I will attempt to contain myself during this lens review, but it won’t be easy. This lens is something special. Sigma had a really, really big challenge to try and beat the legendary Nikkor 14-24mm f/2.8 lens. They won, pure and simple. My praise is primarily centered on the resolution measurements I conducted using the MTFMapper program. Simply amazing results. Sigma 14-24 f/2.8 on Nikon D610 Everybody has come to expect Sigma to be simply first-rate with build quality, and they don’t disappoint. I have read that Sigma made this “Art” lens as weather-resistant as their “Sports” series, although I didn’t personally do any tests to back up that claim. The lens comes with a nice zippered semi-soft case and strap, plus a slip-on lens cap. If you look at some other reviews of this lens, such as Lenstip here and LensRentals here, you will find that they both agree with me about this lens. Except mine generally tested better than their copies did! Astonishing. The Sigma 14-24mm f/2.8 DG HSM lens initials mean that it's full-frame (DG) and it uses Sigma's hypersonic motor (HSM) for auto-focus. It omits the "OS" designation, which means the lens doesn't support image stabillization. Since this lens is a member of the Art, Sports, and Contemporary series, it means that the lens can converted by Sigma between Nikon, Canon, Sigma, Sony, and Pentax mounts. I have to admit that this is a tough lens to test. It has such an extreme wide field of view that you have to be super close to the test chart. My resolution results are at a subject distance of 0.7 meters to 1.2 meters, even using my large A0 (4x5 foot) resolution chart. The chart also had to be aligned parallel to the image sensor with incredible precision, or the else measurements were affected. This means that lens resolution at infinity focus can only be inferred. About the only things missing from this lens are optical stabilization (Nikon doesn't, either) and the ability to use front-mounted filters. The Canon version of the lens can be fitted with rear-mounted gels, if you buy their little add-on filter kit. You can also buy third-party adapters for breathtakingly huge front-mounted filters, if you really want them. Sigma also has this massive advantage over Nikon and Canon: their USB dock to program new firmware and focus calibration for both different distances and multiple focal lengths. Customize the calibration at 14, 18, 20, and 24mm with 4 distances each, or 16 total calibrations. You can also get Sigma to convert the lens to a different camera mount, for a fee. To achieve their optical and mechanical quality, Sigma was forced to make this lens large and fairly heavy. I’m used to big lenses, so it’s a non-issue for me. I always use battery grips; the lens balance is just slightly front-heavy on my D610. Lens Specifications Zoom rotation: 80 degrees through the 1.7X zoom range. Focus rotation: 110 degrees Non-removable petal-shaped lens hood. (Sigma can convert it to a shorter round hood for a fee). Fluorine front lens surface coating to repel dirt and water. Angle of view: 114.2 through 84.1 degrees. Close-focus 0.26 meters (6cm working distance) 9 diaphragm blades 17 elements in 11 groups 3 FLD elements, 3 low-dispersion SLD elements, 3 aspherics. Minimum f-stop: 22. Electromagnetic aperture, like the Nikkor “E” lenses. 1150 grams (different weights for different camera mounts) 96 x 132 mm dimensions. Auto-focus is with Sigma’s hypersonic motor (HSM). Manual focus override by just turning the focus ring. The only lens switch is for auto or manual focus (I just leave it parked at “AF”). There’s a distance scale (meters, feet) but no depth-of-field scale. General Impressions I never noticed the delay while focusing, so I’d have to say it’s “fast”. Focus speed becomes a non-issue in an ultra-wide lens, anyway. It’s also quiet, although I’m not a picky cinematographer. I never had any missed focus shots, either. The focus ring felt silky smooth and perfectly damped; you could easily rotate the focus ring with a single finger. You’ll notice that the image magnifies a little bit as you focus closer, but this “focus-breathing” isn’t objectionable. The zoom ring is quite a bit more damped than the focus ring, and the zoom ring is nearest the camera. It’s still a totally smooth rotation, but is a bit challenging to rotate with one finger if you’re in a hurry. The rubber zoom ring has a wider spacing on its ribs compared to the focus ring, for additional tactile feedback about which ring is which. I think it’s just the right distance from the camera body for zooming with my thumb and middle finger while the camera body/grip rests on my palm. I didn’t notice objectionable vignetting in my photos, although it certainly exists; you’ll only tend to notice it at all with a clear blue sky at wide apertures. As long as it doesn’t draw attention to itself, I tend to ignore vignetting. I also didn’t notice any lateral or longitudinal chromatic aberration, although my editing software would rid it automatically, anyway. The pronounced bulbous front lens element is prone to catching the sun in shots; a lens with this many elements is inevitably going to show multiple reflections, which mostly look green. I try to use my hand to cast a shadow and help out the lens shade when possible. You’re bound to find yourself using the “healing brush” after a day of shooting, however, to clean up lines of green reflections. Bokeh isn’t really a useful discussion with a lens this wide. What there is of it looks decent, but not excellent. Consider it to be a non-issue. Distortion The lens has low barrel distortion at 14mm, and virtually none beyond 15mm. It’s a simple type of distortion that can be removed easily in your photo editor. Worst-case 14mm barrel distortion hardly detectable Distortion 14mm corrected in editor 24mm no distortion seen Resolution Tests Like everybody else, I read a few reviews on this lens before I decided to buy it. Those other reviews agreed that the resolution was a bit better than the Nikkor 14-24 f/2.8 lens. My own tests make me think that I got a better copy of the Sigma than most of the other reviewers did; the resolution was striking for a super-wide lens. I use the MTFMapper program to perform resolution and focus tests, which you can get here. I have an article about the MTFMapper use here. All of my resolution tests are done using unsharpened, raw-format from my Nikon D610 (24 MP). I use live view and contrast-detect focus, to eliminate any concerns about focus calibration. I’m showing the best results from about 10 shots at each focal length and aperture tested. I halted each resolution test after stopping down to f/16, because the diffraction effects ruin the resolution beyond this aperture. The lens stops down to f/22, if you really need it. I haven’t seen resolution characteristics quite like these before. The results at shorter focal lengths show a sort of sine wave pattern of sharpness, versus the expected gradual tapering-off as you move away from the lens center. You might want to avoid using a focus point at 6mm and 12mm from the screen center, unless you use live view or stop down the lens to about f/5.6 or beyond. The resolution numbers in the center of this lens are quite astounding. The edges are better than expected, although the meridional versus sagittal results at a few focal lengths show a fairly large separation (astigmatism). I’m guessing that the use of the 3 aspherical lens elements causes the unusual-looking resolution progression as you move from the lens center toward the edge. Seeing the 14mm f/2.8 resolution results, I can’t wait to travel to the mountains and try out some starscapes away from the city lights that I unfortunately have to contend with. 14mm f/2.8 MTF50 lp/mm resolution These results are just remarkable. I show the results separated out into both sagittal and meridional directions across the whole image sensor (Nikon D610). This is a very unusual pattern that I haven’t seen before. Note the subject distance is only 0.71 meters to cover the test chart dimensions of about 4 by 5 feet. I can’t answer how the resolution numbers might change when focused on infinity. The usual MTF contrast plot, but made from real measurements The contrast plot above (14mm f/2.8) shows how lens resolution is usually depicted, except MTF contrast plots from most manufacturers are “theoretical performance” without considering the camera sensor. This plot is from the actual measurements on the camera sensor. A close-up from the middle of the resolution target The shot above shows a portion of the resolution target photo center, although it is overlaid with the edge resolution measurements in “cycles per pixel”. You have to know the sensor pixel size (5.95 microns here) to convert into other resolution units. As noted in the picture, I saw a peak resolution of 65.3 lp/mm. This is the same as 3133 lines per picture height, in the sagittal direction. The meridional direction peak resolution was 63.6 lp/mm or 0.38 cycles per pixel. Test chart corner, 14mm f/2.8 The extreme corner of the resolution chart is shown above. On many lenses, you only see numbers like these in the chart center. Wow. It’s crisp right out to the corners. . 14mm f/4.0 resolution and MTF contrast plot 14mm f/5.6 14mm f/8.0 14mm f/11.0 14mm f/16.0 16mm f/2.8 16mm f/4.0 16mm f/5.6 16mm f/8.0 16mm f/11.0 16mm f/16.0 20mm f/2.8 20mm f/4.0 20mm f/5.6 20mm f/8.0 20mm f/11.0 20mm f/16.0 24mm f/2.8 24mm f/4.0 24mm f/5.6 24mm f/8.0 24mm f/11.0 24mm f/16.0 Coma Tests I use a little laser behind a tiny hole in aluminum foil to substitute as a star. The lens is focused on infinity, and the target is about 15 feet away. The images shown are at the pixel level (100% magnification). All shots are in the extreme corners of the sensor. I included some comparison shots using my Tokina 11-16 f/2.8 lens. It’s considered very good, but you’ll see that the Sigma clearly beats it, even though the Tokina results are on a DX sensor and the Sigma is on an FX sensor. I also included a shot at f/4.0 to compare to f/2.8 results. There’s almost no difference when stopping down, because the Sigma is so good even wide open. The size of the coma looks the same in all corners of the sensor. Only the orientation of the coma changes. Tokina 11-16 coma at 11mm and 16mm reference images Sigma 14mm wide open versus f/4.0 coma Sigma 14mm coma top left and right corners Sigma bottom right corner Summary This lens is strongest at the short focal lengths, which is how I would prefer it to be. I wouldn’t consider it to be “weak” at any focal length, however. The Sigma is a bit of a specialty lens, given its extreme field of view. I’ll bet that architectural photographers make this a favorite for interior shots. Landscapes, to me, are all about emphasizing the foreground; this lens delivers that in spades. As I had already mentioned, I can’t wait to try this lens out for starscapes. You don’t want to have to stop down a lens for star shots, and it doesn’t look like you need to stop down with this lens. The Sigma 14-24mm f/2.8 DG HSM lens is another major statement by Sigma that they're now in the top tier for producing professional-grade lenses. Sample Pictures 14mm 1/60 f/7.1 ISO 125 14mm 1/60 f/9.0 ISO 160 14mm 1/125 f/16 ISO 100 14mm 1/1000 f/5.0 ISO 100 14mm 1/160 f/10.0 ISO 100 24mm 1/800 f/4.0 ISO 100 22mm 1/800 f/4.0 ISO 100 #review

