Most camera manufacturers designed their mirrorless cameras to focus with their apertures wide open. Nikon doesn’t do this with their Z cameras; they autofocus at the shooting aperture instead. Who’s right? Huge spherical aberration: Nikkor 85mm f/1.4 AF-S All DSLRs autofocus with the lens aperture wide open, because the partially-silvered mirror over their focus sensors causes really dim light. Dim light causes slower or failed focus. Wide-open apertures give a camera the best chance for fast or successful autofocus. Why wouldn’t all manufacturers always autofocus this way? Read on. Most high-speed lenses (f/1.4, f/1.2 or faster) suffer from something called spherical aberration. With this type of lens, the focus will shift when the aperture changes. This focus shift ruins shots, particularly at close focus distances. Spherical aberration As shown above, the best focus happens at the location of what’s called the “circle of least confusion”. This circle location shifts as the lens aperture changes, blocking light from the outer fringes of the lens. The circle of least confusion typically doesn’t shift much after the aperture is stopped down beyond roughly f/5.6. The Nikon Z (mirrorless) cameras stop the lens down to the shooting aperture to autofocus, up through f/5.6. They don’t stop down the aperture beyond f/5.6 while focusing, in order to retain acceptable focus speed. They of course stop down to the requested aperture when the shot is captured. Because of the way the Nikon Z cameras autofocus, focus is always correct when using lenses that have spherical aberration, no matter which aperture is selected. At apertures beyond f/5.6 (such as f/8) any additional focus shift gets “repaired” due to the large depth of focus that masks the focus-shifting error. It turns out that focus speed is not a problem with a stopped-down lens until the ambient light levels get really dim. Nikon has determined that this is a good trade-off, especially since most photographers will open up their lens apertures in dim light anyway. I have the Nikkor 85mm f/1.4 AF-S lens, which has pretty severe spherical aberration, and therefore severe focus shift problems. I had nearly abandoned using the 85mm when I would want to shoot at any aperture other than f/1.4. The pictures were always out of focus at other apertures, since I had calibrated focus at f/1.4 on my DSLRs. I actually carried around notes that indicated what calibration values to use for which apertures on which cameras! Very, very irritating. Using my Z cameras, focus is nailed every single time at any aperture. I have never had any complaints about autofocus getting sluggish at any aperture with my Nikon Z8 or Z9, until the ambient conditions get really dim. Since I use wide apertures in dim light anyway, Nikon’s choice to focus at the shooting aperture is optimal for me. I recognize that there is a theoretical advantage of always focusing with the lens wide open, but for me Nikon’s method is the preferred design choice. A side benefit of always having the lens stopped down to the shooting aperture (again, through f/5.6) is that I always view the actual depth of focus in the viewfinder as well. I can’t see ever using my DSLRs with my fast lenses again. They’re fine for many shooting applications, but this definitely isn’t one of them.

This article explains how you can create a panorama that actually captures mild action. The thing that keeps photographers from making successful motion-freezing panoramas probably isn’t what you think it is. Panorama with ‘frozen’ water ripples When I first attempted to shoot panoramas that could freeze moving subjects, I knew that it would take a camera that could produce a fairly high frame rate, such as at least 10 frames per second. You need to sweep your camera across the whole scene in less than a second, or else moving objects won’t align from one frame to the next. You also need about a third of each frame to overlap with its neighboring shot, or else your panorama-stitching software will probably fail to combine the photos. I quickly found out that you’re probably going to need something like a 20 fps frame rate to get a decent shot overlap, unless you are using a wide angle lens. I prefer to shoot panoramas in portrait orientation, which requires even higher frame rates than landscape orientation. When you pan the camera at a slower pace to accommodate slower frames per second, image motion between frames will cause moving subjects, such as water ripples, to no longer line up in the stitched panorama. With a bit of practice, you can learn to quickly sweep the camera across the field of view and get the necessary shot overlaps. If you stick with panoramas of about a dozen shots in portrait orientation, this means that you can go up to roughly a 120mm focal length at 20 fps. I tried using shutter speeds around 1/2000 and 1/3000 to “freeze” the action. Looking up close at my shots, I found out something that was very disappointing. The photos had terrible motion blur. What’s going on??  I hadn’t stopped to think that the subject motion while quickly panning the camera is on a whole other level. It turns out that you need shutter speeds typically beyond a 1/10,000 of a second to rid this motion blur. My Nikon Z9 and Z8 cameras can go up to 1/32,000 second, so no problem. I now standardize on using at least 1/13,000 shutter speed to reliably rid any blur, but it of course depends upon just how fast you pan the camera. Seamless motion capture In the shot above, I was using a 120mm focal length in portrait orientation. I swept my Nikon Z8 in an arc that took 0.6 seconds to complete, using a 20 fps frame rate. I shot in aperture-priority mode, and each of the 12 frames was taken at between 1/13,000 to 1/16,000 second shutter speed. I got decent frame overlaps at this pace, even in portrait orientation, and motion blur was eliminated. This shot is a demonstration of how the water ripples are seamlessly stitched together (using the Capture One editor). Even at pixel-level magnification, there is no motion blur. The Z9 and Z8 cameras can go up to 120 frames per second, but only when shooting jpegs. I’d rather have the quality of raw photos and sacrifice a little speed. For capturing really fast action in a panorama, you would be forced to go this jpeg route, however. Summary If you want to pursue doing this kind of photography, it means that you’re going to need a camera capable of producing both a very fast shutter speed and a high frame rate. I’d recommend plenty of practice shooting, to get the hang of achieving the correct shot overlap while whipping the camera around in a fraction of a second. You can of course use shorter focal lengths (and landscape orientation) to be able to shoot at a lower frame rate, but the shutter speed still needs to be quite fast to avoid motion blur. Photographs of this type simply weren’t possible to create before the introduction of very high performance cameras (or else synchronized multiple camera setups).

How do you get rid of every single annoying reflection, even from glass and metal? Product photographers are particularly interested in having the ability to completely control all reflections from the objects they need to photograph. The answer is polarized light. I’m not just talking about putting a polarizer on your camera lens; that’s only half of the battle. To totally rid all reflections, you also need to have your light source emit only polarized light. Annoying reflections that obscure your subject Everyone is familiar with the issue of not being able to photograph a shiny subject without having it partly obscured by lighting reflections. Most photographers are aware of using circular polarizing filters over their lenses to minimize reflections. Some subjects seem to defy every effort to totally rid reflections off of them, no matter how carefully you adjust the lighting or the shooting angle. The shot above shows an annoying halo of reflected light from a circular artificial light source (at between 2 and 3 o’clock) without using a polarizer. Circular polarizer The image above shows a typical circular polarizer. Years ago, you could only buy “linear” polarizers, which turned out to mess up the autofocus/exposure meters on DSLR cameras. They started making circular polarizers, which fixed this issue. These filters really help to minimize reflections, such as from pond surfaces or windows. Using a polarizer filter over the camera lens As seen above, a polarizer over the lens was rotated to minimize the reflections, and it really helps. But there is still an unwanted reflection at about 2 o’clock on the outer dial of the watch. There's also a sheen over much of the face of the watch that I'd like to eliminate. Double-polarized light: no more reflections! In the shot above, I placed a polarizer over the light source itself, being careful to stop any light leaks coming from around the edges of the polarizer sheet.  I made sure that there were no other lights on in the room. I then rotated the lens polarizer filter until I observed the removal of any reflections. You can buy inexpensive polarizer film sheets (‘linear’ polarizers will work for this application) to cover larger lights or flash units. Just make sure you don’t have any light leaks, because they can cause reflections. If you want to use multiple lights, you may have to ensure that each light polarizer is rotated individually so that the polarization is in the same direction. Summary If you didn’t know this little trick, it could drive you crazy trying to get rid of reflections. Double-polarized light can seem like magic, and drastically improve shots of things such as jewelry.

