification you wish to use. There’s a handy millimeter-marked scale on the side of the focus rail. Swing and Shift Bellows Capabilities Nikon currently sells “PC” lenses, which stands for perspective control. These lenses, however, are only for conventional focus distances and low magnification. The PB-4 bellows, created in 1970, has perspective control built in. This bellows essentially takes over where the PC lenses leave off, to enable perspective and focus-plane control at high magnification and close distances. Swing (rotate) adjustment To change the plane of focus, you can alter the lens swing adjustment up to 25 degrees in either direction about the vertical axis. There’s a friction lever just under the mounted lens at the front of the PB-4 to enable this adjustment. Shift adjustment To shift the center of the subject, you can shift the lens on the bellows up to 10mm either left or right. There’s a separate friction lever at the front of the PB-4 to enable the shift adjustment; it’s near the ‘swing’ adjustment lever. It’s also possible (and usually necessary) to combine both swing and shift at the same time. See the Scheimpflug principle down below; it shows you how to successfully use these controls. You typically use these controls when the (flat) face of a subject doesn’t align with the flat face of the camera sensor. You need to swing the lens until its optical center plane (parallel to the lens diaphragm) intersects both the sensor plane and subject plane. Next, you typically need to shift the lens to center your subject in the viewfinder. Don't worry, I'll explain this procedure a little better in a minute. The bellows only lets you make a swing adjustment about a vertical axis. The shift adjustment is only available along a single axis, as well. Setup to photograph a rotated coin, viewed from above The photo above shows the 60mm lens, the PB-4 bellows, and an LED ring light being used to photograph a coin held in front of the lens. The coin is rotated, so that its face is no longer parallel to the camera sensor. The swing and shift controls were used to get the entire face of the coin in focus. Both the BR2 and BR3 rings were used to reverse-mount the lens and provide an attachment surface for the ring light. This arrangement as shown above results in a 2.5X magnification. That Scheimpflug Dude No, that’s not a bad word. Austrian army Captain Theodor Scheimpflug was determined to get rid of perspective distortion in aerial photographs. Theodor was born in 1865 and got interested in photography in 1902. Theodor combined photography with kites and balloons to make better maps. He read about a British 1901 patent from a French guy named Jules Carpentier. Jules had figured out the solution. Modest as he was, Scheimpflug insisted on giving credit to Jules Carpentier for the details of how to accomplish this distortion removal. Through the vagaries of history, credit for this “principle” was given solely to Scheimpflug. When later questioned about the Scheimpflug Principle based upon his own patent, Jules said he didn’t mind that it was named after Scheimpflug, as long as his invention was found to be useful. Scheimpflug, who got several patents of his own in the realm of aerial photography and panorama cameras with up to 8 lenses, shared his technique freely. Nowadays, most architectural photographers are well-versed in his principle. They can get photos of the fronts of buildings that are dead sharp, even if they’re using a setup with a narrow depth of field. Lots of architectural photographers are now using those Nikon “PC” lenses. But I digress, as I often do. How do we use this PB-4 to get sharp photos of stuff that might not be perfectly aligned with the camera sensor? By using the Scheimpflug Principle, of course. Subject Plane, Optical Center Plane, and Sensor Plane For starters, focus on the middle of your subject without any shift or swing adjustments. To get your rotated subject plane in focus, swing the lens until the red “subject plane”, the orange camera “sensor plane”, and the green “optical center plane” all intersect. In the sample above, the three planes all converge at a spot about 1 meter to the left of the camera (slightly out of the frame). You’re rotating the green plane (the lens), and leaving the other planes alone to achieve this intersection. After the subject plane is in proper focus, you probably need to shift the lens to get your subject centered in the viewfinder. Since the shift movement doesn’t change the direction of the optical center (green line), the subject doesn’t go out of focus while shifting the lens. Scheimpflug Principle In a nutshell, that’s the “Scheimpflug Principle”. Scheimpflug was a smart guy, as was Jules Carpentier. You should thank the both of them. This stuff is a bit complicated, until you go through the alignment exercise yourself a couple of times. It’s a lot simpler to just keep your subject plane parallel to the camera sensor, but where’s the fun in that? Closeup results from setup shown above. Coin face is entirely in focus. The photos above show a coin mounted with a significant rotation, relative to the camera sensor plane. Normally, it would be impossible at these magnifications to get the rotated coin face in focus even when the lens aperture is stopped down. The swing adjustment, combined with the shift adjustment, made getting everything in focus possible with