Sigma TC-1401 Teleconverter on their 70-200 f/2.8 Sport lens You can see how tiny the Sigma TC-1401 teleconverter is. It’s only compatible with a few Sigma lenses, so be careful to do some research first to see if it will work for you. It won’t work on Nikkor lenses. Similarly, I don’t think the Nikon teleconverters will work on Sigmas; I haven’t tried it, but they warn against it. I didn't check to see the compatibility combinations with other companies such as Sony or Canon. Being a 1.4X teleconverter, you’ll lose one stop of light; my Sigma 70-200 f/2.8 Sport becomes a 98-280 f/4 lens. Most of my teleconverter tests, by the way, were done using the Sigma 70-200 f/2.8 Sport. This teleconverter is dust and splash-proof, so it has about the same specifications as their “sport” series of lenses. It has 7 elements in 5 groups, so there’s more complexity here than you’d think. It weighs 6.7 ounces, or 190 grams. Sigma claims that you can autofocus at up to f/8, but it autofocused fine on my Sigma 150-600 C at 600mm and f/6.3, which would actually make the final f-stop go to about f/9. I tested this on a Nikon D850; many cameras with less sensitive autofocus will struggle or fail with this combination. At any rate, stick with the “f/8 focus sensors” on your camera. Also, stick with decent light levels if you expect any performance using autofocus on this lens. Some of the lenses compatible with this teleconverter include their 120-300mm f/2.8, 500mm f/4.0, and the 70-200 f/2.8 Sport, 100-400 f/5-6.3, 60-600 Sport, in addition to their 150-600 lenses. Pretty slim pickins. Sigma has many busy bees designing for them, though, so I’d expect a larger selection of compatible lenses in the future. I almost exclusively use this teleconverter on my 70-200mm. There’s not enough of a resolution drop or speed penalty to bother me. I don’t think I’d have the same opinion with a 2X teleconverter, but that’s just me. Lens padded case It comes with a little zippered case and lens front/rear caps. No belt loop or clip on it, unfortunately. Focus Speed I measured the impact on focus speed by setting my 70-200mm lens at 200mm, f/2.8 (which then becomes 280mm f/4.0 with the teleconverter). I set the minimum focus distance (about 4 feet). I then timed how long it took to focus on infinity (using phase-detect of course) under sunny conditions. I measured 0.45 seconds, compared to 0.36 seconds on the same lens without the teleconverter. I used the “High Speed AF” algorithm for this test (programmed via their Sigma USB dock). I used “slow-mo” video at 240 fps to review the focusing action (looking at the focus scale). The TC-1401 teleconverter only slowed the lens focus speed down by about 25%. It was hard to even notice a focus slowdown when using the teleconverter. I had braced for something much worse than this. Caution: I wanted to mention that you have to put the teleconverter onto the lens before you mount it onto the camera, or else autofocus won’t work. You have been notified. Sigma USB Dock Sigma USB dock calibration settings: TC-1401 + 70-200 Use Sigma's Optimization Pro along with their USB Dock to calibrate your lenses in combination with the teleconverter. The calibration settings for the teleconverter shown above are saved separately from the (70-200mm lens) calibration settings. Those clever Sigma engineers know that the lens focus calibration won’t be the same with and without a teleconverter. Your own settings would, of course, be different from these. Bravo, Sigma engineers. Vignetting and Chromatic Aberration The teleconverter reduces the level of vignetting, since you’re using the center of the lens field of view. I didn’t notice enough chromatic aberration to mention with this combination; my editing software would remove any if there was some. Bokeh I don’t think that bokeh was altered enough to notice. It’s quite good on my 70-200, and the teleconverter didn’t mess it up. Distortion I couldn’t see any changes to lens distortion when using the teleconverter, either. Lens Resolution I use the MTFMapper program to perform resolution and focus tests, which you can get here: I have an article about the MTFMapper use here: My resolution chart size is 40” X 56”. Testing with big charts provides a more realistic working distance; the actual resolution target distance is included in each plot below, via the exif data. All of my resolution tests were done using unsharpened, raw-format from my Nikon D850 (45.7 MP) with the Sigma 70-200 f/2.8 Sport. I use live view and contrast-detect focus, to eliminate any concerns about focus calibration. I’m showing the best results from about 10 shots at each focal length and aperture tested. I halted each resolution test after stopping down to f/16, because the diffraction effects ruin the resolution beyond this aperture. Even f/16 starts the resolution plunge, but sometimes you need the depth of field. The f/16.0 setting would be the physical f/11.0 of the lens itself, coupled with the one-stop light loss from the teleconverter. 98mm f/4.0 MTF50 lp/mm resolution The 70mm f/2.8 setting had a center resolution of about 62 lp/mm, or about a 10% resolution loss by adding the teleconverter. The focal length gain is 40%, so this is a win. 98mm f/4.0 MTF contrast plot The sagittal and meridional plots track each other amazingly well here. 98mm f/5.6 MTF50 lp/mm 98mm f/8.0 MTF50 lp/mm 98mm f/11.0 MTF50 lp/mm 98mm f/16.0 MTF50 lp/mm 145mm f/4.0 MTF50 lp/mm 145mm f/5.6 MTF50 lp/mm 145mm f/8.0 MTF50 lp/mm 145mm f/11.0 MTF50 lp/mm 145mm f/16.0 MTF50 lp/mm 195mm f/4.0 MTF50 lp/mm 195mm f/5.6 MTF50 lp/mm 195mm f/8.0 MTF50 lp/mm 195mm f/11.0 MTF50 lp/mm 195mm f/16.0 MTF50 lp/mm 280mm f/4.0 MTF50 lp/mm Without the teleconverter, the lens at 200 mm f/2.8 had an MTF50 lp/mm of about 58 in the center, or about a 22% resolution loss for the 40% focal length gain. 45 lp/mm is still very, very good. This is probably the measurement that people will be most interested in: Wide open at maximum focal length. 280mm f/4.0 MTF Contrast Plot 280mm f/5.6 MTF50 lp/mm 280mm f/8.0 MTF50 lp/mm 280mm f/11.0 MTF50 lp/mm 280mm f/16.0 MTF50 lp/mm Summary You get a 40% focal length increase at the cost of a stop of light and between about a 10% to 20% resolution loss, using Sigma’s TC-1401 teleconverter. You also lose about 25% in focus speed. Again, these numbers were all measured using Sigma’s 70-200mm f/2.8, but you get the idea. I think these modest losses are far outweighed by the gain in focal length. I doubt you’ll even notice the added weight or physical length increase, either. Don't be afraid to shoot with a combination like this wide open. I wouldn’t bother putting this teleconverter on Sigma’s 150-600 lenses, except in special cases. Maybe for 840mm moon shots. Every once in a while, you just can't have too much focal length. I’m very happy with this teleconverter, and it’s always with me when I take the 70-200 anywhere. Sample Shots You won’t notice any sharpness loss. 98mm f/4.0 Closest focus, 280mm f/4.0 It’s the bee’s knees 280mm f/4.0 It doesn’t mess up those out-of-focus backgrounds. . #review

70-200 and Nikon D850, mounted on Arca-Swiss foot The 70-200mm f/2.8 is one of the primary lenses that most professionals and serious amateurs have in their lens arsenals. The Sigma 70-200mm f/2.8 DG OS HSM Sport lens is Sigma's second major version of this lens, and the first of its kind in their "Sports" line. The nomenclature for Sigma initials is as follows: DG means it's full-frame coverage. The OS means it supports optical stabilization. The HSM means that is has Sigma's "hypersonic motor" for autofocus. As is typical for modern Sigma lenses (Contemporary, Art, Sports), they offer a conversion service to change its mount between Nikon, Canon, Sony, Pentax, and Sigma. You can see the switches for focus options, focus-limit, optical stabilization, and custom settings from the top to the bottom in the image above. The round button in front of the switches is one of three programmable auto-focus buttons; the others are on top of and underneath the lens. The focus ring is nearer to the camera body than the zoom ring. The knurled knob near the top-rear of the lens is for locking the tripod collar. Lens padded case General Impressions Sigma revamped an already-good lens and made it better. Or maybe I got an especially good copy. I’m mainly interested in resolution and focus speed for this focal length range, and it delivers both. It also has the legendary weather sealing of the “sports” series of lenses and every characteristic of a fully professional lens, including very good optical stabilization. The exterior lens optical surface has a fluorine-style coating to resist oil, dirt, and water. Sigma’s lens kit also includes a super nice padded case for the lens, a bayonet lens hood with a lock button, and it also comes with a rotate-able tripod collar that has a combination Arca-Swiss (yes!) and conventional ¼-20 tripod thread on the foot. The tripod collar is rock solid. They include hex keys if you want to remove the foot (the collar stays put). I’d recommend you leave the foot on, since it’s at the proper balance point for the lens. The edges are rounded, so it’s comfortable if you use it as a carrying handle with the camera upside-down. The collar has nice click stops at every 90 degrees, after you loosen the knurled knob. As a signature of a pro lens, it includes three programmable AF function buttons (you press whichever one is nearest your finger while zooming). You can use these to initiate focus or lock focus; program them using the Sigma USB dock. There’s also the “Lens focus function buttons” assignment in the camera custom controls. There’s even a programmable focus-limiter switch. Again, use the Sigma USB dock to change its distance behavior. The lens doesn't change its length as you zoom. It's not even remotely close to being parfocal, in case you wondered. This is a big, heavy, tough lens. Sigma’s philosophy is that “it weighs what it weighs”. Their prime motivation is optical results and survivability. It weighs almost exactly 4 pounds and is 8 