I was comparing a DSLR (the D850) against a mirrorless Nikon Z8 using the same lens. After careful autofocus fine-tune adjustments, I was able to improve the focus results for the D850 camera. Since both cameras have the same sensor resolution, the Z8 (or Z9) should be able to achieve at least the equivalent focus accuracy (e.g. equal lens resolution measurements) of the D850.   I have never messed with the autofocus fine-tune feature on either my Z8 or Z9. I have read that it’s completely unnecessary, and until now I had believed this narrative. It now seemed like an appropriate time to go there. All of the testing and measurement associated with focus calibration isn’t exactly enjoyable, but there’s no way I was going to let my D850 beat my Z8 or Z9 without a fight.   I should mention that I used AF-C with 3D-tracking focus on both cameras. This is my favorite focus mode, so it’s how I like to test my lenses for real-world resolution results. The best way to determine the highest resolution a lens can get is to forget focusing the lens entirely, and instead move the camera/lens combination on an adjustable rail in small (sub-millimeter) amounts between test shots. But that's not how photographers actually shoot. Focus Fine-tune in the Nikon Z8 Setup Menu   By default, the Nikon Z camera autofocus fine-tuning is turned off. The fine-tuning features are located in the Setup  menu. AF fine-tuning menu   To adjust the (attached) lens, scroll down to the “ Fine-tune and save lens ” option. Set the desired setting   As shown above, I set the 500mm f/5.6 PF fine-tune value to -2 , which will then force the lens to focus slightly nearer to the camera. Press “ OK ” to save the new setting. The Nikon D850 resolution testing results   As shown above, my Nikon D850 was focus fine-tuned to -2 when I conducted focus testing. Many of the resolution readings hovered around MTF50 80 lp/mm for the center of this Nikkor 500mm f/5.6 PF lens. This was the best that I was able to get out of that camera/lens combination. I use the free MTFMapper program to measure lens resolution.   By the way, the horizontal axis values above are just the frame number of each shot.   The data plotted above had an average MTF50 resolution of 71.7 lp/mm, with a peak of 84.8 lp/mm and a standard deviation of 10.3.  Notice that many of the resolution readings hovered around 80 lp/mm.   There’s a huge spread of resolution results, which means that the camera was quite variable in how it focused on the resolution target. This is unfortunately completely normal for a DSLR using phase-detect focus. This spread (variation) of resolution results is reflected in the standard deviation value of 10.3. The Nikon Z8 resolution testing results   My Nikon Z8 testing results (with NO AF-tune adjustments) are shown above. Their consistency is superior to the D850, but many of the resolution readings seem a bit lower than what the D850 had occasionally achieved.   The Z8 resolution testing results had an average MTF50 resolution of 74, with a peak of 98.2 and a standard deviation of 6.7.    While the Z8 on average  got better resolution than the D850, it looked like there was room for improvement. I tried various AF-tune values on the Z8, and it turns out that the same  AF-tune value of -2 got the best results out of this lens. Normally, different cameras will have very different fine-tune settings with the same lens. The Nikon Z8 resolution testing results with AF tune -2   The resolution results from the data plotted above got an average MTF50 resolution of 77.1. The peak reading was 84.1, with a standard deviation of 5.3.   Although not huge, the lens resolution increased from an average of 74 to 77.1 lp/mm after implementing the fine-tune compensation.   Note that the D850 standard deviation was 10.3, while the Nikon Z8 standard deviation was 5.3.  This demonstrates significantly less focus variation with the mirrorless camera.   A word of caution is in order. Don’t  use ‘pinpoint’ or ‘starlight’ focus mode when investigating autofocus fine-tune. These two modes use contrast-detect instead of phase-detect, and therefore ignore the fine-tune calibration. If your target is quite small, you might want to use the single-point focus mode, which is very selective and still uses phase-detect and allows AF-C focus.   Another caution: if you’re using F-mount lenses and you have more than one FTZ adapter, you’ll have to pay attention to which adapter is in use. Teleconverters can also mess up the fine-tune calibration.   The Nyquist Limit   According to Edmund Optics , the absolute limiting resolution of a sensor is the Nyquist Limit which is half of the sampling frequency (pixels/mm). For the Nikon Z9/Z8, for instance, the Nyquist limit is (8280/35.9)/2 pixels per millimeter (231/2 pix/mm) horizontal or (5520/23.9)/2 pixels/mm vertical, or again (231/2) pix/mm.    The Nyquist limit of (231/2) lp/mm is then 115.5 lp/mm.    The typical actual frequency response includes what’s called the “Kell Factor” named after Raymond Kell, which is conservatively set to 0.7.  This value helps compensate for the physical space between the light-sensitive portions of the pixels, and to avoid patterns similar to the moire effect. This means the practical actual sensor frequency response limit is now (115.5 * 0.7) or 80.85 lp/mm.     Given this information, any measured resolution above 80.85 lp/mm is unreliable. In any event, the Z8 average of 77.1 lp/mm with this 500mm f/5.6 PF Nikkor is darned near the Nyquist limit.     Summary   It turns out that Nikon included the AF-tune feature in their Z cameras for good reason. It’s not useless and ignorable after all. I was able to squeeze out a little bit better focus accuracy (and resolution) from my lens. The resolution increase was only about 4 percent, but I’ll take it.   The Nikon Z8 won the focus fight over the D850 after all. It’s no longer feeling embarrassed by the D850.