There’s a trivial-sounding feature that can be accessed only through assigning a custom control called “Recall Shooting Functions”. This feature is available on only a few Nikon ‘pro’ models, beginning with the D5. This is in fact a major and wonderful feature. In this article, we’ll explore just what you can do with this capability. Recall shooting functions feature On many ‘amateur’ Nikon bodies such as the D7000 series, they provide a dial with user settings called “U1” and “U2”. With these settings, you can switch most of the camera shooting configurations by merely rotating the dial. This makes it trivial and fast to switch between things like manual landscape settings and automatic sports shooting. This is an awesome feature that I love. On the top-end Nikon pro bodies, they instead have provided the tedious ‘settings’ banks, which are then sub-divided between “photo shooting menu banks” and “extended photo menu banks”. I have always hated this scheme, but have had to live with it. “Recall Shooting Functions” has changed that. Now, you can merely assign a button that you press to toggle between two independent sets of shooting features. If anything, this is even better than having to rotate a dial to use the “U1” and “U2” shooting setups. Your eye doesn’t need to leave the viewfinder to switch between two camera shooting identities, as long as your finger can find the assigned button. A word of caution, though. There are many actions that will ‘cancel’ the recall feature, such as cycling camera power. If this happens, then just press the “Recall Shooting Functions” assigned button again to re-activate the settings. First, let me explain how to configure this feature. Locate the ‘Controls’ menu F2 Custom controls (shooting) menu Pick a button to assign the feature (video record button) Select the “Recall shooting functions (hold)” option Pick the options to save (screen 1) Pick the options to save (screen 2) Pick the options to save (screen 3) Note that there are many functions that you have the option of saving for recall, such as the White balance and AF subject detection options. In my own selections, I decided to not save the White balance (no checked box) and I did decide to save the AF subject detection options (checked box). For convenience, you can just select “Save current settings” to save all of the present camera settings for each menu option at once. Sample setting: AF subject detection options Since I did decide to save the AF subject detection options, I pressed the right-arrow and was presented with the screen shown above to select which option I wanted to save (Auto). The “Video Record” button As shown above, I decided to use the Video Record button for assignment, because it’s easy for my finger to locate it while looking through the viewfinder, and it doesn’t affect video recording, since this Recall feature is only used while shooting stills. Sample shooting setup BEFORE pressing button Shown above is the shooting screen before pressing the assigned Video Record button. This screen shows that I am in “people detection” subject detect mode and 5 fps, for instance. Sample shooting setup after pressing button Note above that after pressing the assigned Video Record button, I got switched into Recall Shooting Functions mode. The subject detect mode is now “Auto” instead of “People”, and single-frame shooting is selected instead of 5 fps. Also note the icon that indicates that Recall Shooting Functions is active. This icon is displayed in both the rear LCD screen and the viewfinder. Get used to confirming that the little Recall Shooting Functions icon is displayed, since several camera operations can cancel this mode. This icon gets displayed even when you choose a display mode that doesn’t show any other viewfinder information. Summary You can’t save and toggle all camera shooting settings this way, but at least the most important features can be saved. Try out this feature. I bet you’ll decide that it’s the superior method to swap out shooting functions when you don’t have time for wading through those irritating Shooting Menu banks.

Sharp photos depend upon sharp focus. You might be very surprised at just how sensitive your lens can be to focus changes. I wanted to show you an experiment that gives very precise numbers on how the resolution changes with errors in focus. Nikon Z8 camera mounted on a linear slide As shown above, I start by mounting my camera onto a linear slide. This slide can be moved with a micrometer in very small steps, so that I can shift my cameras’ focus very precisely. I conducted these tests using a 135mm lens at f/2.8 mounted on my Nikon Z8. Note that this isn’t a particularly fast lens, but even at f/2.8 you’ll find that focus precision matters enormously. Using the MTFMapper program created by Frans van den Bergh, I repeatedly photographed a new utility knife blade at different distances and then processed the photos in his software. I focused the lens only once, while the linear slide was near its midpoint (12mm), before starting the test. I could have of course used a more conventional focus chart to get the resolution measurements, too. A utility knife blade in silhouette The subject, shown above, is the edge of a very sharp and straight knife blade. The software doing the analysis is capable of analyzing a single edge that you specify. To get the best results, the edge should have high contrast; I used a light to make the blade show up in a silhouette. If you look very carefully, you can see the little number 37.6 shown on top of the blade edge, which is where the software made the resolution measurement. Since MTFMapper uses LibRaw to decode raw files, it uses zero sharpening (sharpening would falsely increase resolution measurements). For raw formats that LibRaw doesn’t support (such as the Z8/Z9 high-efficiency raw), I use the Adobe DNGConverter to make DNG raw files; these files also have zero sharpening applied. The downside to this DNG converter program is that it strips out some exif data, such as the focus distance. Resolution versus focus distance As shown above, I made a plot of the measured resolution of the blade edge photographs at different distances. I had attempted to focus the lens while the camera was placed at a setting of 12mm on the linear slide rail. The measurements show that in fact the sharpest photo was at a position of 15mm, where I got an MTF50 resolution measurement of 37.6 lp/mm. The entire range of the focus testing shown is only about 1 inch (27mm). I had missed focus by only 3 millimeters, while my subject was at a distance of 7 feet (2.13 meters). The MTFMapper program is able to tell the difference in resolution even with a 1 millimeter focus error! I had used “focus peaking” with a magnified view and manual focus to get the best focus I could manage. The camera focus-peaking feedback (set on ‘low sensitivity’) got me to within about 3% of optimal focus. Granted; these resolution differences are finer than what you can probably perceive yourself, unless you need to crop or print big. Also, telephoto lenses are far more sensitive to focus errors. Summary Image sharpness is more sensitive to focus than most people could imagine. This little exercise shows why people that measure lens resolution have to be so careful in controlling focus (and vibrations), or else their measurements are just wrong. In a more general sense, you want those feathers, hairs, and eye lashes/reflections to be totally sharp. The best lens you can buy won’t give you that unless you also nail the focus. A cheap lens that is correctly focused will usually give better results than an expensive lens that is slightly out of focus. I have found that my mirrorless cameras achieve more accurate autofocus than my DSLR cameras, and my lenses don't need focus calibration on mirrorless, either.