inches long, sans lens hood. I totally agree with Sigma’s philosophy; don’t sacrifice features or quality just for the sake of weight. I know backpackers will wholeheartedly disagree with this philosophy (I used to be a backpacker myself). I think that the correct mantra is “Resolution, quality, light weight; pick any two”. The barrel is magnesium alloy, and it sports the “E” style aperture which supposedly works better at stopping down while shooting high frame rates. Speaking of the aperture, it has eleven blades, which are rounded (to optimize the bokeh). It uses 82mm diameter front-mounted filters. I’d skip using any UV “protective” filter on this lens; use its deep lens hood for protection instead. You should always be using the lens hood for better quality photos with all telephotos anyway; there's a lot of glass in this lens. It’s already weather-sealed, so filters aren’t needed for that purpose, either. You’ll probably need to lose the lens hood if you try a polarizer, however; it’s too hard to gain access to rotate it. I did all of my testing using the Nikon D850. Lesser cameras may show worse resolution and focus speed measurements. Ironically, this lens didn’t impress me much with the first few test photos I took. Here’s why: the lens needed auto-focus calibration in the worst way. Fortunately, this lens supports the Sigma USB calibration dock. Focus is now perfect at every focal length and at every distance (the D850 AF fine-tune value remains at zero). You can focus calibrate at 4 focal lengths and 4 distances per focal length. Nikon still hasn’t caught on with this feature; they only let you calibrate at a single distance and a single focal length. Blech. In the resolution charts below, the "exif" data shows the AF tune value of "0". That just means the focus tuning is kept inside the lens, so that the camera body can be left at zero. My Sigma USB dock calibration settings I’ll never understand photographers that will pay big bucks for camera gear and never even think about calibrating it. What a shame. While I had the lens on the USB dock, I went ahead and programmed its “custom” switch settings (C1 and C2). I program the C1 switch to use the “Moderate View” optical stabilization algorithm and the “High Speed AF” algorithm. I program the C2 switch to use “Standard AF” algorithm and “Moderate View” stabilization. When the custom switches are both off, then the lens uses “Standard AF” and “Standard View” stabilization. By the way, the stabilization “view” you program has no effect on the actual lens stabilization anti-shake capabilities for the photograph. It’s only a viewfinder preference. At least I couldn’t tell any difference with vibration reduction performance (which seemed excellent to me). It sounds really petty, but my biggest complaint with this lens is the lens cap. It’s very fussy to attach it, particularly if you leave the lens hood on. I’m tempted to get a Nikon cap for it (they fit nicely on it). Focus Speed I measured the focus speed by setting the lens at 200mm, f/2.8 and minimum focus distance (about 4 feet). I then timed how long it took to focus on infinity (using phase-detect of course) under sunny conditions. I measured 0.36 seconds. I used the “High Speed AF” algorithm for this test. I used “slow-mo” video at 240 fps to review the focusing action (looking at the focus scale). I found the focus accuracy and repeatability to be excellent. I see no reason yet to switch to a slower autofocus algorithm. Sigma put their “hypersonic focus motor”, which they call HSM, into this lens. If you’re interested in how fast it focuses, then you’d be foolish not to use their USB dock and program it for the “high speed” focus algorithm. They also have a special “smooth” focus algorithm that’s designed for video use, but it’s the opposite of fast. I found that on another lens (the Sigma 150-600 C) that the "High Speed AF" algorithm is about 20% faster than the "Standard AF" focus algorithm. Teleconverter I also tried using Sigma’s TC-1401 1.4X teleconverter (280mm and f/4.0). The same focus test took 0.45 seconds. The teleconverter only slowed the lens down by 25%. I’ll work on a review of their teleconverter later, but (spoiler alert) I found it to be very good with this lens. I wanted to mention that you have to put the teleconverter onto the lens before you mount it on the camera, or else autofocus won’t work. You have been warned. Also, Nikon teleconverters won’t work on the Sigma. Likewise, you shouldn’t put a Sigma teleconverter onto a Nikkor lens. You have been warned. Twice. Sigma also makes a compatible 2X teleconverter (TC-2001) for this lens; I haven’t tried it. I can go for f/4 but I’d rather not go for f/5.6. Sigma USB dock calibration settings: TC-1401 + 70-200 The calibration settings for the teleconverter shown above are ALSO saved, separately from the 70-200 calibration settings. The Sigma engineers are clever enough to know the lens focus calibration won’t be the same with and without a teleconverter. Your own settings would, of course, be different from these. I’m constantly impressed with those Sigma engineers; it’s almost as if they photograph stuff themselves, as opposed to my impression of Nikon and Canon engineers. Lens Stabilization I don’t have a very scientific method for testing this. I just zoom out to 200mm and try my best to hold the lens steady on a high-contrast target. I got sharp images with 200mm and 1/15 second more than half of the time. This equates to about 4 stops of anti-shake; your own mileage will vary. Their “Mode 1” is for general hand-held stabilization; “Mode 2” is for panning operations. In both modes, be aware that it takes about 1 second to be in full stabilization mode after you begin focus or half-press the shutter. Sigma claims 4 stops of stabilization, so I think they’re honest about what their lens delivers. Everybody is different in how they hold their camera, so I don’t think there will ever be a good measure of this specification. Infrared For those who are interested, this lens doesn’t work well for infrared. It has the dreaded hotspot in the middle of the frame. Vignetting and Chromatic Aberration The following shots are some details from one of my resolution targets. They give you an idea of the worst case (f/2.8) on full frame. Chart center with pure white background, 70mm f/2.8 Chart corner. Background definitely not white. 70mm f/2.8 Chart center, 200mm f/2.8 Chart corner, 200mm f/2.8 There is only the barest hint of chromatic aberration; it’s down in the ignorable region. I couldn’t detect any longitudinal chromatic aberration. Vignetting is what I’d call “medium”. The shots above give you an idea of worst-case corner vignetting (f/2.8). Decide for yourself if this bothers you. You can of course correct for vignetting in your favorite editor. Bokeh I quite like the bokeh, but this is something you can’t really put a number on. They’ve done what they can with the rounded 11-blade aperture. Distortion There’s a small barrel distortion at short focal lengths and really tiny pincushion at the long focal lengths. There’s not enough to bother with, in my opinion. Lens Resolution I found the resolution-versus-focal-length trend to be the same as I have read on other web sites. It’s weakest at 135mm, but that’s not to say it’s “weak”. You’ll see below that the results are generally in the category of very, very good. The meridional (tangent) direction resolution is generally worse across the board compared to the sagittal direction. This is consistent with probably 95% of all lenses. I’m not aware of any other websites that give you resolution separated into meridional and sagittal directions; they just give you “the number”. The two-dimensional plots below demonstrate how to really understand a lens’ resolution characteristics; a single resolution number is basically nonsense. There’s really no such thing as “the edge” or “the corner” resolution; it’s typically changing all along each edge. To me, resolution above about 30 or 35 lp/mm looks good, so this lens looks really, really good. The extra resolution just means that you can crop to your heart’s content. As always, I am only reviewing a single lens copy. I use the MTFMapper program to perform resolution and focus tests, which you can get here. I have an article about the MTFMapper use here. My resolution chart size is 40” X 56”. Big charts provide a more realistic working distance; the actual target distance is included in each plot below. All of my resolution tests are done using un-sharpened, raw-format from my Nikon D850 (45.7 MP). I use live view and contrast-detect focus, to eliminate any concerns about focus calibration. I’m showing the best results from about 10 shots at each focal length and aperture tested. I halted each resolution test after stopping down to f/16, because the diffraction effects ruin the resolution beyond this aperture. Even f/16 starts the resolution plunge, but sometimes you need the depth of field. The lens stops down to f/22, if you really need it. 70mm f/2.8 MTF50 lp/mm resolution These resolution results are first rate. I show the results separated out into both sagittal and meridional directions across the whole FX image sensor (Nikon D850). The center peaks at about an MTF50 of 62 lp/mm or 2962 l/ph. Let me repeat: that’s at f/2.8. The usual 70mm MTF contrast plot, but actual measurements The contrast plot above (70mm f/2.8) shows how lens resolution is usually depicted, except MTF contrast plots from most manufacturers are “theoretical performance” without considering the camera sensor. This plot is from the actual measurements on the camera sensor. You can tell that astigmatism is fairly minimal, since the meridional and sagittal plots track each other pretty well. 70mm f/4.0 MTF50 lp/mm resolution The center peaks at about MTF50 70 lp/mm or 3346 l/ph. 70mm f/5.6 MTF50 lp/mm resolution 70mm f/8.0 MTF50 lp/mm resolution 70mm f/11.0 MTF50 lp/mm resolution 70mm f/16.0 MTF50 lp/mm resolution 102mm f/2.8 MTF50 lp/mm resolution (close enough to 100mm) 102mm f/2.8 MTF contrast 102mm f/4.0 MTF50 lp/mm resolution 102mm f/5.6 MTF50 lp/mm resolution 102mm f/8.0 MTF50 lp/mm resolution 102mm f/11.0 MTF50 lp/mm resolution 102mm f/16.0 MTF50 lp/mm resolution 135mm f/2.8 MTF50 lp/mm resolution 135mm f/2.8 MTF contrast 135mm f/4.0 MTF50 lp/mm resolution 135mm f/5.6 MTF50 lp/mm resolution 135mm f/8.0 MTF50 lp/mm resolution 135mm f/11.0 MTF50 lp/mm resolution 135mm f/16.0 MTF50 lp/mm resolution 200mm f/2.8 MTF50 lp/mm resolution 200mm f/2.8 MTF contrast 200mm f/4.0 MTF50 lp/mm resolution 200mm f/5.6 MTF50 lp/mm resolution 200mm f/8.0 MTF50 lp/mm resolution 200mm f/11.0 MTF50 lp/mm resolution 200mm f/16.0 MTF50 lp/mm resolution Summary This lens is strongest at the short focal lengths, which is typical of just about all zooms. It isn’t, however, “weak” at any focal length. The Sigma 70-200mm f/2.8 DG OS HSM Sport lens is a total winner in my book. The 70-200 acts and feels very professional in all regards. This lens will not disappoint you, provided that you take the time to calibrate its focus. I mean calibrate it by using the Sigma USB dock, where you calibrate multiple focal lengths and distances. While you're at it, program its "High Speed AF" focus algorithm, too. I really love the bokeh that this Sigma provides. I'll bet wedding photographers will snap this lens up. Sample Pictures Bokeh sample. Very smooth and creamy. Distance shot, which needs some cropping Detail from shot above The lens is so good that you can do pretty extreme crops and still get good detail. A good camera sensor doesn't hurt, either. Those eleven rounded aperture blades really help here Details come through edge to edge #review