a single photo. It would also be possible to get everything in focus by stacking several photos, where focus is shifted slightly between shots (see discussion below). In the coin detail shot above, the reverse-mounted 60mm Micro Nikkor was stopped down to f/8.0, which gives a pretty shallow depth of focus. Thanks to the swing and shift controls on the PB-4, the coin face is entirely in focus. I didn’t have to stop down to a small aperture, which would have caused resolution-killing diffraction. The vertical field of view here is 9.75mm, or 2.46X magnification. I hope you can tell that this lens yields very, very sharp results. You can get a pretty good idea of the distance to the subject from the lens when using the BR3 ring while mounting the 60mm lens in reverse (using the BR2 ring and step-down rings) by inspecting the overhead gear setup shots included above. The clearance between the light and the subject isn’t huge (about 2 inches), but it’s sufficient to get very good illumination. The whole coin (NOT using the bellows) The coin used in these examples is 39.1mm in diameter. The face itself is 0.55mm offset from the featureless coin surface. This is roughly as close as most people ever get when they use a macro lens by itself. The PB-4 takes you to a whole new level. Since the invention of focus stacking, it’s now possible to get a huge depth of focus via multiple photos (see below). The stacking invention makes Scheimpflug no longer an imperative (unless you use film). It’s still quite nice to get the job done with a single photo, versus combining dozens of shots to get there. Lighting Hardware Example LED ring light mounted onto BR-3 ring It’s often preferable to use a continuous-light source to illuminate small subjects, compared to using a flash. The BR-3 ring works as a nice surface to attach ring lights. There is still enough working range to your subject if you choose a small light. My ring light is about 34mm thick. I like LED lights, because other types of continuous lights tend to cook your subject. Without continuous lighting, the (non-sunlit) subject is usually too dim to focus easily. The light shown above has three tightening screws that grab onto the BR-3 ring. Remote release Infrared remote and 10-pin wired remote Depending upon your camera model, I’d recommend that you use either the cheap ML-L3 infrared release or a 10-pin wired remote to minimize vibrations. Don’t forget to use the electronic front-curtain shutter mode if your camera has it, to really rid vibrations. Working Distance Example subject held in front of lens The shot above shows a diamond ring that is in focus at a medium bellows extension. This should give you a good idea about how much working distance you have between your gear and the subject. There isn't a single "working distance" when discussing a certain lens on a bellows. The higher the magnification, the shorter the working distance. I made a little device that uses an alligator clip to hold small objects. The device fits into the end of the bellows and has the necessary degrees of freedom to raise, shift, and rotate small objects. I don’t know if you can buy any gizmos that will fit into the PB-4 bellows “slide copier” attachment hole for holding stuff. I was forced to make my own; I got tired of having to get my rig close to table tops with tripod legs always in the way. The bottom control knob on the bellows is essentially used to balance all of your gear over the tripod. This collection of hardware can get heavy, so you’ll want to place it at the point of balance after setting the bellows extension. Stacking Software The depth of focus at high magnification isn’t much thicker than a sheet of paper. I recommend that you explore the world of focus-stacking, where you can combine many shots into a single photo. Each shot’s focus is slightly shifted, and the focus-stacking software combines them. The PB-4 bellows is ideal for letting you shift the camera/lens combination on its rack by small amounts between shots to have fine control over the focus shifting. You twist the bottom PB-4 knob to shift the whole camera/lens/light combination without changing magnification. I have an article here where I discuss focus-stacking. The article shows how to use this free software; there are several programs (not free) that accomplish the same task. It generally takes 50 to 70 shots to get enough depth of focus in the final stacked photo. The magnification, lens, and subject will determine how many shots you will need. One downside to photo-stacking is that you will need to crop the final stacked photo, because the edges are ‘fuzzy’. It’s almost as if an ‘FX’ photo ends up being a ‘DX’ photo. Try to allow for a liberal border around your subject by shooting at a lesser magnification. Stacked photo result using CombineZM I used 50 shots to make the finished photo of this wasp. I should have used a few more shots to get the tip of the leaf in full focus. There's about 15mm of focus depth here; without focus stacking, either the leaf or the wasp's eye would be in focus, but not both. I used my LED ring light for illumination. Conclusion I bet you didn’t think using the PB-4 bellows could be this complicated, did you? Close-up photography can get quite involved; think of it as a journey, and not just an end result. There’s a largely unseen world out there, even in your own back yard. Make it visible.