I had heard a rumor that the Nikon Z9 “Bird” subject detection was usable for more than just birds. I have decided after my own testing that this is an understatement. You need this mode. Switch to this mode. Make sure you update your firmware to version 4.10 (or newer) to get this new option. For every animal, bird, or insect I tried, this mode was either superior or equal to any other subject detection mode. Except... BIF (bee in flight) not what you expected? Here’s a caveat, though. The Bird subject detection mode is worthless for people (I know, they’re animals too). Use either the ‘Auto’ (generic) or ‘People’ subject detection mode for people. I found it kind of amusing how the bird-mode frequently refused to focus on the eye of a person. Artificial intelligence is funny that way. For myself, I would rather use the “stupid” modes, such as dynamic-area or single-point autofocus for occasional people/landscape shots (assigned to different camera buttons), and just leave the subject detection mode almost permanently on “Bird”. If I were shooting sports (soccer, football, track, etc.) however, then I would of course switch to ‘People’ subject detection to cope with tracking rapidly-moving athletes. For Nikon Z8 owners: too bad. Maybe next year Nikon will get around to this firmware upgrade. ‘i’ menu for quick autofocus-area and subject-detect selection For quicker selection, I have set up my “i” menu to include the “AF-area mode”. This way, I use the back camera scroll wheel to select the AF-area mode, and the front camera scroll wheel to pick auto/people/animal/car/plane/bird. Subject detection is available when you use Wide-area AF(S)/Wide-area AF(L)/3D-tracking/Subject-tracking AF/Auto-area modes. The ‘i’ menu icon will show the latest AF-area mode selection type (3D in this case), but it doesn’t give you any hints about the subject type. Quick front/rear camera wheel selection in the ‘i’ menu The menu above shows that I have chosen ‘Bird’ subject detection and 3D-tracking AF-area mode. Setting up autofocus area modes outside of the ‘i’ menu Nikon doesn’t force you to set up the ‘i’ menu, of course. The regular menu-diving technique will also work perfectly fine to set up mode/subject combinations, after you navigate to the “AF-area mode” and the “AF subject detection options” in the “Photo Shooting Menu”. The little icon above shows that the present AF-area mode is ‘single-point’. Picking subject detection mode outside of the ‘i’ menu Available subject selections now include birds Note that “Auto” above doesn’t mean “automobile”, but “generic” instead. My own most-used AF-area mode: 3D-tracking I definitely use the 3D-tracking mode the most, so I assigned that to my AF-ON button. Thankfully, bird-detection is allowed in this focus mode. I also like to use the custom wide-area AF, and bird-detect works there, too (assigned to another button). Summary Give this new ‘bird’ mode a try. If you photograph any kind of non-human animal, I bet you’ll like it. Artificial intelligence is quite fickle, though, so I’m sure there are animals that will fool this detection mode. Choice is a great thing, and multiple button assignments are, too. I'll bet that each new firmware revision will alter the subject detection capabilities, because Nikon is training its AI with more and more subject samples.

Do all of the photo editors create panoramas that are roughly equal? This article explores how well some popular editors make panoramas, or at least how they try to make them. A sample panorama made from 5 vertical shots I did a little comparison between Lightroom, Capture One 2023, and ON1 2023. I wanted to figure out if I have a preferred editor for making panoramas, among my most-used photo editors. For starters, I gave each editor the same set of 5 photographs that have plenty of overlap between them, so it shouldn’t be too challenging to stitch them together. ON1 Photo RAW 2023 First up to bat is the ON1 editor. Pick the shots to combine from the ‘Browse’ tab To make panoramas in ON1, just click the “Create Panorama…” after selecting the shots in the “Browse” tab. Create Panorama dialog with “Auto” By default, ON1 will offer the “Auto” option to automatically select how to create the panorama. Unfortunately, this selection is a big failure; the last shot in the set of 5 shots was omitted. ON1 “Collage” option Selecting the “Collage” option, the results are even worse! This time, it skipped the last shot and couldn’t even align the left side properly. ON1 “Spherical” panorama success? ON1: A glitch in the stitch At first glance, the ON1 “Spherical” mode seemed to do the trick. Upon closer inspection, I found a mistake in the stitching that I indicate above. I’m out of options with ON1 panorama stitching, so it has failed. Three strikes. Capture One 23 Next up is Capture One 23. Capture One 23: Combine the shots in the “Library” tab As shown above, select the photos in the “Library” tab, then select “Image | Stitch to Panorama…” Capture One “Cylindrical” option Capture One “Spherical” option Capture One “Perspective” option Capture One “Panini” option Capture One cropped and light-adjusted panorama All of the Capture One options succeeded, but I need to mention that this program is slow in stitching the finished panorama, unless you have a pretty fast computer. In the shot above, I did a little editing to touch up the picture to taste after generating the panorama. You might notice that it’s actually a double rainbow. Lightroom Finally, let’s see what Lightroom can do. Lightroom: Photo merge panorama from the “Library” tab Lightroom “Cylindrical” option Lightroom “Spherical” option Lightroom “Perspective” option Lightroom cropped and light-adjusted panorama Similar to Capture One, Lightroom made no mistakes in any of the projection options for the panoramas. I didn't try to exactly match the light in my Capture One version of the panorama; this version is very close to what my eyes saw. Multi-row panoramas Since ON1 is out of the running, I decided to see if Lightroom and Capture One could handle multiple-row panoramas. Both programs failed when I tried the “perspective” projection method, but both programs succeeded when trying either “spherical” or “cylindrical” projection. It’s easy to have several shots lost in the final stitch, if your goal is to end up with a rectangular photo. You have to be careful to go well beyond what you think might be okay for the stitched area. I’d recommend using a tripod for any multi-row panorama efforts. It’s too difficult to control the shot overlaps in both the horizontal and vertical directions when hand-holding the camera. Against my own recommendations, I hand-held all of the panorama shots in this article... Lightroom multi-row, using “spherical” projection Capture One, “spherical” projection Note how the un-cropped result has the tree tops well inside the stitched panorama, so you think all is well… Capture One, “spherical” projection cropped to a rectangle Dang it, the tree tops got lost after all. Should’ve brought a tripod along. There's a school of thought that you should just leave your panoramas un-cropped and get away from rectangular format; I just can't go there yet. Summary I noticed that Lightroom created the panos a bit faster than did Capture One. ON1 was the fastest editor of the three I tried, but it doesn’t count when the panoramas have defects. Capture One had the most projection options; it kind of depends upon the subject matter which projection method looks best for a shot. I can’t say that either Lightroom or Capture One wins; they are both very competent at making panoramas. For multi-row panos, I have historically had slightly better success using Lightroom. It’s a good thing that I didn’t buy ON1 for its panorama capabilities (I got it mainly for the sky-swapping feature). ON1 2023 struck out for this particular task.