I have read on several occasions that you should always turn off IBIS ( i n- b ody i mage s tabilization) when you use a tripod. I’m such a terminal skeptic that I decided to try it for myself.   For my tests, I decided to pick on my Nikon Z9 and the 24-120 f/4 S Nikkor lens at 120mm and f/4. This lens doesn’t have any internal vibration reduction, and instead it entirely relies on the camera IBIS system.   I used a wired remote release and my heaviest tripod and on top of a concrete/porcelain tile floor indoors, so that any other kind of vibrations should be minimal. I got about 3 meters from my target, which is the edge of a tiny razor blade.   I picked a fairly slow (1/30 second) shutter speed, which should in theory readily show image motion (if there is any).   The Nikon Z9 (and Z8) have pure electronic shutters, plus they focus at the shooting aperture (through f/5.6). This means that these tests won’t be affected at all by ‘shutter-shock’ or moving aperture blades.   I used my MTFMapper program to evaluate the image resolution, which is much, much more sensitive than the naked eye in seeing any sharpness loss from vibrations.   I should mention that the orientation of the edge being evaluated will change the measured resolution. Every combination of sagittal and meridional direction will give a different result, which is big reason why it’s impossible to give a single-number answer to overall lens resolution.   I re-focused the lens (AF-S mode) using pinpoint focus mode in between each shot. This means that there should be a small variation in resolution between each test shot, due to the focus distance natural variation.   The target (edge) was far enough away that I did my measurements on just a 226-pixel portion of the razor blade. The whole point in this setup was to give the IBIS system the maximum chance to mess up the sharpness. Extreme crop of frame showing the target selection (in cyan) The whole frame Spreadsheet of resolution results     Taking 20 shots with and then without camera IBIS active, I plotted the resolution results and got the average and standard deviation of the MTF50 resolution, in lp/mm units.   The average resolution using IBIS was 95.5 lp/mm. With IBIS turned off, the average was 94.1 lp/mm. The data spread (standard deviation) for active IBIS was 1.82 versus 2.55 without IBIS.   In other words, there’s hardly any difference when using IBIS or not, when mounted on the tripod. If anything, there is a slight improvement using IBIS. This is the exact opposite of what I’ve been reading on the internet.   It’s possible, of course, that the effect of using IBIS might be highly dependent upon which camera model you use. I only know that my Nikon Z9 and Z8 cameras use the exact same IBIS system.   Since it’s a pain to mess with switching IBIS on/off in different situations, I’m glad to know that you needn’t bother with turning IBIS off when mounting these cameras to a tripod.

The highest frequency you can accurately capture in a photo is called the Nyquist frequency, no matter how good your lens is. If you take a picture of finely-spaced details that are smaller than twice your camera sensor’s pixel spacing, you’ll get that ugly aliasing. In other words, your sensor needs at least two pixels across for every skinny line in a light-dark pattern to properly record them.   Aliasing is often called ‘false detail’. With this defect, you can get weird color rainbows where none exist and also light/dark patterns where there shouldn’t be any.   In the past, the only way to get rid of aliasing was to either buy a camera with more pixels or to fuzz-out the image using a camera that had an anti-aliasing sensor filter. Neither option is very good, unless you have plenty of disposable income for that huge medium-format camera.   Several camera companies, now including Nikon, let you perform pixel-shift shooting. With this technology, your camera can rapidly move (shift) your camera sensor by typically half or a full pixel width both horizontally and vertically. After moving the sensor, the camera takes another photo and then repeats the process with each neighboring pixel. After the fact, you can use an editor to combine these shots into a single photograph that has effectively more pixels in it.   If you haven’t already figured it out, this means that you can’t use pixel-shift shooting for moving targets.   The Nikon Z8 (plus the Nikon Zf and Z6III) support pixel-shift shooting. You can take 4,8,16 or 32 shots and then combine them using Nikon’s NX Studio .  I made an article about how this process works located here .    You can now get pictures with up to 16512 X 11008 pixels, or 181MP , if you choose the 16 or 32-shot options. I noted that the combined shots are 912MB (in NEFX form). I shoot in the raw ‘HE’ format, to get smaller raw files. When I used the free Adobe DNG Converter, these shots were reduced to 559MB. Still huge.   Everybody talks about the pixel-shift shooting benefits of higher resolution and image noise reduction, but the ability to reduce or eliminate aliasing has been largely ignored. 70mm 1/320s f/4 ISO 5000, 200% zoom view, single shot   The shot above was taken from the 1st capture out of the 32-shot sequence that created a pixel-shifted picture. I shot at a distance that clearly shows aliasing (see the barcode above). It’s easy to see the blue and orange colors inside the barcode that didn’t exist in real life. The screen capture here is at 200% zoom from a much larger image.   As an aside, note that there’s a fair amount of image noise and much of the text is illegible. I did a 32-shot pixel-shift sequence to show the limits of what this camera could do to rid noise, increase resolution, and of course attempt to rid aliasing. 70mm 1/320s f/4 ISO 5000, 100% zoom view, merged 32-shot   The merged 32 pixel-shifted shots make a world of difference. Besides the obvious resolution increase and image noise elimination, note that the barcode was transformed from false orange/blue mush into distinct lines. Horrible aliasing and noise, single shot NO aliasing and no noise, 32-shot pixel-shift merge.   As seen above, the standard Nikon Z8 sensor resolution resulted in a shot where black lines in the barcode were replaced by fake orange and blue rainbows. This effect can really make some fabrics look horrific, too.   All of the shots shown were processed in Capture One 2023  with no sharpening or noise reduction. If I were to process the merged shot with my Topaz DeNoise AI , it could be made even sharper than what you see here.   I used my Sigma Sports 70-200 f/2.8 zoom for all of the shots in this article. This is a really sharp lens, and it’s obviously capable of producing much higher resolution than my Z8 sensor can use. If you notice that your photographs have aliasing in them, it’s a dead giveaway that your lens resolution is better than your camera sensor.   As you can see, going from a sensor with 5520 X 8280 pixels to an effective sensor with 11008 X 16512 pixels is an enormous jump in quality that has to be seen to be appreciated. It’s just a shame that you can’t do this with action shots.   While it’s impossible to rid aliasing in all situations, this technique will get rid of it for the vast majority of cases.   I’m still waiting somewhat impatiently for this feature to show up on my Nikon Z9 with the next firmware update…

When you shoot multiple shots to stitch into a panorama, you should pivot the lens around what’s often called the entrance pupil . This magical pivot spot is the only  location that will eliminate parallax error. This spot is also known as the nodal point .   If you don’t pivot your lens in the correct location, you’ll end up with overlapping shots that don’t match up precisely. Stitching programs try to compensate for this error, but it’s better to get the right shots in the first place.   Unfortunately, lens manufacturers don’t normally provide the information about the lens’ entrance pupil. In this case, you’ll probably have to figure it out for yourself. Believe it or not, sometimes the entrance pupil can be located outside  of your lens.   To set up a lens for proper panorama shooting, you’ll need a tripod head that can rotate about the vertical axis, and you’ll also probably need an attachment plate that you use to offset the camera tripod screw from the tripod’s pivot axis. The best attachment plates are Arca-Swiss (your tripod head needs to have an Arca-Swiss clamp). With these plates, you can easily slide the camera/lens and then securely clamp them in place.   There are also special ‘panorama heads’ you can buy to make panoramas, instead of the more generic Arca-Swiss clamps. You still need to locate the pivot-point(s) for your lens to make proper use of them, however. Beware that zoom lenses have a different pivot point for each focal length. Camera attached to a long Arca-Swiss plate   In the photo above, the camera is attached to a long Arca-Swiss plate on top of a tripod. The long plate allows the camera to be shifted far from the tripod rotation centerline. Now, when the tripod head gets rotated the camera/lens will rotate around the vertical red line instead of the camera tripod socket.   