If you’re interested in making your videos look a bit more professional, here’s some hardware to consider. A camera stabilizer gives you the ability to walk and maintain fluid motion with your video. Unlike “steadicams” with active gyro stabilizers, this inexpensive Roxant Stabilizer Pro is purely mechanical. The smoothing effect relies upon your camera being perfectly balanced on top of a ball-and-socket joint. The stabilizer hardware acts like a long pendulum that slowly swings as you move your camera, continually restoring a level view and counteracting your motion. The Roxant has lots of adjustability to accommodate a wide range of camera hardware. That said, a successful setup requires very precise balancing in both front-to-back and left-to-right. Before you try balancing your rig, you’ll need to do some thinking ahead. First, you’ll want to remove your camera strap and lens cap. Believe it or not, even the weight difference between adding/removing a memory card will affect the balance. If you intend to use a filter, then attach it. Set your zoom lens on the desired focal length, too. If you want to also attach an external microphone atop the camera, make sure you also attach it prior to working on any balance adjustments. My Roxant unit arrived with a slightly “sticky” ball-and-socket joint (on top of its handle). I added a small drop of high-quality synthetic oil lubricant (don’t use grease!) to the joint. You want this joint as frictionless as you can get it. Roxant Stabilizer Pro and DSLR In the shot above, you’ll note that I assembled the silver bottom portion that holds the counter-weights as fully-extended as I could get it. There’s a good reason for this. A long pendulum will swing at a much slower frequency than a short pendulum; this is basic physics. The mass at the end of the pendulum doesn’t matter; the length of the pendulum is what defines how long the swinging motion takes. You want your video to look as smooth as possible while you walk, and the slow-reacting pendulum will achieve this. You want the bottom of your rig (where the counter-balance weights are) to be heavy enough that it always pivots to the lowest point of your setup while in use. You want front-back and left-right balance, but definitely NOT top-bottom balance. Camera attachment slot and handle attachment view In the view above, you can see the long slot (with 3 short cross-slots) for attaching your camera. Lighter cameras such as this Nikon D5300 will typically get mounted toward the rear of the main slot (farthest from the handle attachment pivot point). I avoid using the little cross-slots for left-right balancing, because it’s too hard to get precise adjustments using these cross-slots. Use of these cross-slots also forces you to lose the ability to fine-tune the front-rear balance (via the main slot). I discuss below how to get the proper left-right balance. There are five holes available for attaching the handle. The attachment locations of the camera and the handle interact with each other, which can be either a blessing or a curse. Front view The front view shows a couple things of note. First, notice that the silver bottom bar is misaligned with the black upper bar. This misalignment causes the unit to rotate counter-clockwise, as viewed from the rear of the camera. This is how I got the left side of the camera to move lower and become level left-to-right (also from the point of view of the rear of the camera). The left-right levelling adjustment is very simple to make, and you might want to save this step for last. The front-back adjustment (discussed next) should probably be done first (after mounting the camera and the Roxant handle). The other thing to note above is a pair of stainless-steel bearings (not included in the kit) that I added to one of the standard black counter-weights at the bottom of the unit. Using combinations of the included three weights in the kit, I wasn't able to get the unit perfectly level front-to-back. These bearings were just the right weight to achieve perfect front-rear balance, when combined with the heaviest included counter-balance weight. Washers would have worked for finer counter-balance control, too. You may not need any extra weights to get front-back balance, but just be aware that it’s an easy addition that might save you some frustration. You can also raise/lower the silver part of the vertical counter-balance to affect front/rear balance, but I’d suggest you keep the length near the maximum for the best stabilizing effect. I found that sliding the camera in its mounting slot was too crude to achieve good balance. My goal with this rig was to place each adjustment at an end of its slot. This way, the pieces can be taken apart and reassembled without having to mess with another re-balancing effort. Holding the Roxant stabilizer The photo above shows the unit after it has been balanced. Everything pivots around the little ball-and-socket joint at the top of the handle. There is a lock provided near the top of the handle, if you want to stop the stabilizing effect. The whole kit (plus my extra counter-weights) Final Thoughts It took me a couple of hours of frustration to get my setup perfectly balanced. The quality of the video you can obtain is worth the effort to get this rig properly leveled. Videos made purely from atop a tripod can get boring. Video captured while walking around without stabilization can make your audience nauseous. This Roxant stabilizer doesn’t absolve you from using careful technique; it merely makes it easier to get full-motion video without the substantial expense of a full-blown steadicam. It’s also nice to finally have something that doesn’t need batteries and chargers. If you don't feel that you're up to the challenge of fine-tuning these positioning adjustments to balance your setup, then I wouldn't recommend you buy this hardware. Also bear in mind that changing lenses, etc. will result in the need for a new rebalancing effort. I hope you will find this discussion useful for avoiding some of the pitfalls I had to endure to get up and running. Happy shooting.

Adobe no longer keeps the Lightroom standalone version updates on their web server. Face it; Adobe has abandoned its standalone users. If you want to install Lightroom6 from your DVD onto your new computer, you’ll only get Lightroom 6.0. If you have a second computer that already has Lightroom installed with the updates (e.g. version 6.14), you’re in luck! If you have never done any updates, then I’m sorry to say that you have little hope of getting your standalone Lightroom program updated. The CreativeCloud Lightroom users continue to get regular updates, and this procedure doesn’t apply to them. Personally, I’m not a software-rental kind of guy and I want to stick with the standalone Lightroom instead. Follow the instructions below to get your target machine updated to version 6.14 (or whatever is your latest update). You’re allowed a maximum of two Lightroom installations when you buy the standalone Lightroom on DVD. These instructions are for the Windows 10.0 x64 operating system. I don't know if a similar procedure will work for other operating systems. 1) If you already have a separate second Lightroom installation, but you want to shift it onto another (third) computer instead, then select ‘Help | Sign Out’ on that other computer from inside Lightroom. Now, you will be able to install and use Lightroom on another computer. The “signed-out” computer will no longer permit you to use Lightroom on it, but it won’t cause Lightroom to be un-installed there, either. 2) Install Lightroom 6.0 from your DVD onto your (new) target machine. 3) Verify your new 6.0 installation works (enter your Lightroom DVD serial number, etc.). 4) Copy “C:\Program Files\Adobe\Adobe Lightroom\*.*” onto a USB stick mounted on your Lightroom 6.14 machine (it’s about 1.8 GB in size). You could substitute writing a blank DVD with these folders if you don’t have a USB stick. 5) Put the USB stick into your target Lightroom 6.0 machine. 6) Copy the folder “Adobe Lightroom” over your target machine “C:\Program Files\Adobe\Adobe Lightroom” folder, in order to replace the (6.0) files and add any new (version 6.14) files. 7) Allow “Administrator Permission” if requested, to allow all identical filenames to overwrite the files on your target machine. The files copied here won’t affect your Lightroom catalog, which is stored in: C:\This PC\Pictures\Lightroom\LightroomCatalog.lrcat That’s it! Now, your new computer’s 6.0 Lightroom installation should have all of the necessary files to transform it into a Lightroom 6.14 installation!