I have read claims on the internet that printed test charts are nearly worthless for use in measuring lens resolution. I have also read that a sharp razor blade or utility knife blade can be used to get really accurate resolution measurements. Which claim is true? Both? Neither? I use the MTFMapper program to analyze lens resolution. NASA has used the MTFMapper program to analyze lenses that they sent to Mars onboard their Rover Perseverance. I don’t think that this program is providing bad results. The software can be obtained from here. You should be very skeptical of internet sites that don’t tell you how they arrived at their resolution numbers. A sample resolution test chart MTFMapper provides printable files, which I used to make my test chart targets. This same software provides a way to use things such as back-lit razor blades or utility knives for resolution targets. The target edges being measured are all on a slant; the measurement mathematics doesn’t like edges that are vertical, 45 degrees, or horizontal. I believe that MTFMapper uses LibRaw to decode raw files, which uses zero sharpening (which would increase resolution measurements). For raw formats that LibRaw doesn’t support, I use the Adobe DNGConverter to make DNG raw files; these files also have zero sharpening applied. The downside to the DNG converter program is that it strips out some exif data, such as focus distance. For sites that use other camera photo file formats, particularly jpeg, resolution measurement results are worthless. Just about all of these formats add some level of sharpening. Depending upon the amount of sharpening, you can make the resolution measurements as high as you wish. I use a printed test chart that measures 40 inches by 56 inches. The chart is printed at 1200 dpi on heavy-weight paper with a fairly glossy finish. The chart is dry-mounted and placed into a frame to keep it perfectly flat, and I temporarily mount a mirror to the center of it using magnets to align my camera and get it perfectly parallel to the camera sensor. The chart is clamped into position to eliminate any movement, and the camera is on a heavy tripod. I use either a wired shutter release or a self-timer, using either live view or a mirrorless camera to eliminate vibrations. Chart lighting needs to be even, and it’s best to keep illumination levels above at least EV 10. Surprisingly, the ISO value has little effect upon resolution measurements; it’s still best to keep the ISO low. A sample setup to use a quality blade edge for a resolution target I conducted some tests to compare resolution measurements using my chart and a pristine utility knife blade. I can’t prove resolution results in an absolute sense, but I can at least compare results from two entirely different test methods. When I first started doing resolution testing, I tried using small (11” X 17”) printed charts, both with inkjet and laser. I also tried matte/glossy/satin surfaces and single/double weight papers. I determined that laser prints weren’t quite as good as inkjet, and that satin-like surfaces worked best. Small charts are poor for testing lenses at realistic shooting distances (you want to fill the frame with the chart if possible). I’m forced to use laser prints for infrared testing; my inkjet ink is invisible in infrared! I always struggled to accurately align the test chart to the camera until I began attaching a mirror to the chart surface (using powerful magnets). When you can see your own reflection looking through the viewfinder and the lens center reflection is in the middle of the viewfinder, you’re perfectly aligned. Rotation is easy; just align the chart edge to the viewfinder edge. The MTFMapper program will change the color of the resolution measurements to yellow for edges that end up at a poor angle. Camera (Nikon Z8) mounted on an accurate sliding linear rail Accurate focus is an absolute requirement to get the best resolution measurements. It’s possible, using contrast-detect focus or a mirrorless camera with autofocus, to get reasonably good focus. I can get a bit better focus using low-sensitivity focus-peaking and image magnification. It’s necessary to take several shots, with focus set both in front and behind the target before re-focusing. You need to pick the sharpest results from the many test shots, and make sure the focus is done at the shooting aperture The best way to get optimal focus is to use a linear rail and move the camera in very small (1 mm or so) increments starting in front of the subject correct focus and taking shots until you’re behind the subject focus plane. Again, pick the sharpest result (highest measured resolution). Select where to take the measurement The photo above shows how to pick where to take a resolution measurement along the knife blade. Choose a location and orientation to match a similar edge in the resolution test chart. Selecting a different section of the blade will probably give slightly different measurements, because the MTFMapper program is supremely sensitive to edges. The illumination behind the blade only needs to be even in the selected region of interest that is being measured. You want to do this in a dark place, to maximize the silhouette contrast. Note that every position and orientation in the camera’s field of view will likely give a different resolution reading. Life and physics isn’t as simple as what is portrayed at most photography websites. A single resolution number is nearly meaningless (as is a single center/edge/corner number). Also keep in mind that different camera sensor resolutions will give different answers as well, because the resolution measurement is actually a combination of the lens and the camera sensor. Blade Placement Blade placed near to chart target edge in viewfinder As shown above, I placed the blade edge in a similar location to a chart measurement that I was interested in comparing. I tried to select the section of the blade edge in MTFMapper that would roughly match the length of the chart target edge (about half of the blade edge length). Blade placement relative to test chart placement As you can see above, I have drawn in roughly where I placed the blade in the camera viewfinder that I measured in red. The little cyan numbers are the MTF50 resolution measurements on every target edge in the chart, as calculated by MTFMapper. A potential upside to using a blade edge is that you can focus on it wherever you place it in the frame. For lenses with field curvature, this will probably get you a higher resolution measurement than simply using a chart that you probably just focused in the frame center. A downside to using the blade is that you get a single measurement from your photograph, versus over 700 measurements by using a chart like that shown above. Comparison Results I decided to use my Nikkor 24-120mm f/4 S lens on a Nikon Z9 camera to compare resolution test results between my printed chart and the blade. The lens was zoomed to 34.5mm (the lens barrel marking was 35mm). The MTFMapper program was configured to provide resolution measurements in units of MTF50 lines pairs per millimeter. I like to use these measurement units, since you can get the same answer using any size of camera sensor. MTFMapper measurement of blade edge: 34.5mm, f/4 Pretty comparable measurements between the blade edge and the chart! Summary Although none of what I have written can absolutely prove that I’m getting correct lens resolution measurements from my printed test chart, I think it shows that the measurements are at least in pretty close agreement between these two very different test methods. A site that I use to compare by own lens resolution results against the same lens models is Lenstip, found here. They also measure resolution in units of MTF50 lp/mm, and our results are typically very comparable (when using similar camera sensors). Lens sample variation is a real thing, so you should never expect to see the exact same results between any two lenses.