This document was created to explain in simpler terms how the mtf_mapper_gui.exe program works. The program has two main purposes, (1) to aid camera focus calibration (2) lens resolution measurement. This program and other programs offered at the link below actually do a lot more, but this is what most photographers are interested in. The MTF Mapper program author is Frans van den Bergh. His software and printable test charts are available here: Frans comes across as a scientist-type guy, and his documents can sort of take your breath away. They’re worth a read, though, even if you can’t grok 100% of their contents. More of his writings about image analysis topics can be found here If you like his stuff as much as I do, please let him know! MTF Mapper uses a program called “dcraw” (included in download) that knows most “raw” formats, and is regularly updated for new cameras. The "MTF" refers to Modulation Transfer Function, which refers to how light/dark transitions happen. "MTF50" refers to the highest line frequency (line pairs per millimeter) you can have before 50% of the contrast is lost. Values above about 30 lp/mm are considered pretty good, and anything above 50 lp/mm is outstanding. Resolution Measurement To start out, here’s some typical “Profile” output from his program: Resolution profile plot. Lens MTF50 is about 50 lp/mm To make a profile plot, there are a couple of things that need to be done first: Print out a test chart; print it big, mount it flat, use good heavyweight glossy paper. A0 (about 33” X 47”) is great. "Satin" finish papers work well, too. You may need to change the MTF site test chart file formats from ".svg" (scalable vector graphics) into something your program likes better, such as ".pdf". There is freeware that can do this. Make sure you stick with “raw” mode with your camera, and don’t sharpen the pictures. Photograph the chart (‘contrast detect’, live view mode is recommended) in diffused light. I find that a "+1.0" exposure compensation works best to keep the white background light. Run mtf_mapper_gui.exe File | Open… then pick the picture(s) to analyze Click on “profile” on the right-hand side after the picture analysis finishes. You don’t have to wait for the other pictures to get analyzed. Resolution chart with ‘slanted squares’ provided by Frans The resolution chart has little slanted squares that mostly look like spokes branching out from the chart center. The measurement algorithms work best with edges that have a slant around 5 degrees. The “spoke” structure is ideal to get measurements that can be separated into the sagittal and meridional directions, like most MTF plots are. Unfortunately, the spokes nearest a 45-degree “X” pattern get slightly higher measurements than they should (a few percent higher). For most people, this is a “don’t care”. See below for more information on this, if you’re the “care” type. “MTF50” is a pretty stringent measurement. Most manufacturers give you MTF10 (contrast measure) and MTF30 (sharpness measure). Annotated picture up close The ‘annotated’ picture above shows a zoomed-in view of the measurements for each whole square the program could locate. Good measurements are in green. Marginal measurements are in blue (typically within a degree of 0, 26.565, or 90 degrees). Bad measurements are in yellow. If squares are too small (less than 25 pixels per edge) you get a bad measurement. You don’t have to photograph the whole chart; it finds and measures only whole squares. The chart doesn’t have to fill the viewfinder, but don’t let the chart squares get too small (less than 25 pixels). You’ll probably want to add more exposure than your camera meter indicates; you want a light background with the black squares. If the meridional measurement on a square is different from the sagittal measurement, you have astigmatism. You’ll probably notice that the sides of the squares parallel to each other have measurements that nearly match each other. Don’t get too sloppy here. Bad chart rotation can spoil readings. Diffuse light works better than ‘hard’ light. Use a tripod, remote shutter release or self-timer, and mirror-lockup to avoid vibrations. Bump up ISO if you need to for higher shutter speeds, since higher ISO speeds doesn’t mess up the results nearly as much as blur does. I equate the direction “sagittal” to “spoke”, like spokes on a wheel. The term “meridional” is sometimes called “tangent”, and it’s perpendicular to the “sagittal” direction. Note that different resolution camera sensors will give different MTF50 results; this is normal. Remember to set the "pixel size" in the program 'Preferences' to the correct pixel size! How to convert “cycles per pixel” into other measurements Assume the camera sensor is 3264 X 4928 pixels, or about 15.7mm X 23.6mm. Assume an edge measures 0.27 cycles per pixel. MTF50 lp/mm = cycles_per_pixel * height_pixels / height_mm MTF50 lp/mm = 0.27 * 3264 / 15.7 = 56 lp/mm Line pairs per picture height = Lp/ph = lp/mm * height_mm Lp/ph = 56 * 15.7 = 879 Customize the way mtf_mapper_gui works In Settings | Preferences check the “Line pairs/mm units” if you want these units in the “profile” plot. Verify your camera’s pixel size (microns) in the same Preferences dialog. The Nikon D7000, for instance, has a pixel size of 4.78 microns. A D7100 camera is 3.92 micron pixel size. 2-D Grid Plot of Entire Resolution Chart (D7000) Select the “grid2d” to see the resolution measurements throughout the sensor. The pair of plots separate out Meridional and Sagittal readings. This shows that meridional results are better than sagittal results at this f-stop. I like this chart the best of all the available outputs, since it gives a complete picture of the sensor performance, and it separates the readings to get the best understanding of astigmatism (when sagittal/meridional values are different). There’s a “grid3d” plot if you want it, which is basically taking a 2D plot and viewing it at an angle to get the third dimension. Weird “X” Pattern If you ever notice a sort of “X” pattern that fills most of the 2D plot, but only has a difference range of a few percent, it’s an artifact of the square shape of the camera sensor photo sites (its pixels). Frans has an article about this at the download website. Don’t freak out; your lens doesn’t have some kind of cloverleaf inside it. The “green” sagittal cloverleaf readings above are reading slightly better than they really are; the ’52’ scores are probably nearer to ‘50’. If the chart squares were all locked at a 5-degree tilt, the effect would go away, but then you don’t get to see the sagittal/meridional separation. This is the tradeoff being made. The “Imatest” guys opted for the “only 5-degree squares” and sacrificed providing sagittal/meridional data. Frans says he might someday provide both kinds of charts, so you get to choose which you like better. Focus Calibration Focus Chart provided by Frans showing where to focus For focus tests, print out the focus chart and mount it flat. Photograph it while it’s slanted 45 degrees from your camera, with the left-edge (above) of the chart farthest away from you. There are a few charts to choose from; choose the chart that best matches your lens focal length so that the picture looks most like a rectangle instead of a trapezoid. Only use your “phase detect” autofocus setting (not contrast detect live view) to focus the chart, since the point of this test is to test the phase detect system. Use fairly bright light (typically EV10 or better) to make sure your camera doesn’t have to hunt for focus. Use your center focus sensor, and aim it as shown above in red. Plot of focus chart photo The above results show a slight focus error. The camera focus fine-tune (or the lens fine-tune if it’s a new Sigma lens) will need a (-) adjustment to pull the focus nearer to the camera. You might find it easier to determine the focus error by looking at the "annotated" picture values instead of relying upon the "profile" image. Take several shots before you decide how much to change the focus calibration. Each test will probably be a little different. Photo of Chart. Notice the annotated squares added by mtf_mapper_gui.exe The focus sensor was trained on the center of the big rectangle (trapezoid, actually) vertical right edge. Chart was mounted at 45 degrees, with the left side of the chart farther from the camera. #howto