Now that Adobe has stopped providing updates to standalone Lightroom, you can’t get lens profile updates any more. Here’s a way to sidestep that problem when you get a new lens. Lens profiles, by the way, let you correct for vignetting, lens distortions like barrel or pincushion, and chromatic aberration. If you aren’t using this feature for your Raw files in Lightroom, you should be. For an extreme example of how useful a lens profile can be, you should read this article Lightroom has this new lens profile available, courtesy of the DNG Converter The very same lens profile files that you used to get with Lightroom updates are provided with their still-supported free program called “Adobe DNG Converter”. You can get updates to the DNG Converter program from the Adobe site, at least as of this writing. The latest version of this program (for Windows 10) is in a file named “DNGConverter_12_2.exe”. After installation, a great many lens profiles are installed onto your computer. You also get a special folder created that you’ll need to add files into later. If you didn’t know, the “DNG” stands for “digital negative” and is Adobe’s attempt to create a generic raw-format file. The format didn’t catch on with the camera industry as well as Adobe had hoped, and today it has limited usefulness. The lens profile file names have a suffix of “.lcp”. I got a new Nikon-mount “Sigma 14-24 f/2.8 Art” lens, for instance, that Adobe supports in their DNG Converter under the file name: “NIKON CORPORATION (SIGMA 14-24mm F2.8 DG HSM A018) – RAW.lcp”. This new lens isn’t supported in my Lightroom 6.14 version, which would normally mean that I could only do “manual” lens profile corrections in Lightroom. The manual lens corrections are really second-rate compared to the Adobe-supplied profiles. After installing the DNG Converter program, the Nikon-mount Sigma lenses can be found in the folder (in Windows 10 x64) under: “C:\ProgramData\Adobe\CameraRaw\LensProfiles\1.0\Sigma\Nikon\”. There are 86 lens profiles just in this one folder alone. It's possible that you will have trouble finding folders in Windows if they're hidden. You'll need to tell Windows File Explorer to enable display of hidden folders. To use this lens profile in Lightroom, I just copied the .lcp file from the Camera Raw location to my “Downloaded” folder called: “C:\Users\Ed\AppData\Roaming\Adobe\CameraRaw\LensProfiles\1.0\Downloaded”. The path shown above has the “user name” of “Ed” for my machine; I assume yours is different. A new lens profile should be copied here for Lightroom to find it After copying the .lcp file(s) into the “Downloaded” folder, you should be able to start up Lightroom and have the new lens profile(s) available. Be aware that this “Downloaded” folder won’t exist if you don’t install the DNG Converter program. Conclusion You may not be able to get any new program updates for the standalone version of Lightroom from Adobe any more, but at least this trick will let you update your lens profiles. Let’s hope Adobe will keep updating and offering its DNG Converter program. Another problem related to the loss of updates is the fact that Adobe will no longer let you download any standalone Lightroom updates beyond version 6.0. If you try installing Lightroom from your DVD (version 6.0) onto a new computer, you’re stuck with version 6.0. I’ll be addressing a fix to this problem in a future article, so stay tuned.

Here I go again. I intend to question authority. This time, I’m going to perform some tests to see just how superior contrast-detect autofocus is at nailing focus, compared to phase-detect. We all know how slow contrast-detect focus is, but the results are totally worth it, right? I have been picking on my nifty-fifty (Nikkor 50mm f/1.8 AF-D) lens lately, and this round of testing maintains that same theme. I did all of these tests using my Nikon D850. Everybody claims that the AF-S focus technology is faster and more accurate than AF-D focus (AF-D requires an in-camera focus motor). If my 50mm AF-D lens can perform okay, then the AF-S lenses (with in-lens focus motors) should perform even better. Cameras designs are always getting better over time, and it may be that “rules” of the past aren’t necessarily true today. Modern sensors that contain “phase-detect” pixels muddy the water even more, since they can eliminate the slowpoke on-sensor focus issue. For each of the following tests, I shot at least 10 pictures at each aperture and focus mode. I am interested in maximums, averages, and ranges of results here. Resolution results are the best indicator of successful focus, so I’m doing an MTF50 resolution analysis as an equivalent to focus analysis. First, calibrate your lens properly It bears mentioning that it’s crucial that you accurately focus-calibrate your lenses; if you don’t, then you might just as well stick with contrast-based focus. Or buy a mirrorless camera (except they don’t work with AF-D lenses!). Get over the idea that lenses are calibrated well