Nikkor Z 24-120mm f/4 S, mounted on Nikon Z9 I have heard so many good things about this lens for so long that I finally got one. Since I already have the very professional AF-S Nikkor 24-70 f/2.8 ED VR, it would seem a mostly redundant acquisition. Yes and no. I have a dedicated infrared F-mount camera, and that 24-70 is nearly always parked on it. Since the Z 24-120 has a different mount, that IR camera won’t ever see this lens; pity. Before I digress too far, let’s get back to the subject at hand: the 24-120 f/4 Z lens. This is a true walk-about lens which goes wide, telephoto, AND macro. I’ll show some shots later that prove the point. By definition, 5X zooms produce images that are crap. Right? Not this one. It beats my 24-70 f/2.8 F-mount lens at every f-stop and focal length for resolution. It is even slightly sharper than my Micro-Nikkor 105mm f/2.8 AF-S VR, at least in the central part of the image. I got this Z lens for HALF the price of what the 24-70 f/2.8 AF-S lens goes for these days (which I actually paid $2,400 for). So what’s missing here? 24mm setting Note that you can see the entire range of zoom settings above (about a quarter turn). I included the lens hood; you should, too. 120mm setting Notice the two telescoping pieces that make up the zooming portion of the lens. Nikon claims that the lens is still entirely weather/dust sealed nonetheless. Shown: lens controls Shown above left-to-right: Focus ring Zoom ring Lens function button (L-Fn) Lens control ring A/M switch What’s NOT included with this lens? This Z lens has no VR, but my Z9 and Z8 bodies both have IBIS; for me this is a “don’t care”. For you, it may be important. This lens has no focus scale. It messes up my ability to measure focus speed by filming a slo-mo video of the lens focus scale in motion, but otherwise it’s a “don’t care”. No quality lens case. It comes with a nearly useless flimsy pouch without even a drawstring. I have several really good lens cases, so again I don’t care. Lens Specifications · Weight: 1.39 lbs., 630g. (24-70 f/2.8 F-mount is a huge 1067g for comparison) · Dual stepping motors for internal autofocus (almost perfectly silent and super fast) · 77mm filter threads · ARNEO/Nano crystal/fluorine coating: repels dirt; very little flare. · 9 rounded blades, electronic aperture (circular out-of-focus lights) · 3 ED glass, 3 aspherics, 1 ED/aspherical combination lens element. Sharp! · Total lens elements: 16, 13 groups. · Constant-aperture f/4 (all focal lengths). Minimum aperture f/22. · 1 programmable lens function button, e.g. “AF-ON”. · A/M focus switch. “M” will stop autofocus behavior. · 1 programmable lens control ring, e.g. a real aperture control! · Metal lens mount, mostly high-quality plastic exterior. · Moisture/Dust sealed. No Nikon refunds for H2O damage… · Minimum focus: 35cm/1.15 ft. (0.42X at 120mm, measured) near-macro! · Length: 118mm, 84mm diameter · HB-102 plastic petal bayonet lens hood General Impressions The zoom ring on this lens is stiffer than any lens I have ever used. Getting to the nearest millimeter is a challenge. It takes about a quarter turn to go through the whole zoom range, so you can zoom very quickly. A sort of giveth and taketh away. The dual-telescoping zoom action has NO wiggle. This lack of wiggle is necessary to obtain the very high resolution at all focal lengths. This is probably why the zoom action is stiff. The astonishing close focus distance and 0.42X magnification at 120mm has enabled me to mostly abandon using my 105mm macro lens. I rarely need to get all the way down to 1.0X magnification, and the super high resolution allows for significant cropping. The intensely fast auto-focus lets me get macro action shots that I’d miss with my slower-focusing 105mm Micro Nikkor. With my usual editors (Lightroom, Capture One 23, ON1 Photo Raw 2023) the photos don’t show any vignetting or image distortion. The information embedded in the Raw images (I’m using either the “High Efficiency Raw” or DNG format) has distortion-correction information and vignetting-correction information. The editors auto-correct the images without asking. For my old version of Lightroom, I use the latest Adobe DNG converter to use my Nikon Z8 raw files as DNG and still get automatic distortion correction. Focus Speed Due to the lack of a focus scale and internal focusing, I haven’t figured out an accurate way of providing actual focus speed numbers. Suffice it to say that those dual stepping motors make focus really fast. A crude test I performed involved focusing at minimum distance on a close subject at a focal length of 120mm, start video recording at 120 fps, and then press the AF button while panning to focus on a distant scene. When I reviewed this video, it took roughly 57 frames, which is 0.48 seconds (in sunlight). Keep in mind that this lens focuses closer than most, so minimum-to-maximum focus range is much further than most lenses. For normal photography, you'll find the focus to be blazingly fast. Sample Shots 120mm f/4 1/800s bokeh example Bokeh circles can show slight edge brightness, and the frame edge highlights become non-round. Even the $8000 Nikkor 58mm f/0.95 Noct has non-round highlights at the frame edges, so don’t use that as a pass/fail test. After you stop down the aperture, the non-round edge highlights become circular, although of course they’re smaller. 120mm f/4 1/800s pixel-level crop from the shot above Note how sharp those feathers and eye reflections are in this 100% crop. This lens is sharp. I haven’t seen any “onion skin” in the highlights, which is something which really bugs me when it’s present in photos. Nikon Z8, 120mm f/5.6 crop from a close-up To my eye, this is as sharp as a good macro lens. I cropped some, but the resolution really holds up well. 24mm f/9 1/400s 24mm f/9 1/1600s 120mm f/7.1 1/1000s. Packard hood ornament 24mm f/7.1 1/500s (license plate altered) 80mm f/8 1/400s converted to black and white Infrared Performance For those of you that are interested in infrared photography, I tried out this lens with an 850nm infrared filter. This is very deep infrared. The lens passed with flying colors (except that ‘color’ is undefined in this part of the spectrum). No dreaded hotspots seen. 850nm deep infrared, 120mm f/5.6 180 seconds I had to use an infrared filter over the lens, since this Z lens won’t mount onto my F-mount infrared camera. Super long exposure, because the image sensor cover of the Z9 used in this test really screens out infrared. Lens Optical Characteristics 24mm f/4.0 “hidden” barrel distortion and vignetting I was able to “uncover” the actual optical distortion of this lens by converting the raw file into the Adobe DNG format, and then using my image-analysis software MTFMapper. As shown above, there’s hefty barrel distortion at 24mm. As you’ll see later, there’s pincushion distortion that’s pretty evident at 120mm. Again, you’ll probably never see this distortion in your photos, since most photo editors will automatically remove it. Relying on photo editors to remove optical distortion is getting more common all the time, and isn’t necessarily bad. Lenses would always be bigger, heavier, more expensive, and more complicated to totally rid this distortion purely through the glass. Lens designers are going to just embed the mathematics of the geometry corrections into the photo file (correction profile), so that editors can straighten curves, and even adjust transmission loss (vignetting). It only gets ugly when you’re using an image editor that doesn’t understand this embedded information. Resolution, Contrast, and Lateral Chromatic Aberration I use the MTFMapper program to perform resolution tests, which you can get here: https://sourceforge.net/projects/mtfmapper/ This image analysis program was used to measure the Z-cam lenses on board the Mars rover Perseverance. My resolution chart size is 40” X 56” to get a better working distance. My tests were done using