Usually, really long Arca-Swiss plates are a pain and are best avoided. Here’s a case, however, where a long plate is exactly what’s needed. As you’ll see below, sometimes even the hardware shown above isn’t enough to achieve a correct pivot.   Method 1 to Locate Pivot Location   To gather the information about the ideal pivot location, you need to start by taking photos with subjects at medium and long distances that are aligned with each other. Start by aligning the near and far objects in the exact frame center. Your camera should be perfectly level. Now, rotate the tripod head to get those objects on the left-hand side of the frame. Take a shot with the distant detail on the left frame edge and then rotate on the tripod to the right edge of the frame and take another photo.   Repeat the process, but first shift the camera/lens combination in the tripod’s Arca-Swiss clamp by a large amount. Make notes about which shift location was used for each pair of shots.   With a mirrorless camera, you might get away with just switching to a magnified view to check for left/right alignment and skip having to review photos. The first attempt: pivot around the camera tripod socket   I used an 8-meter-away window frame for the medium object, and a 500-meter-away palm tree for the distant object. I adjusted the camera position until the medium and far objects were right next to each other in the exact frame center.   Next, I pivoted the camera to place those objects on the left side of the frame. I captured the first shot. Close object aligned with distant detail on the frame left edge Distant detail appears shifted right  from the window frame       Next, I pivoted the camera to place those objects on the right side of the frame and took another shot. Close object aligned with distant detail on the frame right edge Distant detail appears shifted left  from the window frame   The results from pivoting over the camera’s tripod socket were terrible. The distant object shifted severely, compared to the window frame. It slid from one side of the window to the other, just by photographing it from opposite sides of the frame.   What’s shown above is classic parallax error. The distant object keeps moving, relative to a closer object, when shot from different left-right locations in the frame. The next test: pivot around the lens as shown     Since I am using a mirrorless camera for the testing, it’s pretty straightforward to just iterate as follows, once I have my near/far objects aligned in the frame center using a magnified viewfinder image:   1)    Pan left or right and observe any shifting of the far object. 2)   Slide the camera/lens forward or backward in the Arca-Swiss clamp by maybe 10mm and lock it down. 3)   Repeat the panning to see if the far object shifting error grows or shrinks. If it is growing, then slide the opposite direction in the clamp. Go to step (1).   In my testing, the trends indicated that moving the pivot point more toward the lens front got better and better results. Finally, I ended up with the configuration shown above. The entrance pupil is roughly between 90 and 100mm from the camera sensor at the 24mm focal length. I couldn’t tell the difference after I got to within a zone of maybe 5mm at this focal length. Close object aligned with distant detail on the frame left Distant left-detail appears the same as in the frame center!   Close object aligned with distant detail on the frame right Distant right-detail location matches the frame center and left!     After I located the proper lens pivot location, I attached the Arca-Swiss plate onto the camera such that one end of the plate exactly aligned with the Arca-Swiss tripod clamp edge. This makes it easy to reliably place the camera onto the tripod with perfect alignment for correct panorama pivots.   I got lucky with this 150mm Arca-Swiss plate. If it were any shorter, then I wouldn’t be able to quite reach the lens nodal point with the plate fully gripped inside the tripod head’s clamp.   The top photograph shows the correct nodal point (entrance pupil) for the Nikkor 24-120mm f/4 S lens when zoomed to 24mm. Same lens zoomed to 120mm: entrance pupil now located at 59.5mm I got my smug smile wiped right off of my mouth when I now tried zooming the lens from 24mm out to 120mm. Big-time parallax error had returned. After repeating the panning procedures at this zoom setting, the new nodal point was located as shown above. Method 2 to Locate Pivot Location   The following technique can at least get you close to finding the lens nodal point (entrance pupil). This technique is more challenging and time-consuming than the first method.   You need to draw the lens horizontal field of view (FOV) angle on paper, with a line splitting that angle exactly in half. In the case of this 24mm setting, that’s 73.7 degrees, with the split line at 36.84 degrees. Use a protractor to measure the angle. Lay this paper on the floor and lay some long straight guides along these lines. You might find that using string taped to the floor will make a good guide line. Mark the exact field of view angle and lay guides     Next, place your camera on the floor over the intersection of these guides, and shift it forward and backward until both guides are seen just along the vertical frame edges in the viewfinder. Switching to Live View may make this job easier. Be sure to stop down the lens aperture to get a deep depth of focus.   Also, you’ll want your camera to be level. I have a handy little bubble level that I keep in the camera’s hot shoe to check for level. Align the camera to split the angle Slide the camera to get the guides parallel to frame edges   Notice that the thin black guide lines are just along the frame edges in the shot above. Where the guides intersect under the camera/lens is the location of the correct pivot point (entrance pupil).   To verify the pivot point, go back to Method 1 using this location as a starting point to see if it's correct. You may need to fine-tune the location a little. 15-frame panorama after pivoting around the ‘entrance pupil’   I stitched the photographs together using Capture One  with ‘cylindrical projection’. This editor has several projection options. I like using Lightroom  for making panoramas, too. Nikkor AF-S 24-70 f/2.8 E ED VR at 24mm zoom setting     Shown above is another lens also zoomed to 24mm. Its entrance pupil is quite different than the 24-120mm lens. It should be obvious that the kind of severe offset of the camera and the center of gravity shown above requires a very sturdy tripod. The last thing you want is to have your tripod fall over with your camera and lens.     Entrance Pupil the Easy Way If he happens to include your lens, Bill Claff’s Photons to Photos database of lens information has already compiled the pivot information you need. Bill’s wonderful site has many lenses analyzed here, and you need to find the value of ‘P’  (entrance pupil) and ‘ I ’ (image plane) for your lens at the correct zoom setting. For the 24-70 lens shown above, his site link gives the values of P=34.76mm  and I=220.25mm at 24mm.  Just do the subtraction  I-P or  (220.25 – 34.76)= 185.5mm  to find the distance from the camera sensor to the tripod pivot location. At 50mm zoom, the pivot is at 181.25mm , and at 70mm zoom, the pivot is at 172.3mm .   These pivot numbers are pretty huge, requiring hardware with a long range of adjustment. This also requires strong tripod hardware.   I found out that Bill had also analyzed my 24-120 f/4S lens, unfortunately only after  I did the experiments mentioned above, and I got essentially the same results as Bill did. Bill got I@24mm = 130.96mm, P@24mm = 30.8 and I@120mm = 185.96mm and P@120mm = 126.43mm. This means the sensor-to-pivot at 24mm = 100.16mm. For the 120mm zoom setting, this means the sensor-to-pivot value is 59.5mm .   Bill has my 24-120mm lens listed as “Nikon 25-117mm f/4 IF”, which is why I didn’t find it at his site initially. He lists it according to the measured focal length versus the actual lens name.   Bill has lots of very nice information on his website, although much of the site is targeted more for scientist types.   Summary   Probably 99% of photographers would simply use the camera tripod socket location on their tripod for making panoramas. As demonstrated above, that would simply produce incorrect results. Don’t be that photographer; you’re better than that.    The procedures shown above could also be done with the camera in portrait orientation, but you better be sure that you have pretty heavy-duty hardware, a camera ‘L’ bracket, and a strong tripod.