enough at the factory. They're not. Out of all of my cameras and lenses, I have only ever had two lens/camera combinations that were factory-calibrated properly. Focus-calibrate with a proper target The picture above shows the kind of target I use to calibrate (phase detect) autofocus. I got this target image from the same site that has the program MTFMapper. The target image tapers from left-to-right, such that perspective distortion makes the image look like both ends of the “trapezoids” appear as perfect rectangles when you rotate the target 45 degrees about the vertical. The web site has a few different images with different amounts of perspective in them. I print and mount different size images, depending upon the lens focal length and the distance to the target that will let me come close to filling the camera’s field of view. The picture shown has its left-hand side further from the camera than its right-hand side. This perspective effect isn’t perfect, and depends upon what lens focal length you’re testing. What is important is that you focus on the vertical edge depicted by the red rectangle as shown. This way, there is no confusion about what edge is used for focus. I always calibrate using these targets to get the best focus accuracy that I can. My MTFMapper program can show me the resolution of each edge in my test photos, so it's easy to see where the sharpest focus lands, versus where the camera tried to focus. Cameras and lenses have some degree of focus variation, which is why I performed multiple tests to get my data. If you have a lens that exhibits spherical aberration, then it will shift focus as you stop it down. This kind of lens problem can potentially defeat you with phase-detect focus (you can only have optimal focus calibration at one aperture). My nifty-fifty has “slight” spherical aberration, so it will be interesting to see if it affects the test results. Contrast-Detect Testing Contrast detect f/1.8 MTF50 resolution The f/1.8 results showed an average MTF50 resolution of 32.7, with a peak of 34 and a range of 2 lp/mm. Contrast detect f/2.0 MTF50 resolution The f/2.0 results showed an average MTF50 resolution of 34.7, with a peak of 35 and a range of 2 lp/mm. Contrast detect f/2.8 MTF50 resolution The f/2.8 results showed an average MTF50 resolution of 47.9, with a peak of 48 and a range of 1 lp/mm. Contrast detect f/4.0 MTF50 resolution The f/4.0 results showed an average MTF50 resolution of 58.9, with a peak of 60 and a range of 2 lp/mm. Contrast detect f/5.6 MTF50 resolution The f/5.6 results showed an average MTF50 resolution of 62.4, with a peak of 64 and a range of 6 lp/mm. Contrast detect f/8.0 MTF50 resolution The f/8.0 results showed an average MTF50 resolution of 59.1, with a peak of 60 and a range of 2 lp/mm. Phase-Detect Testing Phase detect f/1.8 MTF50 resolution The f/1.8 results showed an average MTF50 resolution of 33.5, with a peak of 34 and a range of 3 lp/mm. Phase detect f/2.0 MTF50 resolution The f/2.0 results showed an average MTF50 resolution of 34.7, with a peak of 35 and a range of 1 lp/mm. Phase detect f/2.8 MTF50 resolution The f/2.8 results showed an average MTF50 resolution of 51.1, with a peak of 52 and a range of 1 lp/mm. Phase detect f/4.0 MTF50 resolution The f/4.0 results showed an average MTF50 resolution of 55.3, with a peak of 56 and a range of 1 lp/mm. Phase detect f/5.6 MTF50 resolution The f/5.6 results showed an average MTF50 resolution of 62.3, with a peak of 63 and a range of 1 lp/mm. Phase detect f/8.0 MTF50 resolution The f/8.0 results showed an average MTF50 resolution of 59.0, with a peak of 59 and a range of 0 lp/mm. Summary of Results At the wide apertures, phase detect results are actually superior to contrast detect results. The lens was calibrated at f/1.8, and the lens exhibits a small amount of spherical aberration. It is expected that phase detect will work better at this calibrated aperture, and in fact it does. The repeatability of both focus systems (contrast and phase-detect) seems equivalent. At narrow apertures, the contrast-detect system gives slightly better results. I attribute the better results to the phase-detect system not being able to compensate for the focus shift from spherical aberration. If the lens were calibrated at a narrower aperture, phase-detect results would be better here (at the expense of wide apertures). What I’m not seeing is any overall superiority of contrast-detect focus. I’m not seeing any significant resolution bump and I’m not seeing any tighter focus range, either. As a matter of fact, the largest focus variation (large range value) was found with contrast-detect and not phase-detect! It would be wise to perform an analysis such as this on a lens-by-lens and camera-by-camera basis, but what I’ve seen so far has given me a dose of encouragement. Maybe phase-detect focus has been given a bad rap. Am I going to get a bunch of flak for daring to say out loud that phase-detect can work just as well as contrast-detect?