How it gets information in and out of the lens Sigma sells a USB dock (it looks like a hockey puck) tailored to your lens mount type. It’s cheap enough that you have no excuse not to buy it. The software is free from Sigma. It retrieves the connected lens model, mount type, serial number, firmware version, and customization settings using the Optimization Pro program. It sends firmware updates and any customization settings into non-volatile memory inside the lens. One dock will work with all of your Sigma lenses that support the USB dock (unless you have a mix of Nikon/Canon/Sigma/Pentax/Sony bodies). Older Sigma lenses don’t support this. Optimization Pro Features Firmware updates Update the algorithms for anti-vibration, focus speed, manual focus ‘throw’, and even future added features that haven’t been invented yet (such as focus fine-tune for different apertures on fast lenses? Are you listening, Sigma?) It lets you get any firmware bug fixes without having to send your lens to the factory, and it enables Sigma to alter any communications interface changes, in case Nikon or Canon get cute and try to make a compatibility-breaking change in the future. Tammy (sorry, I mean Tamron) and Tokina users might be out of luck if the lens communications requirements get changed in the future. The lens firmware version is checked when the program gets executed while the lens/dock is connected, so you don’t have to remember to request update checks. Focus Fine Tune For zoom lenses, it can calibrate focus at 4 distances for each of 4 focal lengths (16 total settings). The distances are (1) closest focus (2) near range (3) far range (4) infinity. For prime lenses, you can calibrate focus at 4 distances only. Now, even multiple copies of a lens can be custom-calibrated. Nikon, for instance, can’t tell the difference between two copies of the same lens model, and only knows a single fine tune number to apply. It’s very annoying when you have two camera bodies and you have to mark which lens to assign to which body (I paste the fine-tune value inside each lens cap, along with the lens serial number). Sigma can read its lens serial number electronically, so every lens is unique. Nikon and Canon et al. need to pay attention to details like this. Also note that lower-end cameras with no focus fine-tune can still get tuned lenses if they’re Sigma and use the dock. I think all AF lenses could benefit from this kind of focus fine-tuning intelligence. Real-world zoom optics need different fine-tuning at different focal lengths and different distances, but so far only Sigma seems to acknowledge this problem even exists. The 16 fine-tune settings for my 150-600mm Contemporary zoom Notice the different characteristics of each focal length shown in the “Focus Setting” fine-tune screen. The pathetic single AF shift value that my Nikon D7000 offers would leave the lens functioning very poorly indeed. The available shift range is plus/minus 20. Now I can finally leave my camera AF tune setting on “0”. I suppose a second camera body using this same lens would need a non-zero AF fine-tune value, but at least that would shift all 16 in-lens settings. Note the “Rewriting” button in the dialog box above that should say “Save” instead. Don’t be one of those people that get caught staring at this screen waiting for “Rewriting” to finish. I personally use MTF Mapper software and special focus test charts to evaluate critical focus. MTF Mapper is free; the author is Frans van den Bergh (this guy is absolutely brilliant). His program is available here: . This software lets me get really accurate information to enable me to enter good offset data into the Optimization Pro Focus Setting screen. MTF Mapper can also be used to evaluate lens sharpness, but that’s a topic for another day. It’s an iterative process to estimate the focus offset values to use, reprogram the lens with Optimization Pro, re-photograph the focus test charts, and then re-analyze the photos to see how you did. MTF Mapper uses “dcraw.exe” to decode RAW files, which is frequently updated for new cameras from most vendors. Focus chart analyzed and annotated by MTF Mapper program The above (unsharpened, RAW) photo shows one of the iterations to evaluate focus accuracy. This particular focal length and distance shows a focus error which will require the fine tune value to be decreased to pull the focus more toward the camera. The MTF Mapper web site also provides graphic files that have the test chart images for printing (both focus charts and resolution charts). I mostly use A0 size prints (about 33” X 47”) mounted onto a board; the bigger the chart, the better the results. I also print onto heavy glossy paper. Regular uncoated, lightweight paper sucks for trying to mount it and keep it totally flat. The more diffuse illumination you use when photographing the chart, the better. Also, you want bright light to give your camera focus system the most help (EV 10 or better for most cameras). Charts are of course useless for the “infinity” test shots. With long focal lengths, heat shimmer is a real problem. Maybe something like craters on the moon in cool weather would work best; I have used really distant tree branches or pine needles (600 – 900 feet) with the long focal lengths. Detail from the annotated focus chart created by MTF_Mapper_Gui program Profile view of the focus chart from MTF Mapper program The focus chart large vertical edge is depicted as the vertical blue line above. The smoothed plot of each measured square is depicted in green. Each individual square edge reading is plotted in red (units of MTF50 line pairs/mm). Focus is properly calibrated when the blue line aligns with the green peak. The above plot is from a test of the Sigma 150-600mm Contemporary lens at 600mm at f/6.3 using a Nikon D7000 camera. Note that a few edges actually measure over 40 line pairs per millimeter (and this is considered worst-case sharpness for this lens)! Focus testing was done using AF-C mode (with ‘focus’ button), and it is actually pretty repeatable. This is how this lens is mostly going to be used, so I tested it using the same focus mode. Test-to-test variation was pretty small. I shoot 10 shots at each focal length and distance, and then choose the average focus distance to decide how it is calibrated. By the way, the tested lens (150-600 Contemporary) had zero focus chatter in AF-C. The focus locked and stayed there on the target. This is very un-like my 70-300 Nikkor that chatters constantly, even in good light on high-contrast targets. It’s extremely annoying, and a deal-breaker for me. I read that the new Nikkor 80-400 AF-S VR has the same annoying focus chatter (see the review at photographylife.com). I used to think the chatter was a camera body problem, but now I realize it’s a lens problem. Chatter equals missed focus about half of the time, and focus fine-tune is an exercise in futility. But I digress. Full view of focus chart at 600mm at 19 meters (with annotation text). Note that the focus chart large ‘rectangle’ shown above is actually a trapezoid, to help counteract perspective. The large black ‘rectangle’ edge nearest the photo edge is actually much taller than the large edge in the center of the photo. The little squares are also farther apart vertically at the left edge than the right edge. Use high shutter speeds to eliminate any motion blur side effects; high ISO values have minimal effect on MTF measurements compared to motion blur, so don’t be afraid to push it to get blur-free pictures. I also use my infrared remote unit with mirror lock-up to rid vibrations, in addition to a big-honking tripod. Just remember: “garbage in, garbage out”. It’s worth your while to do careful focus calibration. If you read reviews of a Sigma lens that supports the USB dock but the calibration wasn’t done, then don’t put too much stock in the review in regards to focus accuracy. In this case, the saying goes “nothing in, garbage out”. I don’t see any fundamental reason why Sigma can’t do all of this focus calibration at their factory, but talk is cheap here. Hey, at least they’re giving us the tools to help ourselves. No other manufacturer is even close to this level of sophistication (yet). There a bunch of videos here from a Canadian company that go into detail about using the Sigma software and Sigma topics in general. #howto

The exiftool program lets you extract all of the data out of your photographs into a text file by a simple drag-and-drop operation. This is a really easy way to get at exposure, lens, and camera data, plus much more. You can find out how many total shutter-actuations your camera has done, the “Light Value” (or EV) of the scene, the depth of field, whether you used phase-detect or contrast-detect, etc. What you can’t get is the Nikon lens serial number, although you do get the camera serial number. It’ kind of cool that my Sigma 150-600 Contemporary lens data even gets correctly decoded while on my Nikon. I can give it my RAW files directly, plus a bunch of other formats. You can get this free program here: The author is Phil Harvey. Please thank him! Thank you, Phil. Phil’s software can do many things beyond what I mention here, but here’s how I use it in Windows (Mac OS-X is supported). Select the exiftool.exe file in Windows Explorer Right-mouse click and select Copy and paste into the same directory. Right-mouse click exiftool –Copy.exe and rename it: exiftool(-a -u -g1 -w txt).exe Now, all you have to do is go to a directory with photos and drag/drop a file onto the exiftool(-a -u -g1 -w txt).exe program. You will get a text file (same name as the dropped file, but with a .txt extension) placed right next to the original photograph file. Simple and elegant. Sample Data From Typical Output Text File This program is really, really useful. It's also a real eye opener to know just how extensive the amount of data kept in every photograph really is. Thank you Phil Harvey! #howto

What can you expect from a lens when you change to a higher resolution camera? For crummy lenses, don’t expect improvement. Good lenses, though, are another story. Let’s compare the Nikon D7000 (16 megapixel) against the D7100 (24 megapixel) cameras. The D7000 sensor is 3264 X 4928 pixels, while the D7100 is 4000 X 6000 pixels. Both sensors are the same size, at 15.6 mm X 23.6 mm. Resolution change is evaluated in a linear fashion, so it’s the change in the ratio of either the short or long edge measurement of the sensor, such as 6000/4928 = 1.22, or 22 percent more with the D7100. Doesn’t sound nearly as sexy as 24MP/16MP = 1.5 or 50% bump, does it? If a lens has good enough optics, then you would expect your MTF50 measurements would therefore increase by about 22% by upgrading from the D7000 to the D7100. But wait, there’s more! What about that removal of the OLPF (optical low-pass filter) on the D7100? At the risk of moiré in some pictures (never actually observed by me in any of my pictures yet except for shooting a “Siemen’s star” target) you can squeeze a bit more resolution out of a sensor when you stop fuzzing-out the image by getting rid of that low-pass filter. Low-pass (e.g. don’t pass high-frequency light/dark transitions) filters stop those nasty color patterns you used to see watching TV when some guy would wear a pin-stripe suit. If the pinstripes were spaced at the same interval as the camera sensor elements, it really messes up the image. The OLPF filters work by de-focusing the image a little bit, and therefore ruins those fine details in your carefully-focused picture you paid big bucks to get. You get the lost resolution mostly recovered by using the “un-sharp mask” in your favorite image-processing program. It always seemed a real hoot that “un-sharp” was used to get “sharp”. Another way to get rid of moiré is to use the "moire removal" feature in many modern image-processing programs designed specifically for that task. In any event, moiré is a “don’t care” for most people and most photographs. After that major digression, let’s get back to lens resolution and camera sensors. We’re expecting about 22% improvement in MTF50 measurements, not counting the OLPF filter removal. This assumes the lens resolution isn’t already maxed-out on the D7000. MTF50 results for Sigma 150-600mm lens on D7000. MTF50 results for Sigma 150-600mm lens on D7100. Using the above Sigma lens results, we get a MTF50 high-reading change from 40 to 48, or about 48/40= 1.2 = 20%. On the low end, the change is from 26 to 30, or 30/26=1.15 = 15%. Next, let’s check out my best-resolving lens: MTF50 results for Nikkor 85mm lens on D7000. MTF50 results for Nikkor 85mm lens on D7100. Using the above Nikkor 85mm f/1.4 AF-S lens results at f/4.0, we get an MTF50 high-reading change from 54 to 68, or 68/54 = 1.26 or 26%. On the low end, the change is from 46 to 52, or 52/46 = 1.13 or 13%. Conclusion If you have a pretty good lens, you can expect to get nearly the theoretical maximum resolution change. It’s unclear (no pun intended) the contribution of the OLPF filter removal to overall resolution, but I’m getting around 26% overall (camera sensor plus OLPF removal). The OLPF removal must be at least 4% improvement. Corners aren’t quite as rosy of a scenario, but still a substantial improvement. BTW, don’t abandon the un-sharp mask when post-processing just because you don’t have the OLPF filter. You’ll still see a huge bump in sharpness. #howto