unsharpened raw-format shots using a 45.7 MP Nikon Z8. The contrast plots are real contrast plots, and not the theoretical ones that lens manufacturers put out. They include the camera sensor effects, since you’re going to be using the lens with a real sensor. The MTF50 resolution plots, measured in line pairs per millimeter, are shown in both the sagittal and meridional direction across the whole field of view. Resolution is a 2-dimensional thing, and not a simple single number. I stop measuring after f/16, because diffraction destroys the resolution. MTF50 lp/mm resolution, 24mm f/4.0 Peak resolution, central = 76.4 lp/mm (3652 lines per pic. height) Peak resolution, worst edge = 57.9 (2768 l/ph) Peak resolution, worst corner = 43.2 (2065 l/ph) MTF Contrast plot, 24mm f/4.0 There’s definite astigmatism here, since the sagittal/meridional lines don’t overlap very closely as you get further from the lens center. The meridional (tangent) direction has less contrast and resolution than the sagittal (wheel spokes) for this lens at most apertures and focal lengths until the lens is stopped down typically beyond f/11. Lateral chromatic aberration, f/4 The worst (blue vs green) chromatic aberration is about -5.7 microns. The sensor has 4.35 micron pixels, so it’s 1.3 pixels worst case. MTF50 lp/mm resolution, 24mm f/5.6 MTF50 lp/mm resolution, 24mm f/8.0 MTF50 lp/mm resolution, 24mm f/11.0 MTF50 lp/mm resolution, 24mm f/16.0 MTF50 lp/mm resolution, 34.5mm f/4.0 Peak resolution, central = 72.7 lp/mm (3475 l/ph) Peak resolution, worst edge = 39.1 (1869 l/ph) Peak resolution, worst corner = 32.4 (1549 l/ph) (Like I said, zooming to an exact millimeter is very difficult on this lens.) MTF50 lp/mm resolution, 34.5mm f/5.6 MTF50 lp/mm resolution, 34.5mm f/8.0 MTF50 lp/mm resolution, 34.5mm f/11.0 MTF50 lp/mm resolution, 34.5mm f/16.0 MTF50 lp/mm resolution, 50mm f/4.0 Peak resolution, central = 77.4 lp/mm (3700 l/ph) Peak resolution, worst edge = 50.5 (2414 l/ph) Peak resolution, worst corner = 43.2 (2065 l/ph) MTF50 lp/mm resolution, 50mm f/5.6 MTF50 lp/mm resolution, 50mm f/8 MTF50 lp/mm resolution, 50mm f/11 MTF50 lp/mm resolution, 50mm f/16 MTF50 lp/mm resolution, 70mm f/4 Peak resolution, central = 65.2 lp/mm (3117 l/ph) Peak resolution, worst edge = 41 (1960 l/ph) Peak resolution, worst corner = 38.3 (1831 l/ph) MTF50 lp/mm resolution, 70mm f/5.6 MTF50 lp/mm resolution, 70mm f/8 MTF50 lp/mm resolution, 70mm f/11 MTF50 lp/mm resolution, 70mm f/16 MTF50 lp/mm resolution, 120mm f/4 Peak resolution, central = 66.5 lp/mm (3179 l/ph) Peak resolution, worst edge = 42.7 (2041 l/ph) Peak resolution, worst corner = 41.2 (1969 l/ph) 120mm f/4.0 “hidden” pincushion distortion and vignetting MTF Contrast plot, 120mm f/4.0 Lateral chromatic aberration, f/4 MTF50 lp/mm resolution, 120mm f/5.6 MTF50 lp/mm resolution, 120mm f/8 MTF Contrast plot, 120mm f/8 MTF50 lp/mm resolution, 120mm f/11 MTF50 lp/mm resolution, 120mm f/16 Summary It never occurred to me that I would use this lens for macro photography. The 0.42X magnification, good working distance, and fast focus has made it my go-to for most macro work. Most close-up photography doesn't really need to go all the way down to 1.0X. This lens really does compete with many prime lenses. It’s in the same ballpark for sharpness, and the bokeh isn’t that bad. And you just can’t beat being able to zoom over such a large and useful range. I didn’t fully appreciate how much better it is, compared to my 24-70 f/2.8 zoom, for sharpness, focus speed, focal range, and close focus. It would of course be nice to have the same f/2.8 aperture, but you can't have everything. Telephoto zooms are famous for being much worse at their maximum focal length. Not this guy. For those times that you can take only a single lens on a trip, this is it. It will handle everything except the really big glass required for wildlife. And it’s maybe a little long for architectural interior shots. The Z lenses, especially the ‘S’ line, have a reputation for being overpriced, but here’s a case where what you get is a real bargain. I got it along with my Z8, so I got an even better bargain. Sample Shots 95mm f/8 1/100s 96mm f/5.6 1/400s 120mm f/8 1/2000s

When you read about lens sharpness results on the internet, can you believe them? Maybe. I believe that you see more variation in lens resolution measurements at different internet sites than in the lenses themselves. What follows is a technique to inexpensively get some very accurate resolution numbers. At the core of my lens resolution testing is the program MTFMapper, written by Frans van den Bergh. His software, documentation, and printable test chart files can be found here. The MTFMapper program can do many different things related to camera lens testing, which includes resolution, contrast plots, sensor alignment, chromatic aberration measurement, and focus analysis. I’m only going to discuss resolution measurement in this article. There are many elements that are required to get good, repeatable lens resolution measurements. Normally, these elements include the following: Stable camera/lens support Quality test chart Even test target illumination Proper target alignment Precision linear rail with micrometer adjustment Un-sharpened, raw-format photos of test target In this article, I’m going to discuss a way to avoid the need for the “quality test chart”. Frans’ MTFMapper program will let you get by with only a single high-contrast edge to measure, which can be supplied by a simple razor blade or utility knife blade. A good reason that this option exists is because it isn’t trivial to get a large, accurately-printed, quality media, and properly-mounted test chart. I inspected a blade edge under very high magnification to convince myself that it had no defects or roughness that would degrade the measurement results of the program. A Sharp Target Edge The ideal lens resolution target is a chart with many edges that can be measured by the testing program. Although printable files are supplied with the program, those files still need to be printed and mounted. How big should it be printed? How good of a printer is needed? What kind of material should be used for the chart? How do I mount the printed test chart? These issues have kept many people from even attempting to make their own lens resolution measurements. A back-lit blade target It might sound a little crazy, but a really good target to test lens resolution is a razor blade, photographed in silhouette. The MTFMapper program has the ability to measure a single straight edge in a photograph. If you can provide a high-contrast, in-focus, very straight edge, then you can get a really good resolution measurement of that edge. In the photo above, you can see an example of how to mount a blade whose flat face is parallel to the camera sensor. I use forceps held with a clamp. If you look closely, you will notice a number superimposed over the razor’s edge that says “37.6”. This number is the MTF50 resolution value, measured in line pairs per millimeter (this is a very old lens that isn’t as sharp as modern lenses). A light was placed to cause the blade edge to be in silhouette, since you want a high-contrast edge to get a quality resolution measurement. The edge to measure can be placed anywhere in the photograph, which is handy when you’re interested in resolution in maybe a corner of the frame. You can also orient the edge to enable measurement in meridional (tangent) or sagittal (wheel spoke) directions. If your lens has a curved focus plane, then you can focus on the blade wherever it is located in the frame to get a better resolution measurement. An optimal edge angle is 5 degrees or 85 degrees, but the program is fairly flexible. Please avoid perfectly vertical or perfectly horizontal edges, due to the way the programs’ mathematics work. You don’t have to use the whole edge, either; you can measure just a piece of it. Take a photo of the edge in RAW