If you to take a look at many of my articles where I measure lens resolution, it becomes obvious that many lenses are poor at their edges. Numbers can be a bit deceiving, however. The world is, of course, three-dimensional. But all of the lens analysis articles you read present information to you in either one or at most two dimensions. Sure, you’ve probably seen lens resolution plots that are 3-D, but the data shown in them still represents only two-dimensional measurements. Sometimes, a lens has “hidden” resolution. The extra edge resolution is merely bent from the flat plane where the measurements are taken. This is what we call “field curvature”. Older lens designs, particularly in lenses with larger apertures, often suffer from excessive field curvature. Sometimes, even very expensive modern optics have this same problem. For instance, the new Kepler space telescope suffers from this issue, but the designers avoid the loss of edge resolution by making the image sensor curved to exactly match the optical field curvature. For a camera with interchangeable lenses, customizing the shape of the image sensor to match the shape of the lens optimum resolution zone just isn’t practical. The sharpness problem in most cases is minimized by selecting a narrower lens aperture. This solution, however, negates the whole reason for buying your (usually expensive) wide-aperture lens. Lens Resolution 3-D Plots (Meridional upper and Sagittal lower) The lens resolution plots look like 3-dimensional information, but they’re actually only 2-dimensional information taken from the flat camera image sensor. The red colors are higher resolution; the blue colors at the frame sides are lower resolution. Any way you look at it, the edges of the lens results look pretty bad. This (50mm f/1.8) lens may be capable of more resolution on the sides than you think, though. Lens Field Curvature Ray Trace Shown above, the zone of sharp focus for a lens with heavy field curvature doesn’t stay in a plane at the image sensor. Instead, the zone follows a curve (a bowl shape in three dimensions). The curvature might even follow a more complex shape, such as the 3-D plot above, for a multi-element camera lens. How to visualize the shape of the zone of sharp focus If you want to see if your lens has field curvature (as opposed to some other optical defect) that causes unsharp pictures at the edges, what follows are a couple of techniques to do just that. Make sure you shoot test shots with the lens wide open, to see the curvature with maximum effect. The more you stop down a lens, the more the curvature will be hidden, due to the increased depth of focus. Choose a subject that has many, many edges. In my sample shot below, I simply took a picture that is (flat) lawn grass. Lawn grass, Nikkor 50mm f/1.8 Now that I have a shot with lots of little blades (edges) in it, I need a way to enhance those edges. By enhancing the edges of a subject that stretches across the whole field of view, I will be able to visualize the shape and also the depth of what’s in focus. Edge enhancement is built into many photo editor programs. One of the most popular editors that possess edge enhancement features is Photoshop. For this article, though, I’m using Corel Paint Shop Pro, which has many of the same capabilities as Photoshop. Enhanced Edges To make the picture above, I took a lawn grass shot and then selected Effects | Edge Effects | Find All in the editor. There are similar options, such as “Find Vertical” and “Find Horizontal” instead of “Find All”. Choose whichever option best shows the high-contrast edges. Note that I ended up with a “U” shaped band of focus. This shows how the lens field curvature causes the zone of sharp focus to move away from the camera image sensor the farther you move toward the edges of the frame. Instead of just getting out of focus, the focus shifts where it is located. If I were to take a group shot of a bunch of people standing side-by-side, more people would be in focus if they stood along a “U” shape instead of standing in a straight line. For this lens, the people standing on the ends of the line would take a step further away from the camera. It would of course make a lot more sense to just stop down the lens to make sure a group of people has everyone in focus. If you wanted to artistically throw the background out of focus in your group shot, however, you’d have a problem if everyone was lined up straight. Visual Field Curvature with Live View “Focus Peaking” My D850 has Live View focus-peaking. If I turn it on (with “high sensitivity”) and also set my camera to manual focus, I can see the same enhanced edges right on the LCD. I see the characteristic “U” shape when looking at the same lawn grass scene shown above. This would be a realistic technique to determine if everyone in a crowd shot was in focus. That’s preferable to finding out after everybody’s gone home that people at the frame edges are out of focus. Whoops. Same “U” shape field curvature: focus peaking view in D850 Try shifting the focus farther away from the resolution chart To see if my “hidden resolution” theory is correct, I need to move farther from the resolution target and re-shoot it. If in fact the field is curved, then this should make the chart center have decreased resolution and the chart edges should have increased resolution, because the edges have been moved into the zone of where the in-focus areas are located. I won’t touch the lens focus ring or refocus; I’ll just move the camera/lens combination farther away from the chart instead. Target at calibrated focus distance from target: good center, bad edges Focus unchanged, but camera/lens is shifted farther from target You can tell in the charts above that the center resolution got worse as the camera was moved further from the target, since the center was now out of focus. Note, however that the edges/corners significantly improved in resolution. The 50mm lens was focused at 2.5 meters in both cases, but physically moved farther away by 3 inches (about 75mm) without refocusing. Conclusion If I were to make a lens resolution target that was shaped like a dome (or close to the 3-D plot shape at the top of this article), I could make this lens resolution look much more even from edge-to-edge. This would be the only way to really know how much resolution a lens (with field curvature) possesses at the frame edges using a single shot of the test target. I could alternatively take a series of shots of the flat target at different distances, like “focus stacking” does, and piece together the highest-resolving areas from each shot (entirely too much effort). The takeaway from this analysis is that lenses with field curvature don’t have the poor edge resolution that most reviewers quote! The resolution/focus has just curved away from a flat plane. It might be wise to shift the camera phase-detect focus calibration to an intermediate position between the frame center and the edge to balance out the resolution over the whole frame. howto