I thought it would be interesting to show you how to find out (or verify) your lens’ focal length and its field of view.   One reason you might like to measure this stuff, versus just reading the lens focal length stamped on the lens, is that manufacturers often lie about the true lens focal length. This is particularly true of long zooms, which might not be as long as claimed. It’s often the case that a lens focal length reduces drastically when focusing close (called focus breathing), and these techniques could attach real numbers to that.   The diagrams above show the setup to align and measure your lens to get the information for calculating the focal length and field of view ( FOV ).   You only need to take 6 different measurements to calculate everything! The trick is in setting up the targets to make those measurements accurate.   The mathematics used in the calculations involves both algebra and trigonometry. Any “scientific” calculator has the necessary features to do this math. You can always download a scientific calculator app onto your smartphone. Fear not the math.   To get all of the necessary information, you’ll need to set up some targets on a wall (I used painter’s tape) and then take distance measurements at two different camera-to-wall distances. Carefully place tape at center and edges of the field of view   As shown above, I put some tape targets on the wall that point at the edges of the field of view and the exact center of the frame. I made sure that the distances on either side of the middle of the frame exactly matched. I also made sure that the lens was at exactly the same height as the middle wall target. Using high magnification via Live View or the viewfinder helps getting the targets more precise.   My setup was on a tile floor, and I used the tile grout lines to make sure the lens axis was exactly perpendicular to the wall. You could also temporarily tape a little mirror against the wall and line up the camera until you see your reflection in the center of the camera’s field of view. Laser for even better measurements   I happen to have a fun little laser that can make extremely accurate measurements over long distances. I used this device to get my targets placed within a millimeter, and to measure the camera-to-subject distance.   As I often say, “garbage in, garbage out”. The more accurate measurements you make, the more accurate your results will be.   I made all of the distance measurements relative to the lens axis and to a spot on the lens that I guessed to be near the vertex of the red arrows shown in the diagram. You don’t really need to know this location, since these techniques will actually calculate the location.   The nearer wall distance setup is called ‘ x ’. The farther wall distance setup is called ‘ X ’. Similarly, the distance along the wall from the frame middle to the frame edge in the nearer wall setup is called ‘ y ’, while the farther distance setup is called ‘ Y ’.   For both setups, the angular measurement from the lens axis to the frame edge is called ‘ Angle ’, measured in degrees. The FOV  of the lens is twice the value of ‘Angle’.   k  = Error Distance from lens measurement location to the true angle vertex.   k = ((y * X) – (x * Y)) / (Y – y)   x  = near_wall_distance from lens measurement location X  = far_wall_distance from lens measurement location   y  = (near_view_width) / 2 Y  = (far_view_width) / 2   Angle  = FOV / 2   Angle = ArcTangent (y/x)   x = y / Tangent(Angle)         and   X = Y/Tangent(Angle)   y = Tangent(Angle) * x         and   Y = Tangent(Angle) * X   FOV  = 2 * ArcTangent(y/x)  and FOV = 2 * ArcTangent(Y/X)   x_Actual  = x + k                   X_Actual  = X + k   Focal_length = (sensor_width * x_Actual) / (y * 2)       Example   I used my Nikkor 24-120mm f/4 S zoom at the 24mm position.   x = 1306mm y = 1085.85mm X = 2141mm Y = 1711.325mm   k = ((y * X) – (x * Y)) / (Y – y) k = ((1085.85 * 2141)-(1306 * 1711.325))/(1711.325 – 1085.85) k = 143.594mm   FOV  = 2 * ArcTangent(y/x)  FOV near = 2 * ArcTangent(1085.85/1306) = 79.48 degrees   FOV far = 2 * ArcTangent(1711.325/2141) = 77.27 degrees   x_Actual  = x + k x_Actual = 1306+143.594 = 1449.59mm   X_Actual = 2141+143.594 = 2284.59 mm   FOV_Actual = 2 * ArcTangent(1085.85/1449.59) = 73.67 degrees   Focal_length = (sensor_width * x_Actual) / (y * 2) Focal_length = (36 * 1449.59) / (1085.5 * 2) = 24.03mm   My angle vertex ‘guess’ at the front of the lens wasn’t very close. I had a calculated error of about 144mm.   It just so happens that the horizontal field of view of 73.7 degrees is what a 24mm lens has with a full-frame camera!   Summary   Using these techniques, you could actually find out what an un-marked lens’ focal length is. You could also verify (or debunk) manufacturer claims about the real focal length of a lens.

It’s in Nikon’s documentation that you can only use Pinpoint AF  while in the AF-S  focus mode. It turns out that even in this AF-S mode that you’re not allowed to select Pinpoint focus when you have assigned the “ Cycle AF-area mode ” to a button. I’m talking about assigning a button inside the Custom controls (shooting)  menu option.   I’m using the Nikon Z9 firmware version 5.0 the Z8 2.01 version. I just noticed this bug, but I assume it’s also a problem with older firmware.   If, instead, you go to the Photo Shooting Menu  and select Pinpoint AF inside the AF-area mode  there, you’ll be able to enable Pinpoint focus (assuming you are using Single-AF focus mode).   When I tried pressing the Sub-selector center button, it would cycle right past Pinpoint and invoke all of the other requested AF-area modes that are legal while in AF-S focus mode. 3D-tracking, for instance, isn’t allowed while in AF-S focus mode. Set Pinpoint AF here Custom controls (shooting) button assignment Assign Cycle AF-area mode Pinpoint AF gets ignored!! Pinpoint focus indicator   I hope that Nikon will eventually fix this bug.