format. You might need to convert the photo into DNG format, using the free Adobe DNG converter program, if MTFMapper doesn’t understand your camera’s raw format. Don’t ever give MTFMapper jpegs!!!! Since jpegs have varying amounts of sharpening applied, the subsequent resolution measurements using these files will be totally bogus and useless. The most reliable results are obtained by using a remote release or the self-timer and an electronic shutter or mirrorless camera and manual focus. If you take a few shots with the same setup but get different measurements, then the first suspect is unwanted vibrations. Edge measurement in MTFMapper To perform the resolution measurement, you need to do the following: In MTFMapper, first make sure the Settings,Preferences has the pixel size of your camera sensor (measured in microns). Select File | Open with manual edge selection… Browse to your camera’s RAW (or DNG) file of the blade The “Select one or more edge ROIs” dialog opens up (shown above) Left-mouse-click the beginning of the blade edge to measure Left-mouse-click the end of the blade edge to measure A small cyan rectangle is drawn over the region to analyze. Click the Accept button Open the resulting “annotated” file on the right-hand side of the program. If your lens is in proper focus and your camera is steady, then you should now have a very accurate measurement of the lens resolution at that location. Focus Aye, there’s the rub. If your photo of the edge to measure isn’t in proper focus, then the results turn into garbage-in-garbage-out. Camera mounted on a linear slide with micrometer You may think that using contrast-detect focus and/or focus peaking will get you perfect focus. Think again. It’s true that mirrorless cameras generally yield vastly better focus, but optimal resolution measurements actually require millimeter-level accuracy. Manual-focus lenses are even harder to focus properly. Shown above is a camera on a linear-travel slide controlled by a micrometer that is capable of repeatable movements as small as 0.01mm. Using a system such as this, it’s easy to make a series of photos that start before the expected correct-focus zone and then travel up to and finally past the zone of correct focus. Just let MTFMapper analyze each shot to let you find the peak resolution; it’s rarely in the shot you anticipated. I like to use focus-peaking to at least get the lens into the general zone of correct focus while in the middle of the focus rail travel. I manually focus with the least sensitive focus peaking level (1), and with the most screen magnification that still displays peaking. Sometimes I’m forced to use the ‘medium’ focus peaking level, because the magnified screen doesn’t display any peaking feedback. I have found that some lens/aperture combinations can show focus changes (and resolution changes) by movements as small as one millimeter, even when focusing on targets a few meters away. The MTFMapper program is sensitive enough to detect the smallest focus (and resolution) changes, well before your own eyes can detect it. Most lens focus rings are much too coarse to change focus by these small amounts, and autofocus is almost never this precise, either (even using pure contrast-detect). These fine changes will be lost if you don’t also trip the shutter using remotes/self-timers/mirror-lockups, etc. to rid any vibration. And turn off lens vibration reduction. Summary It doesn’t have to be very expensive or complex to measure your lens’ resolution. You mostly just need to have the patience to carefully align your target, control the lighting, and nail the focus. And never use jpeg for measurements.

If you have hundreds of raw photos that you want to edit and convert into jpeg, what’s the easiest way to do it? If you are using ON1 Photo Raw 2023, you can use their batch-mode feature that’s accessed through the Browser Thumbnail-View dialog. Make sure you’re in ‘Thumbnail view’ first Make sure you’re in ‘Browse’ mode, and NOT ‘Edit’ mode when you want to do batch-mode features. You also want to make sure that you’re viewing thumbnails of your photos, which is enabled as shown above. The “Thumbnail View Options…” dialog will pop up after you click your right-mouse button while in the Browse mode, after multi-selecting the shots to convert. There are actually a bunch of features available in this dialog, but I want to draw your attention to just a few of them. Rotate your photos to the proper orientation It’s important to note that before you start any photo editing, it’s handy to make sure all of your vertical-mode shots get rotated to the correct orientation. This can be done from the ‘Browse’ module. Start by multi-selecting the photos that need rotation in a particular direction. Next, click the right-mouse button to activate the “Thumbnail View Options…” dialog. Rotate to the correct orientation Near the top of the ‘Thumbnail View Options…’ dialog, you’ll see a “Rotate” option; from here you can select either ‘Rotate CW’ or ‘Rotate CCW’. I noticed that my shots actually needed to get rotated the opposite direction of the commands (rotate clockwise to get counter-clockwise rotation). Try a single shot to make sure it rotates as expected prior to batch-rotating hundreds of them. If any shots need rotation, get this done prior to converting the raw shots into jpegs. Batch-edit multiple files If you have a routine set of edits that will apply to several files, then do the following after editing a sample photo (in the ‘Edit’ module). Copy the active photo edit steps First, copy the editing steps from the active photo in the ‘Edit’ module by selecting “Copy Settings” as shown (or else click Ctrl+Shift+C). Second, leave the ‘Edit’ module and then multi-select the desired files in the ‘Browse’ module that you want to apply to the copied editing steps. Paste the edit steps into selected files Finally, as shown above ‘Paste’ the editing steps into your selected set of files (or click ‘Ctrl+Alt+V’). The selected collection of files will immediately receive the edits from the ‘Copy Settings’ step. You can verify that your photos received the requested edits by selecting a sample photo and look at the edit settings in the “Edit” module after the batch-edit process has completed. Batch conversion of Raw to Jpeg Batch-convert files via the ‘Export’ option After selecting the desired set of photos while in ‘Thumbnail view’, click the right-mouse button to see the dialog shown above. The Export Dialog When you click on the Export… item in the Thumbnail Options dialog, you’ll see the dialog shown above. You can export the raw shots into more formats besides jpeg. You also get to specify where you want the exported files to go; I like to place them into a sub-folder from my raw shots called “jpg”. I noticed that the dialog “radio buttons” don’t act like radio buttons; they act like checkboxes, where you can select more than a single option. You could export to both ‘dng’ and ‘jpeg’ at once, for instance. Progress dialog while converting selected photos As shown above, you’ll get a progress dialog while the batch process is executing, once you click the “Export” button. This way, you’ll know how long the conversion should take. If you now discover that ON1 is doing something unexpected, you can cancel the batch process. The ‘Export’ dialog also lets you tell ON1 what to do after finishing the batch process. I like to see the finished results in Windows Explorer, but you can also do things such as opening the shots in another editor. My version of Lightroom doesn’t understand my raw-format shots, unless I convert them into DNG; this is a handy way to get the raw (high-efficiency raw) converted into DNG and then automatically run Lightroom. Summary You can easily save hundreds of hours by batch-editing. It’s a fundamental skill that all photographers should get familiar with. ON1 Photo Raw 2023 provides these tools, although it's not very obvious how to use them.