If you’re curious about how fast a lens can focus, a great way to measure it is to use slow-motion video. I previously used my smartphone video to do this job, but now I can use my Nikon D850. The D850 is capable of 120 fps video in DX crop-mode. This will allow you to time events down to a resolution of .0083 seconds. This is plenty accurate to measure your lens focus speed (lens is mounted on another camera body). D850 setup for slow-motion 120 fps video The overall testing scenario goes as follows. Mount the camera/lens you want to measure on a tripod, and set the focus ring to minimum focus. Make sure the lighting level is set how you want it; dim illumination will of course result in slower-focusing rates. Mount the D850 on another tripod (or hand-held if you’re careful), with its lens focused on the lens focus scale under test. Start the (120 fps) video recording, and then initiate focus on the target camera. Stop recording after the target lens is focused. Make sure the target camera/lens is pointed at something at a long distance, so that its lens will have to move from minimum focus to infinity. I’d recommend the target camera have “AF-ON” programmed onto a button, so you can just press that button to start focus. The recorded video should capture the entire focus sequence, so that you can watch the lens focus scale while it changes from minimum-focus to infinity. The slow-motion video can also capture any focus hesitation or focus “chatter” problems that your un-aided eye cannot detect. Not all lenses have focus scales, of course, so you might have to improvise on tracking what constitutes focus activity. The D850 video doesn’t need to be transferred onto a computer for analysis. You can play back the video recording in-camera, using its multi-selector button. In-camera Video Controls in Video Playback Mode Multi-selector center button: play or resume play after a pause The center button is typically used to play/resume your slow-motion video at the configured frames per second Pause video. Use “forward” or “rewind” while paused for single-frame mode. Rewind the video (back up a frame if “pause” is active) Fast-forward (2X, 4X, 8X, 16X per press) or one-frame advance the paused video Start slow-motion playback if the video is already paused Monitor “beginning of video” indicator (top right of monitor) Last Frame indicator (top right of monitor) Evaluate the video Use the keys shown above to navigate around your video. Locate when the lens distance scale first starts to move in the video. Step through the video to locate when the distance scale reaches the infinity mark and stops moving. Knowing the number of frames (or right-arrow clicks), you can now easily determine how long it took for the lens to focus. At 120 frames per second, that equals 1/120 or 0.0083 seconds per frame. For instance, it takes 30 right-arrow clicks for 0.25 seconds. The math would simply be (30 * .0083) = 0.25 seconds. Review 120 fps video of a stopwatch running on a smartphone In the shot above, I paused the camera video at the frame showing 19.0 seconds, and then clicked the right-arrow on the multi-selector and counted the clicks until the smartphone stopwatch reading was 19.25 seconds. It took 30 clicks, just as expected. It's always good to double-check your work. I used to include a high-resolution timer display in my videos, which shows the elapsed time directly. Using the video navigation controls in the D850 make this additional complexity unnecessary. I did this test on my Sigma 70-200 f/2.8 Sport zoom at 200mm in fairly good light outdoors (the sun was at a low angle), and it took 43 clicks (frames) to go from minimum focus to infinity, or 0.358 seconds. I had previously measured this lens in really bright sunlight (using a stopwatch in the video), and it took 0.36 seconds. Pretty darn close. By the way, this current focus speed test was done using a D500. My previous tests were done using a D850. They’re supposed to have equivalent focusing capability, and this proves that claim to be true. Summary Not many Nikons can manage 120 fps video yet, but the options open up considerably for 60 fps video. Even 1/60 second resolution is pretty good for measuring focus speed, although you might miss some nuances involving focus hunting or focus chatter. Other camera models probably differ in how to review in-camera video, but the discussion above will hopefully give you enough detail to enable you to try it yourself on whatever camera you're using. You may have to transfer the video to a computer and analyze it there, if your camera doesn't include the necessary controls to review it in-camera. This in-camera frame-counting technique makes it really simple to determine focus speed. You could, of course time anything you want using this same technique. Happy testing. #howto

The Hoya Pro ND1000 is a 10-stop neutral density filter. If you like those shots with rivers that look like mist, this is what you use to make them. Ocean breakers that transform into blankets of fog become possible with this filter. If you need to reduce crowds around popular landmarks, this filter is just the ticket. Hoya ProND1000 filter There are many characteristics of extremely dark ND filters that are difficult for manufacturers to get right. Many ND filters suffer from color shift, usually toward pink or orange. Other filters play havoc with lens resolution. Some filters have poor anti-reflection coatings that cause ghost images. Neutral density filters that avoid all of these pitfalls can get quite expensive. I purchased an 82mm diameter filter, so it fits the largest lenses I want to use it with. For my smaller lenses, I have step-up rings to use this filter for anything down to 52mm. Step-up rings are really inexpensive and an ideal way to spread the cost of a single expensive filter over several lenses. I don’t mean to imply that this is the most expensive neutral density filter, but it’s not the cheapest, either. What follows is how I evaluated this filter manufacturer’s claims. I own a couple of other Hoya filters, and I haven’t been disappointed. Auto Focus Impact