I have known since the first day I got my Nikon Z9 that it focused better than any Nikon DSLR I have ever owned. When I got the Nikon Z8, I noted that it seems to focus exactly like the Z9.   I was a long-time holdout against mirrorless cameras, both because of their short battery life and their sluggish viewfinders. I didn’t see any particular advantage over DSLRs to persuade me to stop using my D850 or D500. Nikon eventually solved all of the mirrorless shortcomings that I knew about, and then some. I didn’t know just how much they had improved the focus system compared to DSLRs.   Instead of just ‘feeling’ like they focus more consistently, I did some tests to get some actual numbers comparing one of my mirrorless Nikons (the Z8) against my best DSLR: the Nikon D850. The camera sensors have the same resolution, so any measurements can be compared directly.   To eliminate any doubts about the lens being a limiting factor, I decided to use my 500mm f/5.6 PF Nikkor, which I consider my best lens, for the tests. Both cameras used the same ISO and exposure. I used a wired shutter release, and the D850 shots were done in “mirror-up” mode.  I manually de-focused the 500mm lens between each test shot, to force the cameras to do a full re-focus using AF-C.   My benchmark to evaluate focus accuracy is the lens resolution measurement, since higher resolution measurements correlate perfectly with accurate focus. I used a precision razor blade edge as my focus target, since it always gives me either equivalent or superior resolution measurements compared to my printed targets. I use the MTFMapper  program to evaluate my focus target photos.   I tested both cameras using phase-detect 3D focus. I’m not interested in comparing slow contrast-detect focus, even if it might be more accurate. My D850 has been autofocus fine-tuned with the 500mm lens; my Z cameras don’t seem to need this crutch, although they include that option in their menus.   I took many raw-format photos of a precision razor blade that is in silhouette. I don’t want to use any automatic sharpening (such as when shooting jpeg) to affect the resolution measurements. The camera/lens is on a heavy support, so that each shot has the blade silhouette in exactly the same location. Make sure that the razor blade is perfectly parallel to the camera sensor. Mirrorless Z8 versus DSLR D850 The focus subject is a slanted high-precision edge   The shot above shows the MTFMapper  dialog used to perform “manual edge selection”. I have a razor blade with strong back-lighting as a target, and I put the camera focus point over the center of the razor’s sharpened edge. After using the computer mouse to select the portion of the blade image to use, I let the MTFMapper  evaluate this edge to determine the lens resolution at this position and orientation.   The MTFMapper  program lets me select all of the test photos at once; it assumes the target in each shot is at exactly the same position. I make sure that “ reuse ROIs ” is selected, and then click the “ Accept Queued ” button to have the program evaluate all of the photos without further intervention by me. A typical shot after MTFMapper  has finished evaluation   You can see a little cyan-colored MTF50 resolution measurement superimposed over the location on the blade where I requested the program to evaluate the resolution. In this shot, the MTF50 resolution measurement is 84.8 lp/mm.   I put all of the measurement results from MTFMapper  into an Excel  spreadsheet. I then plotted the resolution measurements against the camera filename (frame number). D850 resolution variation with 500mm f/5.6 PF, AF_tune -4   The plot above shows the variation in resolution measurements for the Nikon D850. Again, I de-focused the 500mm lens and then refocused between each shot, to force the camera to perform a new phase-detect, AF-C focus in 3D-tracking mode.   The D850 results got an average MTF50 resolution of 63.2 lp/mm , with a peak reading of 81 lp/mm  and the standard deviation (spread of measurements) was 8.12 .   Since there was a single measurement higher than the others, the autofocus fine-tune setting could possibly be re-adjusted to get overall better focus, although the photo EXIF data in every frame indicates the same 4.47m focus distance. The spread  of the measurements isn’t affected by the autofocus fine-tune setting.   Bear in mind that resolutions above 40 lp/mm will all appear pretty sharp, so these results are still good. Nonetheless, I decided to change the AF-tune and re-try the shots. D850 resolution variation with 500mm f/5.6 PF, AF_tune -2   The D850 with the new AF-tune -2 results got an average MTF50 resolution of 71.7 lp/mm , with a peak reading of 84.8 lp/mm  and the standard deviation (spread of measurements) was 10.3 .   The slight AF-tune adjustment change definitely helped! Notice that there is sort of a split in the data. When I was shooting the target, I would de-focus the lens by alternating too near and then too far shot-to-shot. The camera seems to have a bias in focusing based upon the direction to achieve focus.   I don’t know if something might have shifted or drifted over time with the focus calibration. It was definitely worth re-checking this, since it resulted in a typical gain of about 13 percent resolution. Z8 resolution variation using 500mm f/5.6 PF   The plot above shows the variation in resolution measurements for the Nikon Z8. Again, I de-focused the 500mm lens and then refocused between each shot, to force the camera to perform a new phase-detect, AF-C focus in 3D mode.   The Z8 results got an average MTF50 resolution of 74.0 lp/mm , with a peak reading of 98.2 lp/mm  and the standard deviation (spread of measurements) was 6.7 .  With the exception of the single reading of 98.2, the data was much more tightly grouped than the D850 results. I think that the 98.2 reading is some kind of a fluke which should probably be ignored.   If you’re interested, the average resolution of 74 lp/mm is equivalent to 3537 lines per picture height. I prefer using ‘lp/mm’ units, since it applies to any size sensor.   I didn’t notice any bias in resolution related to focusing from near-to-far versus far-to-near, either. The Z8 (and Z9) are just smarter about focus.     Summary   The Nikon Z8 (along with its big brother the Z9) has noticeably better focus consistency than the D850. After seeing how the D850 results dramatically improved with such a small AF-tune adjustment, I should probably explore using that option on my Z cameras, too.   Before testing with my Z8/Z9 cameras, I would have said that my Nikkor 500mm f/5.6 PF lens had a typical center resolution of about 63  lp/mm when using 3D continuous autofocus on my D850. After studying those results and modifying the autofocus fine-tune, I changed my mind to conclude that the resolution was closer to 71  lp/mm. Now, I can say that it has a typical center resolution of roughly 74  lp/mm when using 3D continuous autofocus on the Z8/Z9 cameras.   If you only shoot using slow contrast-detect focus (via Live View on the D850) then these focus (resolution) differences will largely disappear. If your lens has focus-shift issues when changing the aperture, then the focus variation differences between DSLRs and mirrorless cameras will increase . The Nikon mirrorless cameras focus at the shooting aperture when using phase-detect (through f/5.6), but the DSLRs don’t.   You need to shoot many tests and study those results to guide yourself toward optimal calibration, in the case of DSLRs. Statistics exist for a reason; you can’t really know how your gear performs without doing lots of testing. It’s possible that your mirrorless Nikon could squeeze a bit more sharpness out of a lens with autofocus fine-tuning, as well.   Mirrorless definitely wins the war of consistency over DSLRs when using phase-detect focus.