Nikon has a very capable feature set to enable manual focus assistance called ‘focus peaking’. Unfortunately, the camera menu system wording almost guarantees using it incorrectly. Nikon Z9 rear screen focus peaking display As seen above, the image details that are in focus get a color outline around them; in this case they’re red. If you look closer, you should notice at least a couple of problems with what is shown. The first problem with focus peaking you should note is that many of the fine details are shown as ‘in focus’, even though they’re largely mush. Another problem is that the nearly-horizontal edges aren’t ever shown as being in-focus; only the mostly-vertical edges are indicated as being sharp. The Custom Settings Menu Let’s take a look at the camera setup menus that activate and configure focus peaking. Locate the ‘a Focus’ option First, locate the Custom Settings Menu, and then open up the Focus option. Nikon Z9 Option ‘a13 Focus peaking’ Next, scroll down to the Focus peaking option. Don’t bother looking for in-camera help to explain peaking; on my cameras, it offers no help. Turn on the Focus peaking display Be sure to activate focus peaking by turning it ON. After focus peaking is active, your camera display (viewfinder and rear screen) will show peaking whenever you twist the Z-lens focus ring. It will even work when the lens focus switch is set to “A” for automatic focus; you don’t have to switch to “M” for manual-only focus. Some F-mount lenses may require a manual-focus switch setting to get the peaking display, and most non-Nikon lenses will also require the ‘manual’ focus switch setting to get a focus peaking display. Focus peaking sensitivity Please remember this: when Nikon says “high sensitivity”, they mean LOW focus resolution! With wide angle lenses, a setting of “3 (high sensitivity)” will often mean that the entire frame is shown as “in focus”. You will almost NEVER want a setting of “3”; maybe save it for use on a foggy day. For most conditions, please set the peaking sensitivity to “1 (low sensitivity)”; this setting will be the best indicator of what is actually in focus. Even this setting using an un-magnified viewfinder can give you pretty sloppy focus results. Nikon came up with the “high sensitivity” descriptor due to how they implement peaking. Very small changes in illumination levels between neighboring (horizontal) pixels will trigger peaking if the camera is configured to have a high sensitivity to these small light changes. Unfortunately, this small-change condition rarely means that the lens is properly focused. Focus peaking color Nikon gives you 4 color choices for peaking. With this, you can adapt to your subject’s color to get the best peaking contrast. How to get better focus results The key to getting critical focus is to use viewfinder/rear screen magnification. You magnify the viewfinder by using the little “magnifying glass +” button on the back of the camera. Multiple presses of this button will give greater viewfinder image magnification. No screen/viewfinder magnification The shot above shows the camera rear screen at NO magnification (it was too difficult to get a photo of the viewfinder view). The peaking sensitivity was set to “1 (low sensitivity)”. Even at the 1 setting, the “in focus” peaking is too sloppy and covers most of the frame. Single-press of the “Magnifier +” button Notice that the slightly-magnified screen view has significantly reduced the range of the red peaking display. This is a much better indicator of what is really in good focus. Double-press of the “Magnifier +” button At higher viewfinder magnification, the range of “in focus” is much narrower. By the way, notice how none of the nearly-horizontal edge detail is shown as “in focus” although it is clearly in focus. Triple-press of the “Magnifier +” button Bummer! At this very high screen magnification, there are NO focus peaking indicators. What to do? Again, the shots above are all using the “1 (low sensitivity)” setting. Triple-press of the “Magnifier +” button, ‘standard’ sensitivity I switched over to the “2 (standard)” peaking sensitivity. At the same high viewfinder magnification, peaking has returned! This setting is pretty sloppy at zero viewfinder magnification, but at high viewfinder magnification it is really good. Horizontal edge detail No peaking to be seen for horizontal edges Note the total absence of horizontal-edge peaking indicators. The reason for this is how Nikon implemented focus-peaking in their firmware. The camera is only looking at left/right pixel neighbors for changes in illumination level. If you’re looking at a subject made up of only horizontal detail, then you’ll need to briefly roll your camera about the lens axis to confirm focus. Focus-peaking math If you’re interested, here is a little discussion of how the low-level camera firmware operates to figure out focus-peaking. Don't freak out about the math. First, the camera makes up little lists of a pixel with its left-right nearest pixel neighbors. These lists consist of a pixel number and its illumination level. Next, these lists are run through a ‘linear regression’ to calculate an equation that best fits a line through the plot of pixel-number versus pixel-illumination. The equation of a line in most math books looks like this: Y = m*X + b The Y shown above represents pixel illumination. The m above is the ‘slope’ of the line, where a bigger (absolute) slope value is steeper. The X is the pixel number. The b is where the line crosses the vertical (Y) axis. When the line slope of pixel/illumination reaches a critical value, it means that the camera found a large-enough brightness change to indicate an in-focus edge and activates focus-peaking at this pixel. This process is repeated all around the image sensor, using a bunch of little lines. The camera menu peaking sensitivity is then related to each of these tiny rows of pixels. For high sensitivity, it activates peaking with fairly low slope values. For low sensitivity, it demands a high slope value. Sample of a line with low illumination changes Above, I show some made-up data of a short horizontal row of pixels somewhere on the sensor. I used pixel 900 through 910 (out of over 45 million pixels!). The brightness at these pixels ranges from ‘50’ to ‘94’ units. Using Microsoft Excel, I performed a linear regression on the data to calculate the equation of a line that best fits this data. The plot shows the original data (blue) and the best-fit line (red). The calculated slope of this line is “4.6”, which is fairly low. It would take a “high-sensitivity” focus peaking setting to decide that this represents an in-focus edge, and displays it in the viewfinder. If I had set the focus peaking to “low-sensitivity”, then this low slope value wouldn’t trigger any peaking to be displayed at this location in the viewfinder. A ‘high-sensitivity’ setting, however, would trigger peaking in the display, because it is sensitive to even small slopes. Sample of a line with large illumination changes Using my fake data above, the line was calculated to have a slope of “17.5” or so. This is a much steeper line (and higher slope value). Focus peaking would get triggered at ‘low sensitivity’ for a steep slope like this line has, as well as ‘high sensitivity’. This portion of the viewfinder would probably show peaking at any sensitivity setting. Nikon could have chosen to do the same peaking scheme using vertical columns of pixels, but decided not to do so. Most of the time, that decision has proven to be just fine. Summary I hope that gives you a better insight into what focus-peaking is, and how to use it to the best advantage. Stick with the lowest sensitivity that you can, and use the highest viewfinder magnification that you can to get the sharpest focus. Focus peaking makes using manual-focus lenses better than in any other time in history, especially when combined with the mirrorless camera viewfinders that allow magnification.