Can a camera still focus with a 10-stop filter on the lens? It’s a real pain to have to remove a filter to focus a lens, so of course I tested auto-focus. I used my D850 for testing, which can focus down to EV -4. Typical outdoor lighting with a low-angle sun is around EV +10. Since EV increments are in full stops, this means that a 10-stop filter will result in an EV around 0, or 4 stops brighter than the D850’s lower limit. Focus is no problem. Subject Framing without Removing the Filter? Yes, under most lighting conditions, you can still frame the subject without having to take the filter off of your lens. The trick is to switch to ‘live view’ mode and use your LCD screen if your optical viewfinder is too dark. In bright light, the optical viewfinder may be barely sufficient for framing. Viewfinder Eyepiece Cover Please remember to cover that viewfinder eyepiece. Long exposures will cause eyepiece light leaks to ruin your shots. If you’re lucky enough to have an eyepiece shutter on your camera, this is the reason for its existence. Long Exposure Noise Reduction You might start finding excessive bright pixels in your shots with really long exposures. Remember to turn on ‘long exposure noise reduction’ to get rid of those speckles. It will take twice as long, but it may be worth it compared to the amount of time wasted post-processing trying to eliminate them at your computer. Color Shift Analysis I’ll use a grey card to evaluate the color fidelity of the Pro ND1000 filter. For a completely neutral photo, the RGB peaks on a histogram should perfectly overlap. I made a white balance preset with no filter, using a grey card. After shooting the grey card, I then mounted the ND filter and re-shot the grey card using the same white balance preset. The only difference should be the longer exposure with the filter. Grey card with no filter preset white balance The shot above is a grey card using a preset white balance measured with the card itself. Grey card with ND filter, same white balance The shot above is using the Hoya ND filter, with the same white balance as the no-filter preset white balance. It’s a hair different from the no-filter shot, but still quite neutral. The same grey card shot indicates that the density across the filter seems even as well. Illumination characteristics seem the same in the shots with and without the filter. Histogram of grey card with no filter The shot above is the histogram with the white balance measured right off of the grey card without any filter. I used the white balance as-recorded from the raw file. Histogram of grey card using Hoya ND filter The shot above is the histogram using the Hoya Pro ND 1000 filter and the same white balance created from the “no filter” shot. The color transmission isn’t identical to ‘no filter’, but it’s reasonably close. Resolution Analysis A good filter shouldn’t cause any significant change in lens resolution. Physics being real, all filters will have some impact on your lens, but that doesn’t mean that it has to be objectionable or even noticeable. I’ll use the MTFMapper program and a large resolution chart to see how much degradation in lens sharpness this filter causes. Sigma 70-200 at 70mm f/4 MTF50 without filter Sigma 70-200 at 70mm f/4 MTF50 with ND filter Comparing the lens resolution results above (on a Nikon D850), there isn’t enough change to be able to visually tell the difference when using the filter. The MTF50 numbers show the barest hint of a resolution decrease with the filter. Physical Light Reduction It may seem silly to have to verify such a thing, but does the Hoya Pro ND1000 filter really cut the light level by 10 stops? I’m notoriously skeptical about claims, and just because it’s advertised as 10-stop, that doesn’t make it so. A quick way to evaluate photos is via the “Exif Tool”. I took a pair of shots using auto-exposure in sunlight. The exif data indicated the no-filter shot was E.V. 10.3 and the Hoya ND filter shot was E.V. 0.3, so the filter is exactly 10 stops after all. I suppose you could stack this filter with a polarizer or another ND filter if you need yet more light reduction, but 10 stops is enough for most situations. Filter Thickness and Vignetting This filter is fairly thick. It’s about as thick as a typical polarizer. Its (metal) mount is 2.0mm thick (not including threads), and happens to be exactly as thick as my Marumi DHG Super Circular Polarizer. This can cause some vignetting on super-wide lenses, so you may have to crop slightly if your lens only works with “thin” filters. Speaking of threads, this filter screws on and off very smoothly; the threads are precision. I also noticed that it has about a whole extra thread compared to most filters, which makes it very stable when attached. Summary The Hoya Pro ND 1000 filter can transform mundane shots into something magical, given the right subject (and given a tripod). Wind is your enemy; you might consider a shot with and without the filter to have options. I can totally recommend the Pro ND 1000. I wish its mount was a bit thinner, but keep in mind that this filter has to contain enough volume of dark glass to stop a serious amount of light. For photographers who do landscapes or architecture, a strong neutral density filter should be a standard part of their gear. And, once again, don’t forget that tripod. Samples Exposure: 13s f/16 ISO 64 in the sun I confess to using a bit of HDR to make this shot a little more dramatic. It’s the misty water that makes the shot, though. You just couldn’t do something like this without a really dark ND filter. You don’t necessarily want the longest possible exposure time for water; try a few different exposures to give yourself a selection. Fountain of mist Exposure: 30s f/9.0 ISO 32. Yes, my D850 “Lo” can go down to ISO 32. I used my Tokina 11-16 DX at 16mm. The Hoya needed a step-up ring to fit my 82mm filter onto my 77mm diameter Tokina. I had to crop a bit, because this combination causes some dark frame corners on my FX camera. Luckily, the cloud movement was minimal and the sky retains good texture and depth. Ghosts around a pool Exposure: 177s f/10.0 ISO 32. The outrageously long exposure didn’t totally get rid of the crowd around the pool, but it did make about 95% of them disappear. The heavy clouds combined with the ND filter allowed this long exposure time. A light breeze caused many palm fronds to smear; oh, well. The clouds unfortunately moved too much in this long exposure and became featureless. This shot then demonstrates the downside of wind during a long exposure. #review