I originally purchased ON1 Photo Raw  to get the ability to easily substitute interesting skies for boring skies in landscapes. Besides just using the sky images included in the ON1 installation , the editor lets you easily add your own skies.   Another great way to make photos much more interesting is to include the Moon in them. If you have ever worked on planning shots to include the Moon, you appreciate how difficult it can be to achieve. Being in the right place at the right time is rare, and those clouds can still move in to ruin your best laid plans. Is it real?     If you use a really big lens for moon/landscape shots, you’re well aware of how it’s typically impossible to get the foreground and the moon both in focus. If the moon is low in the horizon, then atmospheric effects ruin the sharpness.   Your substitute ‘sky’ can just as easily include the Moon. In this case, you could shoot photos of the Moon with a longer focal length and also take the shots when it’s high in the sky to get better details. It’s also a good idea to take both landscape and portrait-orientation shots for more options while editing later.   The ON1  editor is pretty good at masking complicated images, which allows you to even have tree branches partially blocking the Moon.   Have you ever taken landscape shots with wide-angle lenses, but you wanted to have the Moon appear larger in those shots? With substitute Moon/sky shots, now you can finally combine wide-angle landscapes with a large moon in them!   I should mention an old article I wrote that gives you the details on how to add your own custom skies to the ON1  editor. If you don’t know how to do this operation, then this article  should help. A Moonset shot that never really happened     Notice in the shot above that the Moon is partly hidden by tree branches. The ON1  editor is capable of pretty sophisticated masking. Inside the ON1  editor   The screen image above shows how I adjusted the sliders to control how a Moon shot was combined with a landscape. The landscape here was shot at 32mm, while the moon was shot using a long telephoto.   Once I find the desired Moon ‘sky’ and add it where I want it, I can then go over to the ON1   Develop tab to edit the shot further. A typical Moon shot to add to the ON1  editor   I have many Moon images added to my ON1  editor in its sky-swapping feature. I took my Moon shots while the Moon was high in the sky, so that I got rid of most atmospheric sharpness-killing effects.   There are several controls in the ON1  editor Sky  feature that let you have some control over where the Moon gets placed. This way, you don’t have to add too many shots into your ‘custom sky’ library. These controls include Position (left-right flip), Shift Horizon (vertical shifting), Level  (small horizontal/vertical movements), and Magnify (size change). The Moon adds a little spice to this harbor shot How the Moon’s reflection got added   For a more enhanced realism, the ON1  editor even lets you add a reflection if you want. I tend to prefer this particular shot without a reflection, but with this feature you get to explore adding a reflection or not. Don’t go there     Please avoid getting too outrageous with big moons, just because you can.  I suppose you could be working on some sci-fi assignment…     Summary   I know many photographers cringe at the thought of altering their shots in any way. If that’s your personality, then this technique is certainly not for you.   The ON1  editor has lots of fun and creative features in it, and using its sky-swapping capability to add the Moon can really make some blah shots a bit more interesting.

If you’re interested in seeing how sharp your camera lens is, but you don’t have a test chart to use, read on.  The free program MTFMapper has a feature called “Open with manual edge selection”. Using this program option, you’re given the freedom to select anything in a photograph and potentially use it to measure your lens resolution. The excellent MTFMapper program is authored by Frans van den Bergh, and can be downloaded from this site. MTFMapper has been used by NASA to measure lenses that are now in use on the planet Mars. There are rules (as always) for what you can use as subjects for testing lens resolution. For instance, you need a dark, straight, slanted edge against a light featureless background. The straight edges are preferably black, but if you have a strong backlight to get a silhouette effect, then the object with the edges doesn’t have to be any particular color. The MTFMapper program doesn’t like either vertical or horizontal edges, nor does it like edges at 45 degrees, due to the way the program’s mathematics work. To abide by this rule, all you need to do is slightly rotate your camera or your subject before photographing it. You’ll get different resolution measurements of the same target, depending upon which angle the target edge is at. Almost all lenses resolve differently in the sagittal (spokes away from the lens center) and meridional (perpendicular to sagittal) directions. Rotate the target or camera to enable getting the kind of measurement (sagittal/meridional) you want. To get the best results from this program, you’ll want to shoot your photographs in raw format (definitely NOT in jpeg format). I have some raw-format camera files that MTFMmapper can’t understand, because it uses the library called LibRaw to decode the raw files. My Nikon Z8 and Z9 ‘high efficiency’ compressed raw files can’t be used as-is by MTFMapper, but all I have to do is convert them into the DNG format. The MTFMapper program (using the Libraw library) understands DNG, and you can use the free Adobe DNG Converter program to convert nearly any raw format into DNG. Resolution measurement of a 500mm lens with 1.4X teleconverter As shown above, the MTFMapper program was able to measure the resolution at the edge of a clamp I attached to a fence. It got a resolution measurement of MTF50 50.3 lp/mm, which is the same as 2404  l/ph (lines per picture height). I used my Nikkor 500mm PF with a 1.4X teleconverter on my Nikon Z8 to take this 700mm f/8 shot from 58 feet (17.7m) away. I wasn’t able to set up my resolution test chart this far away, so I improvised with a clamp to get to the desired distance. I rotated the lens/camera combination so that the clamp wasn’t pointing quite vertical. I made sure that the background was much lighter than the dark clamp, and the background is smooth and out of focus. This clamp is large enough to make it easy to place the camera focus point on it, even at long distances. If the camera I’m using has it, I like to use the feature called “Pinpoint focus” to get the most accurate focus. Even the slightest focus error will cause a drastic drop in the resolution measurement. Pinpoint focus also helps ensure that the camera isn’t focusing on the wrong thing when I’m far from the target. The whole field of view for my test setup MTFMapper program option to pick edge(s) As shown above, I used the File | Open with manual edge selection… menu option to open up a suitable raw-format photograph. Select an edge to measure I mouse-clicked two locations on the edge that I wanted to measure. After clicking the first edge location (little orange circle above), I watched the histogram display (lower left of dialog) while I selected the second location (mouse move) to complete the edge selection. The histogram feedback helps you ensure that you get a clean selection that can be properly analyzed. If you decide to change your mind after selecting an edge, then you can click Clear ROIs (Region Of Interest) and select another edge location. It’s also possible to select multiple edges (regions) to analyze. You can fine-tune your edge selection by mouse-dragging the little orange circle to another location after your initial selection. Just watch the histogram while dragging the orange circle to optimize your selection. Slightly different location, different measurement I re-measured the edge, using a different section of a shorter length, and got a different answer. Here, I got an MTF50 resolution measurement