I want to present details on the lens MTF50 resolution performance and how well the lens autofocuses. I won’t rehash the Nikon specifications of the lens, since that data is readily available in any number of other places. My usual disclaimer: this is looking at a single copy of the lens. Yours will be different, but hopefully ‘similar’. The only place I know of that tests lots of copies of lenses is here. I’d also like to mention some comparisons to the 60mm f/2.8 Micro Nikkor AF-D. There is a lot of talk on the internet about how totally inferior the 60mm is to the 105mm. I personally think that the 60mm is more competitive than people think it is, even with its lack of VR compared to the 105. It’s true that you have more working distance between the lens and subject (6 inches versus 3 inches at 1:1) using the 105mm, but often that extra distance isn’t really needed. The working distance goes down to 2.75 inches at 1:1 magnification if you use the 105 lens hood. These tests were done using a Nikon D7100 (24 MP) with unsharpened 14-bit compressed RAW format. Here is a link to get pretty good information on this lens. They reduce resolution measurement down to a single number for an f/stop setting. It’s not that simple; resolution is a 2-dimensional thing. The focus ring on this lens is nice and wide; nobody can complain about that. You can use it anytime you want to override autofocus. Many people use this lens in manual focus mode only, and only use the focus ring to set the magnification before moving the camera/lens back and forth to focus on the subject. You get a rear rubber dust gasket, but that’s it for moisture/weather sealing. Nikkor AF-S Micro 105 mm f/2.8G IF-ED VR with Nano-Coating Autofocus Phase-detect focus was very fast on my D7100 in dim light, and very repeatable. I also noticed that Live-view shot-to-shot resolution measurements had almost zero variation; the lens focus motor is really first-rate. There was absolutely no focus chatter, and that’s crucial (lenses that have focus chatter are useless, in my opinion). I noticed no focus calibration shift at different f/stops. Focus was basically silent (unlike my micro Nikkor 60mm f/2.8). I don’t have a single lens that doesn’t need some focus fine-tune calibration. This lens is no different. If your camera doesn’t have fine-tune, you need to save up and buy one; refurbished cameras are pretty reasonable these days. Your lenses won’t be giving you what you paid for without fine-tune, unless you put up with Live View autofocus. I guess you can manually focus, too (I personally gave up on that the day I got an autofocus lens). Vibration Reduction (VR) This has first-rate VR, which is one of the biggest upgrades over my 60mm f/2.8 AF micro Nikkor. Resolution Testing Now for the real meat of this article. You will get to see the full 2-dimensional resolution of this lens, separated into both sagittal and meridional values. Here’s my customary rant about those lens reviewers that grade lens resolution with adjectives like “good”, “fair”, “excellent”, or “1.5 blur units”. Huh? I want real numbers and I want to see real pictures of things I’d actually bother to photograph. I use a (free!) program called MTF Mapper from here to measure lens resolution. The download site also has files for printing out the resolution targets (mine are A0 size on heavy glossy paper (‘satin’ finish seems to work just as well), dry-mounted onto a board). This program is covered in more detail in another article, but suffice it to say that this is really great stuff; it’s comparable to ‘Imatest’ in the quality of the MTF measurements, and it uses the “slanted edge” technology similar to ‘Imatest’, also. The author of MTF Mapper, Frans van den Bergh, really knows his stuff. Visit his site and give him the praise he deserves. The chart design used for resolution tests orients all of the little black squares to be ‘slanted’ but they’re generally aligned in meridional and sagittal (think spokes on a wheel) directions to correlate better with the usual MTF plots you’re familiar with. There’s often a dramatic difference in sharpness between these two directions, and the chart photographs show it clearly, when it exists. The meridional/sagittal differences are what “astigmatism” is all about. This lens isn’t perfect in that regard, but it’s better than most. What the resolution target looks like. Mine is mounted ‘upside down’. At long last, I’m getting around to some actual resolution results. Tests were done with “Live View” AF-S autofocus, contrast detect, IR remote, VR OFF, really big tripod. That’s how I get around any phase-detect problems with focus calibration. The results don’t seem to improve using manual focus and 100% magnification in Live View, so I don’t bother. I use the “best of 10 shots”; not every shot gets the same resolution results. All cameras operate on the “close enough” principle for focus, so many tests are needed to determine the best resolution that the lens can produce. That said, this lens was so repeatable that they were all just about the same sharpness. Wide open. Already impressive resolution, all the way to the edges. Peak sharpness at f/5.6 These numbers bring tears to my eyes. Diffraction setting in at f/8, but still excellent. Resolution Summary Pick an f/stop according to desired depth of field. You needn’t bother about trading off sharpness with f/stop. Diffraction starts at f/8, but there isn’t that much of a resolution penalty until about f/16. Some people refer to a lens with good resolution and contrast as having 'bite'. This lens has big-dog bite. If you can afford it, get it. Sample Pictures Humming bird warning me I’m too close. 105mm Micro Nikkor, 1/60, f/8.0, flash. I combined sharp flash with ambient light at a slow shutter speed to make it a bit more interesting. Detail from above. This is one sharp lens. Hummer posing. I normally don't display blah images like this, but note how SHARP it is. Feather details. #review

This is the Tokina version that uses the screw-drive for auto-focus. It has the same optics as the newer internal-focus motor “Pro II” version. The newer version also claims to have improved anti-reflection coatings. I have read that some users find the newer “Pro II” to be less sharp than this original version, but I suspect it’s just lens sample variation they’re seeing. I’ll concentrate on the lens resolution performance in this article, in addition to my observations on any unusual behavior I have noted in using it. Some people are averse to lenses that use the “screw drive” focus, but for me it’s basically a “don’t care” when the focal length is small (e.g. non-telephoto). Focus is still plenty fast (camera model dependent) and actually one of my more repeatable lenses for phase-detect focus. An interesting thing I noted on focus is that the “live view” autofocus wasn’t consistent. This is the exact opposite of what typically happens with other lenses, where the “phase detect” is less consistent. I got such consistent results with phase detect that I used it for the resolution tests and got absolutely repeatable results. Since I only have one copy of this lens, I can’t say if you will see this effect or not. Although it’s a “DX” lens, it has full frame coverage on FX at the 15mm-16mm lengths. I’ve read that corners are fairly soft on FX, but I haven’t tested it. Update 6-10-2016: I have tested it on a Nikon D610. It's very good at 16mm, but I don't like the level of vignetting at 15mm. See the my review here. Tokina built this lens for professionals, so it’s a metal and glass hulk. It’s actually quite beastly in size and weight. It uses 77mm filters; I keep a UV filter on it, mainly because the front element is challenging to clean due to its substantial curvature. What you get for that big diameter: f/2.8 and constant-aperture while zooming! What you don’t get: vibration reduction. Not such a big deal on short focal lengths, however. These tests were done using a Nikon D7100 (24 MP) with unsharpened 14-bit compressed RAW format. I actually left the UV filter ON for the tests; the filter doesn’t have any measureable effect on resolution results. I’ll let the pictures at the end of this article speak for themselves in regards to the anti-reflection coating and contrast. Yes, you’ll get internal reflections to show up when you point it at the sun; you will get flare when you “provoke it”, so don’t provoke it! The lens also has a proper metal lens mount and gasket (rubber seal). That’s it as far as dust/weather resistance is concerned. I read plenty of complaints about the focal length range only going from 11 to 16. I bought this lens for 11mm, so I really don’t care about how ‘long’ it can get; you’ll have to decide if this is important to you or not. You can bet that a longer focal length range would result in more optical problems. I am very pleased with the optical quality of this lens. It would be nice if the corners were a bit sharper, of course. But when you compare it to the competition, you’ll see that the corner performance is actually first-rate. Note that in the resolution plots below you can get really good corner performance when you stop down. Although this is a rectilinear lens, you’ll notice barrel distortion, particularly at 11mm. Since you can correct it using your favorite image editing software, it’s not a big deal. For landscapes, it is a total non-issue about 99% of the time. I bet