of 55.7 lp/mm (2663 l/ph). This probably means that the edge I’m measuring looks more consistent over a short selection length of the target. This is a pretty cheap clamp, and not a super-precision edge. Multiple short regions could have been selected along the edge to compare them, too. After you have selected a suitable edge, then click Accept and allow the program to calculate the resolution at your selected edge(s). Make sure that you set up the correct options for your camera sensor (under Settings) before doing the manual edge selection, including the sensor pixel size. Selecting lots of edges of a printed resolution chart The screen shot above shows how I have selected numerous places in a photo of a test chart to analyze. Some of these selections are poor/illegal, to demonstrate what kind of feedback will result. If you select an unsuitable edge for the program to analyze, you might get an error message when you request that the program begins the analysis. You’ll either need to select another location or another subject to measure. Program feedback Successful measurements (looking at the annotated results) are displayed in cyan. Unreliable answers (45-degree sloped edges) are displayed in yellow, and failed answers (vertical or horizontal edges) are shown in red. I set up my program options to display the answers in MTF50 lp/mm units. Another kind of target I sometimes use a razor blade as a target when I’m shooting at fairly close distances. I use an LED light to back-light the blade, so it shows up as a silhouette. In the shot above, I requested measurements on 3 sides of the blade. If I’m far enough away, it doesn’t matter if I select the sharpened razor edge or another edge. I placed a white background directly behind the blade to get good contrast. Using a precision edge from a caliper (indoors) I have a handy little dual-clamp device with a pair of adjustable alligator clips that I used to hold a precision caliper. The program feedback (under the histogram) indicated that the caliper’s edge selection was 114.5 pixels. The minimum allowed selection length is about 40 pixels, but I’d recommend always using more than this. The annotated resolution result Again, when I select shorter sections of the edge I almost always get a higher resolution reading since the program sees less overall edge variation. The MTF50 result here was 58.2 lp/mm (2782 l/ph), or within about 4 percent of the reading from my Workpro clamp outdoors with the same 700mm lens/teleconverter combination. This shot was done at 40 feet (12.2m). The caliper’s edge is un-coated stainless steel, but I set up a strong backlight to get a good silhouette. Whatever target you try to use for getting resolution measurements, the choice had better be carefully thought out. Rough or crooked edges just won’t cut it.  Let the program’s histogram feedback be your guide for selecting a good edge. As always, this is a ‘garbage in garbage out’ scenario. Using lone edges like this won’t give you the comprehensive results that a proper resolution chart will, but if all you want is a handful of measurements then this should work fine. This is also a good way to compare a printed test chart’s quality against a precision edge. Summary It's hard to beat free. If you can locate a suitable subject with a good edge on it, you should be able to get lens resolution measurements. As I have said many times on my site, thanks again to that very clever Frans van den Bergh!

The Nikon camera “Pinpoint” focus mode is supposed to be the most accurate way to focus their lenses. It’s only available when in “AF-S” mode (not AF-C), so it’s only useful for static targets. On DSLRs (D850 & D780), it’s only available in Live View; I think all of Nikon’s Z cameras support Pinpoint focus. Is this mode really better than other focus modes? That’s what I am going to analyze in this article. My personal favorite focus mode is “3D-tracking”, although I use various other modes if unusual subjects get focused better with the other focus options. In the tests that follow, however, I will compare Pinpoint focus against just the 3D focus using the Nikon Z9 camera. I chose to use the Nikkor 24-120 f/4S lens at 120mm for testing. Nikon cautions that Pinpoint focus might be a little slower than other focus modes, but I didn’t notice any slowdown while shooting with anything except my 700mm f/8 setup (500mm + 1.4X TC). It supposedly only sees a quarter of the area of single-point focus mode. Pinpoint is supposed to use contrast-detect (hence slower), while the other focus modes are strictly phase-detect on their mirrorless cameras. Pinpoint AF-area mode selection Pinpoint mode indicator Note that you have to set the camera to AF-S (single AF focus mode) to have Pinpoint AF as an option. To conduct the tests, I placed the camera onto a sturdy tripod and attached a wired remote release to activate the shutter. I was 17 feet (5.3 meters) from the resolution target. In between each shot, I would alternate de-focusing the lens either too near or too far before pressing the AF-ON button. I waited at least 5 seconds before taking each shot, to allow any vibrations to stop. The whole resolution chart I placed the focus point in the center of the frame, so that’s where I used the resolution measurements for my analysis. I shot 19 photographs with each focus type, in order to get a good feel for the consistency of focus.  In none of the shots that I took was I able to visually tell the difference in sharpness. The only way to note a difference was to use my MTFMapper software to analyze the resolution target photographs. Resolution results for the central portion of the test target As shown above, I had my MTFMapper program analyze each test target raw-format photo and then display each measured target edge. I would pick the best reading inside the red square for my data. The resolution readings shown are in units of MTF50 line pairs per millimeter. Resolution plots showing the entire FX frame The plots shown above provide resolution data about the whole lens field of view, from edge-to-edge. There’s one plot for meridional direction (tangent to a circle) and sagittal direction (like wheel spokes) measurements. I concentrated on just the 32 resolution readings around the center of the lens (both meridional and sagittal), since that’s where I had the camera focus point placed. Test Results The Pinpoint focus data from the 19 test shots had a peak MTF50 reading of 72.7 lp/mm, with an average of 69.2 lp/mm. The standard deviation was 1.93 lp/mm.  Very consistent focus. The 3D-tracking focus data from the 19 test shots had a peak MTF50 reading of 72.7 lp/mm, with an average of 68.5 and a standard deviation of 3.24 lp/mm. Note that both focus modes obtained the same peak resolution of 72.7 lp/mm, but 3D focus was a little sloppier and averaged slightly worse resolution as a result. I have to admit that Pinpoint focus is in fact more consistent, and on average gets marginally sharper shots. The spread of data is pretty small, and you couldn’t notice any sharpness differences by looking at the actual test chart photos for either the Pinpoint or 3D shots. The MTFMapper software is super picky, and it notices subtle differences you can’t perceive yourself. In case you wondered, in the past I compared 3D-tracking against other AF-C focus modes and I didn’t note any particular sharpness differences in the various modes. I just prefer how frequently 3D will hold focus on the desired subject, compared to other modes. The Nikon Z8 and Z9 camera autofocus accuracy is very good and quite fast, no matter which focus mode you choose. Since these cameras focus at the shooting aperture (through f/5.6), it also means that you don’t pay a sharpness penalty using lenses with focus-shift (spherical aberration), either. If you’re after the consistently sharpest shots you can get, then Pinpoint focus is the way to go. If you happen to have the Nikon Z8 camera, then combine Pinpoint focus with pixel-shift shooting for really sharp shots when using a tripod and there’s no subject movement (use either the 16 or 32-shot options).

So what exactly is lens diffraction? Why do photographers hate it so much? How do you get rid of it? That’s the mystery that this article will unravel. That evil Airy disc Camera lenses, even if they’re built to absolute perfection, still make fuzzy images when you stop down their apertures too much. A pinpoint of light, after it travels through your lens aperture on its way to your camera sensor, gets ‘diffracted’ . Instead of hitting the sensor as a pinpoint, that spot of light ends up looking like the picture above. This light-dark-light circular pattern is called an ‘Airy disc’. In three dimensions, the Airy disc would look like ripples after a stone gets dropped into calm water. A guy named George Airy (1801-1892) first developed the mathematics for this diffraction phenomenon, and from then on it’s been known as an ‘Airy disc’. Sir George Airy was a professor of mathematics at Cambridge University. He became an expert in Latin, ancient Greek, architecture, astronomy, and engineering, just to name a few of his skills.  He even supervised the construction of London’s Big Ben chimes. But I digress. If you look at the picture above, the exact size of the Airy disc is ambiguous.  It just gets dimmer and dimmer at the fringes. When a lens aperture is stopped down, the size of this Airy disc starts growing in diameter. The Airy disc diameter is only a function of the aperture f-number and the color (frequency) of light. When apertures are idealized as being a perfect circle, the Airy disc diameter, measured in microns, can be estimated to be 1.34 times the aperture f-number for green light (549nm or 0.549um). For blue light, for instance, the Airy disc diameter is smaller. Green light can be between 500nm and 600nm, but 549 was chosen here. The Airy disc formula is: Airy_disc_dia = 2.44 * frequency_um * F_stop For the above, frequency_um = 0.549 This is why integrated circuits that get made by projecting an image onto silicon use ultraviolet light. This very high frequency light (short wavelength) produces a really small Airy disc diameter. The Airy disc is the culprit in making even ‘perfect’ lenses produce soft images, if they get stopped down far enough. For you to notice the image getting fuzzy, the size of this Airy disc has to grow until it covers more than a single pixel on your camera sensor. A rule of thumb is to start getting concerned about diffraction when the Airy disc grows to be two pixels across or more. For making prints, this rule can be loosened up considerably. For camera sensors that have anti-alias filters (to help rid any Moire effects) the images are even fuzzier. For an example, I’m going to pick on the Nikon Z9 camera, which has pixels that are 4.35 microns and NO anti-alias filter. Two pixels, then, cover 8.7 microns. We don’t care about the overall size of the sensor or how many megapixels it has, either; we only care about the distance between one pixel center and the next pixel center. If that pesky Airy disc covers a pair of pixels, then diffraction can be seen. Diffraction versus F-stop As shown above, when the lens (any focal length) gets stopped down to f/8 or narrower, the Airy disc diameter grows larger than two pixels (8.7 microns for Nikon Z9). As soon as this 2-pixel threshold is reached, some image softening starts. At f/8, diffraction is barely noticeable. Diffraction starts growing in leaps and bounds by f/16, and image quality suffers. Don't even ask about f/32. You have to decide if getting that large depth of focus is worth it. On cameras that support focus-stacking, it’s ideal to stick with f/5.6 or wider and take multiple shots to later combine them to get a large depth of field at optimal resolution. Just pick your lens’s sharpest aperture, and hope there’s no wind. Tripod required. You can manually re-focus between shots, if your camera doesn't have focus stacking. This is a trick to sidestep diffraction effects when there's no subject movement. If you buy a camera with huge pixels, you might get away with one or two extra f-stops before diffraction rears its ugly head, but eventually it will show up. When you hear the phrase “diffraction–limited”, it means that any lens aberrations except for diffraction have been essentially eliminated, so that any remaining aberrations all fit inside that darned Airy disc.  Making the lens optics even more perfect is pointless. Diffraction is always lurking. This lens fuzziness can’t be solved by money. It’s physics. Thanks, George (I guess).

Here’s an idea that probably most photographers have never explored: reflections by themselves. Nearly everybody has shot subjects that include reflections in water to get a nice symmetry. How about skipping the actual subject and just photograph it’s reflection in isolation? The main technique here is to either flip or rotate the reflection to get it upright. You don’t want a ‘perfect’ reflection, either, because then it would just be a repetition of the subject. I like to shoot reflections in infrared as well, to create an even more unique look. With color infrared, I like to switch around the color channels or make hue shifts, so that the sky is blue. I like using the Capture One editor when working on color infrared, and a link to how I use this editor for infrared is here. With water reflections, timing is everything. If the water’s surface is still, the reflection is boring. If it’s windy, the reflection is ruined. If the water has minor ripples, you’ll never get the same shot twice. Contamination floating on the water’s surface can give the illusion of a starry sky. May the wind not be at your back. 590nm infrared reflection, edited in Capture One 590nm infrared reflection, edited in Capture One