you won’t even notice distortion when you get to 16mm. What I didn’t notice was vignetting, which surprised me. Take a look at the sample photos at the bottom. Make it disappear with your image editor if it bugs you; same goes for any lateral chromatic aberrations. This is a really great video lens. If you mess with focus while shooting video, you’ll want manual focus; it works by pulling the focus ring toward you to engage a clutch. I didn’t notice any focus breathing (grow/shrink image size with focus change), either. It also appears to be “parfocal”, so you don’t need to refocus after zooming. Tokina 11-16mm f/2.8 with removable lens hood (plus 77mm UV filter). Resolution Testing This is why you should read this article. My goal is to enable you to evaluate resolution between lenses in a standard, scientific way. I also give you the information (see my MTF Cliff’s Notes article) to be able to repeat these tests for yourself. Resolution measurements are in MTF50 lp/mm. This measurement represents how many image line pairs can fit inside a millimeter before the white-to-black chart transitions degrade to 50%; e.g. “turn to mush”. For me, anything beyond about 30 lp/mm is fine, and beyond 50 is outstanding. Higher-resolution sensors yield higher measurements, much like you’d expect. Before I forget, you will notice a couple of tiny weird blobs in some of the resolution plots that follow. Please ignore these, since they are definitely not a lens imperfection. The measurement software is extremely sensitive, and an imperceptible chart surface indentation shows up very clearly in the measurements. I use a (free!) program called MTF Mapper from here to measure lens resolution. The download site also has files for printing out the resolution targets (mine are A0 size on heavy glossy paper (‘satin’ finish seems to work just as well), dry-mounted onto a board). This program is covered in more detail in another article, but suffice it to say that this is really great stuff; it’s comparable to ‘Imatest’ in the quality of the MTF measurements, and it uses the “slanted edge” technology similar to ‘Imatest’, also. The author of MTF Mapper, Frans van den Bergh, really knows his stuff. Visit his site and give him the praise he deserves. The chart design used for resolution tests orients all of the little black squares to be ‘slanted’ but they’re generally aligned in meridional and sagittal (think spokes on a wheel) directions to correlate better with the usual MTF plots you’re familiar with. There’s often a dramatic difference in sharpness between these two directions, and the chart photographs show it clearly. The meridional/sagittal differences are what “astigmatism” is all about. This lens is decent in the sagittal direction when you get away from the lens optical center. Meridional direction isn’t nearly as good; this is the “norm” in most lenses. The middle of the lens is beyond impressive, as you’ll see. What the resolution target looks like. Mine is mounted ‘upside down’. Finally, I’m getting around to some actual resolution results. Tests were done with phase-detect back-button autofocus, IR remote, and a really big tripod. As I mentioned before, this lens likes phase-detect better than contrast-detect focus. I use the “best of 10 shots”; not every shot gets the identical resolution results. All cameras operate on the “close enough” principle for focus, so many tests are needed to determine the best resolution that the lens can produce. MTF Mapper “focus target” plot. Note the “+15” fine-tune for phase detect. Focus fine-tune was set to +15 to calibrate this lens to my D7100. Take a look at my MTF Mapper Cliff’s Notes article if you’re curious about the details. The lens is so wide that I had to have my A0 target at only 1 meter away. Distortion Analysis Worst-case distortion at 11mm showing the resolution target Same 11mm photo after software distortion correction 16mm uncorrected distortion. I don’t see any distortion. Resolution Results The following measurements were done at the extreme focal lengths of the lens. 11mm wide open. Great center, corners not very good. f/5.6 has outstanding center, and now corners are quite good. Diffraction is killing resolution at f/16 16mm wide open. Again, corners aren’t that good yet. f/4.0 has exceptional center, and corners are now fine f/16 and diffraction is again killing resolution f/22: Don’t go there. Sample Pictures Great for emphasizing the foreground. 11mm Drinking Dragon (Los Arcos). 16mm. #review

One of the more obscure features offered by the Nikon D850 is the ability to directly convert your color or black and white film negatives into digital positives. There are of course companies that still offer to convert your film to digital, but many people want to do this activity themselves. The file output format created by the D850 when using the “negative digitizer” is strictly jpeg, even if your camera is set to record as NEF. A word of caution: this feature is unavailable if your camera settings are configured to use live view “silent photography”. The “Negative digitizer” option will be greyed-out if this mode is active. D850 with Negative Digitizer active You don’t have much control over the photograph in-camera; you can’t even control the colors. You’ll need to provide good lighting, such as normal daylight, for the conversion to be successful for color negatives. You can adjust the brightness, if needed. Please, please dust off your negatives first; the healing brush in your editor gets really tiresome. Gear Selection Nikon PB-4 Bellows and PS-4 slide copy adapter I have the Nikon PB-4 bellows and the Nikon slide copy adapter PS-4 that fits onto it; this is still the Cadillac system for copying filmstrip negatives and mounted slides, in my estimation. I also use my old Micro-Nikkor 55mm f/3.5 pre-AI lens, which is absolute perfection for life-size copying of film with this bellows and slide copy attachment. I had to remove my vertical battery grip from the camera to mount it onto the PB-4. I also had to place the PB-4 camera mount into vertical orientation to attach/detach the camera; once attached, I could rotate the camera into the horizontal (landscape) orientation. Additionally, I had to move the rear bellows back to its end of travel on the rack to attach or detach the camera. You need diffuse, even lighting to illuminate your film; the slide copy adapter provides exactly that with milky white glass behind the negative, which also keeps the film flat. I use a wired remote release, to eliminate any vibration concerns. Copying Procedure Once your have your negative mounted in front of your camera, you’ll first need to switch into Live View. Make sure you’re using a good full-spectrum, “daylight-balanced” light source. Zoom in (the “+” button) to make sure that your negative is properly focused (with a wide-open aperture). I like to use the Live View “focus peaking” feature to make manual focus much simpler. Step down the aperture to the sharpest setting (e.g. f/8.0) after focus is confirmed. Next, press the “i” button and choose the “Negative digitizer” option, which will either have a “CL” or “MC” icon displayed to indicate this option. Press the “up/down” multi-selector to get to the icon. The camera remembers the last digitizer mode you had selected. The two options for using this feature are “CL” for “color negative” mode or “MC” for “monochrome”. Press the “right arrow” to select the color/monochrome screen, and then press the “up/down” arrows to select which CL or MC option you want. Press “Ok” after the color/monochrome is selected. Your exposure mode will be automatically set to “A”, and you cannot change it. Press the “Ok” button, when prompted, to adjust the brightness, and then press “Ok” after finishing your brightness adjustment. Take the shot. Live View with an old “orange film” color negative I always thought that the old orange color negative film looked particularly terrible. I never fully understood the necessity to add the awful orange cast to everything, including the film edges. Negative Digitizer “CL” mode When you enter the CL mode, the view you get is worlds better than the orange and purple “negative” view. Live View with a black-and-white negative Notice the little red “focus peak” marks on the LCD; this makes critical manual focus much simpler. Negative Digitizer “MC” mode The “positive” view of your negative in MC mode is slightly different than the recorded image; the recorded image is definitely better. Finished photo from color negative conversion Color negative film doesn’t age nearly as well as black and white film. The shot above is from 1993. There’s not a lot that can be done to fix fading, but at least the digital version will stop any more fading. Maynard Ferguson, 1976. Converted from film negative. I’m impressed by how faithfully the black and white negatives get converted into positives. The tonal range seems excellent to me. That being said, working with these film negatives reminds me how modern digital sensors totally smoke film. More tonal range, more sensitivity, and more resolution. I made the shot above with a Nikon F2 and Nikkor 300mm f/4.5 lens (and these still perform as well today as the day I bought them). If black and white film is properly developed and stored, it can last multiple lifetimes. There doesn’t appear to be any change to this negative over the 44 years of its existence. I remember that I used Tri-X pushed to ASA 1600 for this concert (ISO used to be called ASA). Conclusion The Nikon D850 provides a simple way to see and photograph your negatives as positive images. Since it only provides jpeg output, you don’t have as many knobs to adjust the output as you may be accustomed to having available when shooting Raw. Most of my old color film work was done with slides; I always disliked color negatives. If all you have is color negatives, here’s your chance to convert them to digital before they fade away. Go ahead and convert those slides while you’re at it, even if you don’t need the “Negative Digitizer” feature to do it. I have always had an affinity for black and white, and I have a huge body of work done with film. I think that this D850 feature works really well for converting those negatives into digital positives, without much loss of sharpness or tonal range. I’m really glad that Nikon added this little-advertised feature to the D850. We need to praise and encourage the Nikon engineers for thinking up new ways to expand the power and usefulness of their cameras. It’s a comfort to finally have some backups for my film negatives. I admit that I’m way past due in getting this done; my video tapes got digitized years ago, but I neglected my stills. And rest in peace, Maynard.

Short answer: heck yes. But it depends. This is one of the internet topics that go round and round with lots of hand waving, but not much to back up opinions. I decided to test it for myself. Turns out that it's a bad idea if you don't turn off VR with high shutter speeds. You’ll lose about 9% of resolution with your shutter at 1/1000 if you leave vibration reduction (VR) ON. Turn it off if you go above 1/1000! It's lens-dependent in the range between 1/500 and 1/1000. My Sigma 150-600 generally works best with vibration reduction ON between 1/500 and 1/1000. BUT not all lens VR is created the same. The Sigma 150-600 firmware update 1.01, for instance, seems to have changed this story. VR works with higher shutter speeds in this case. Same goes for the Nikkor 24-70 f/2.8 VR; you can use higher shutter speeds at least with these lenses. Check out the link here for more. Present technology in vibration reduction can only run up to so high of a frequency, and that limit corresponds to about 1/500 second. Beyond that shutter speed, it actually hurts more than it helps. Below that speed, it can be an amazing aid to keep pictures sharp. I tried some tests using the Sigma 150-600 Contemporary at 600mm, 1/1000, f/6.3, ISO 2000, using the factory image stabilization (OS) algorithm. I used the 'overall' image stabilization, versus the 'panning' stabilization algorithm, since the viewfinder image showed the subject moving as much vertically as horizontally. The basic idea is the same for Nikkor lenses with "VR", although you don't get as many options for VR algorithms as Sigma provides. I set the lens onto a tripod with a gimbal mount, but I left the gimbal adjustments loose and held onto the Nikon D7100 and used AF-C while I tried to train the focus sensor on the middle of my resolution target at about 55 feet. These are typical shooting conditions, where the subject is jumping around in the frame and you'd swear that VR would be a good idea. Here's the first set of test results: VR (OS) ON while shooting the target with AF-C (using back-button focus). MTF50 Max. MTF50 Min. (corners) 46 28 46 30 46 28 44 30 46 30 44 30 38 30 44 30 42 30 42 28 44 28 34 22 Average maximum resolution = 43 lp/mm Average minimum resolution = 28.67 lp/mm (corners) Here's the second set of test results: VR (OS) OFF while shooting the target with AF-C (using back-button focus). 44 30 48 30 48 30 48 30 46 32 48 30 46 30 46 30 45 30 48 30 Average maximum resolution = 46.7 lp/mm Average minimum resolution = 30.2 lp/mm (corners) Comparing the two tests: 46.7 / 43 = 1.09 = 9% sharper with VR OFF while using 1/1000 shutter. 30.2 / 28.67 = 1.05 = 5% sharper with VR OFF (corners) using 1/1000 shutter. Also, notice that the results vary more when using vibration reduction at high shutter speeds. Therefore, don’t use VR going beyond 1/500 shutter! Unless your own tests of a specific lens indicate otherwise, that is. Life is so complicated. #howto

This review is primarily concerned with resolution. The Nikkor 60mm f/2.8 AF-D seems to have a mixed quality reputation among users. My copy of this lens is really, really good in the center. Corners aren’t so hot until f/5.6. This is an older lens (1993-2008), but it’s built to very good mechanical standards. Note that you will need an upper-end camera body that has a built-in focus motor to use this lens. It’s an “FX” lens, so it will work on full-frame models. I have read lots of reviews where they complained about its short focal length, but on a DX camera I have rarely had any issues with a too-short lens-to-subject distance. This includes many butterfly shots; lighting isn’t a problem, nor do I have much of an issue with scaring bugs away. I generally use an SB-600 flash and “FP” mode outdoors for close-ups with high shutter speeds. I have a separate article on “FP” mode if you’re interested. Please, please don’t use the camera built-in flash. If not for you, do it for sake of art. I have always liked this lens for portraits, too. On DX, the focal length is quite nice. The 2.8 aperture might be considered a limitation for portraits; it’s a matter of your own taste. I’m not saying it’s going to replace my 85mm, but before I got my 85, the 60 was the go-to lens for portraits. Autofocus isn’t perhaps blazingly fast, but it’s not a problem. Maybe it’s just me, but I still like having autofocus available when I’m shooting close-up and hand-holding the camera. Judging sharpness with manual focus just isn’t for me. There’s a “focus limit” switch for quicker focusing at non-macro distances. If you’d rather do manual focus, then press the little chrome "unlock" button on the lens barrel and then rotate the "M - A" ring to “M”. Most people obviously use macro lenses for close-up photography, and I’m no different. I almost always use a flash, and I stop the lens down for depth of field. A bonus with stopping the lens down is resolution; you’ll see below how dramatically the resolution across the frame improves at smaller apertures. Resolution peaks at f/8.0, and then diffraction rears its ugly head after that. The lens focuses down to 1:1 magnification. If you like to standardize on this level of magnification, you may want to consider other lens options that aren’t going to be as challenging for lighting and lens-to-subject distance. It’s only about a 3-inch gap from the front of the lens to your subject at 1:1 magnification! If you want to go through the pain of evaluating your own stuff, then you need to get the MTF Mapper program and print out the resolution target files at that site. The software (as of this writing) is free, and the author Frans van den Bergh is to be commended. The download site is here http://sourceforge.net/projects/mtfmapper/ I discuss using his program in another article. The article is a ‘Cliffs Notes’ version with enough detail to get you started, but without the finer points being included. You really should give Frans’ stuff a read, however, if you want to understand the technology it contains. MTF50 Measurements I measure lens resolution at MTF50. Most published manufacturer MTF charts are at MTF10 (contrast) and MTF30 (resolution). Except for maybe Zeiss and Leica, those MTF charts are “theoretical”, meaning they don’t have much basis in reality. And they don’t ever show the whole frame, which is the only decent way to evaluate resolution. The "MTF" refers to Modulation Transfer Function, which refers to how light/dark transitions happen. "MTF50" refers to the highest line frequency (line pairs per millimeter) you can have before 50% of the contrast is lost. Values above about 30 lp/mm are considered pretty good, and anything above 50 lp/mm is outstanding. I made the tests with a Nikon D7100 (APS-C sensor, 24MP). Bear two things in mind; corners for FX will be worse and other camera resolutions will get different MTF50 values. For instance, the D7000 gets up to 24% less resolution (I tested it). Lesser lenses will show a smaller improvement with higher-resolution sensors, because the lenses aren’t as capable. What the resolution chart looks like The picture above shows what gets photographed (unsharpened, RAW) and evaluated. The program author, Frans, has a couple of chart designs, but the main idea is to align the little squares to get their edges in sagittal (spoke) or meridional (tangent) directions. The squares need a little ‘slant’ to them (5 degrees is optimal) to get measured optimally, similar to what Imatest does. Measurement algorithm problems arise if the little square orientations approach vertical or 26.565 degrees. If you try testing yourself, don’t get too sloppy about orienting the chart, and bear in mind that the squares must always be bigger than 25 pixels on an edge. The chart squares emanating from the center along 45 degrees (“X”) have MTF readings that can be 2 or 3 percent higher than they deserve. This is the tradeoff between the desire to get sagittal/meridional measurements and approaching the critical ‘bad’ slant angles. The Imatest guys have punted on this and don’t align their target squares in sagittal/meridional directions; they have 5-degree slants on all of the squares. You’ll see an “X” pattern on some of the 2D resolution plots below, due to this effect. Resolution Tests MTF50 60mm f/2.8 wide open This is really good performance for being wide open, in my opinion, but NOT in the corners or edges. Note that the EXIF data got messed up for “focus distance”. The tests were done with an “A0” chart size. I don’t have a really good small-sized resolution chart, so tests were done at more conventional distances. Limited testing I tried at closer distances didn’t show resolution improvement, although urban legend says macro lenses improve resolution as you get closer. 60mm f/4.0 MTF50 Notice you get an immediate 40% jump in resolution going from f/2.8 to f/4.0 (just a one-stop difference) in the corners. Again, this is only one copy of the lens being tested; no guarantees on how yours might perform. Only a 9% resolution increase in the center, but resolution was already stellar at f/2.8. 60mm f/5.6 MTF50 I’m getting another 29% resolution jump going from f/4.0 to f/5.6 in the corners, but I didn’t see center improvement; it’s already so good that I can’t complain. 60mm f/8.0 MTF50 This brings tears to my eyes. I’m so proud of this lens! Peak performance everywhere in the frame. This is the aperture to even start to have sufficient depth of field for most close-ups. 60mm f/11.0 MTF50 Diffraction starts at f/11. Still great resolution, so don’t feel you need to avoid this aperture. Beyond f/11, resolution suffers quite a bit. The lens goes to f/32 (f/57 at 1:1 magnification!) for those subjects where depth of field needs to trump resolution. Conclusion I have compared this lens to the 105mm f/2.8 AF-S VR Micro Nikkor, and it is actually sharper in the center than the 105 (by 13%). The 105 smokes it in the corners until f/5.6, though. Again, this is only looking at a single copy of each lens. Both are fine lenses, but the 105mm costs way more. I love my 60mm; it’s a true classic and I have no intentions of giving it up. Now let’s talk about un-sharp corners at f/2.8. Depth of field approaches zero at that aperture when doing actual macro photography. I would virtually never use the lens that way, so corner performance at f/2.8 is a “don’t care” for me. It is only useful for seeing a bright image through the viewfinder and enabling the camera to focus faster. It should be one of the last considerations for buy/no buy decisions unless you’re into astrophotography. Samples Butterfly 60mm f/10, 1/320, ISO 100, SB600 Flash Butterfly 60mm f/7.1, 1/500, ISO 200, SB600 Flash FP mode Lizard Fight 60mm f/18 1/60 ISO 200 Flash Don’t fear stopping down! Sufficient depth of field far outweighs resolution to capture important subject matter. #review