This article will concentrate on the Nikkor 50mm f/1.8 AF-D MTF50 resolution performance and discuss how well the lens autofocuses. Repetition of the published Nikon specifications of the lens will be mostly avoided. This is one of the most popular Nikkor FX “prime” lenses ever produced, known as the “nifty fifty” (the 50mm f/1.4 shares this title, but the price of the 1.8 makes it much niftier). It’s also one of the most inexpensive Nikkor lenses. I’ve paid more for filters than I did for this lens. This is another of the Nikkor lenses that falls into the category of “just get one”. It’s reasonably fast, focuses well, and is one of the tiniest lenses Nikon has made. It has been superseded by the “G” version, which loses the aperture ring. When used on DX cameras, this is a particularly good focal length for portraits (75mm equivalent). What you don’t get: vibration reduction and great corner resolution when the aperture is wide open. 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 was lent another copy of this lens (not being reviewed here) and it was NOT good. You need to verify your own copy; I don’t believe that Nikon tests each lens, or else the other copy I was lent wouldn’t ever have made it out of the factory. These tests were done using a Nikon D7100 (24 MP) with unsharpened 14-bit compressed RAW format. Given this fact, I’m not reporting on the edge performance of an FX sensor. Here is a link to get pretty good information on this lens. My main complaint with them (and most of the other web sites) is that they simplify resolution measurement down to a single number for an f/stop. It’s not that simple; resolution is a 2-dimensional thing (not to mention sagittal/meridional directions within those 2 dimensions). The focus ring on this lens is a wide-enough one, nearest the filter. Being a “D” lens, you can’t just use it anytime you want to override autofocus; you need to set your camera into manual focus mode first. Note: keep your hands off the lens during auto-focus; the focus ring will spin around! I’m guilty of virtually never overriding auto-focus on a short lens like this, so manual focus considerations are a “don’t care” for me on this lens unless I’m shooting infrared. The lens also has a proper metal lens mount, but no gasket (rubber seal). There’s no dust/weather resistance. There is a distance scale. Comes in very handy for infrared when I can’t see the subject through the viewfinder. Also note: DO use this lens for infrared! I use it with the Hoya R72 52mm IR filter. There is no “hot spot” in infrared that often happens with lenses, so it works fine for that purpose (in manual focus mode, of course). Nikkor 50mm f/1.8 AF-D FX with 52mm filter. Tiny lens! Autofocus Only works on cameras with the built-in “screw drive” focus motor. If your camera doesn’t have the screw drive, then you will need the more expensive “G” version of the 50mm. All of my lenses need some focus fine-tune calibration; so does this lens. The focus speed is largely controlled by which camera is attached. I haven’t seen repeatability issues on either my D7000 or D7100, and the focus speed has been more than enough. Vibration Reduction (VR) Nope. Helps keep this lens inexpensive. Even Nikon’s 85mm f/1.4 AF-S doesn’t have VR. Just saying. I wish all my lenses had VR, but such is life. MTF50 Resolution Testing This is why you should read this article. I will provide the information to enable you to evaluate resolution between lenses in a standard, scientific way yourself, if you wish to double-check me. Also, since your lens results will be different than mine, the following results are just a guideline. 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 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. The real resolution reference is the annotated photograph of the resolution chart, which shows each little square’s edge in “cycles per pixel” units. 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, and corners are “okay”. Meridional direction isn’t as good, but judge for yourself in the ensuing resolution plots. The middle of the lens is impressive, as you’ll see. What the resolution target looks like. My target 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 (cell phone, actually), and a 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. Frans van den Bergh has an article on how he tested the Nikon D7000 phase-detect focus accuracy by doing a series of tests starting at minimum focus and then a series of tests starting with the lens focused at infinity. He found a definite correlation showing how the camera stopped focusing once it decided that focus was “good enough”, so the infinity-focus-start series would focus a little behind the target, and the start-at-minimum-focus-distance series would end up with focus a little in front of the target. Acceptable center wide open, but corners are a bit off (f/2.0 is similar). Already good edge-to-edge at f/2.8 Stellar center performance by f/4 Peak performance at f/8 Diffraction is exacting its toll at f/16, but still quite good Sample Pictures Fairy Duster 1/80, f/16 50mm up close. 50mm 1/640, f/8 No color fringing, sharp everywhere #review

Most consumer cameras don’t offer focus calibration (auto-focus fine-tune). Many users of enthusiast/professional cameras ignore focus calibration as “a waste of time”. After all, the factory makes nearly every lens and camera fully calibrated, right? Fully not. Top ten things that can use tuning: Cars Musical instruments Husbands/boyfriends Skis Lasers Voices Radio stations Software algorithms Computers Cameras/Lenses Notice that cameras and lenses just made the list. I have never shot with a camera/lens combination that needed a focus calibration of “zero”. Maybe they exist somewhere. Even the 85mm f/1.4 AF-S Nikkors (I’ve tested two of them) need focus calibration at some of their wider f-stops. What kind of price do you pay by not calibrating? Can you even tell the difference? This article shows you what kind of price you pay. My lenses use focus calibration values that range from as little as “+1” to as much as “-20”. The full range of calibration values among all of my lenses varies from “-20” to “+15”. Since the Nikon range is +/- 20, I’m right on the hairy edge. So what happens if you don’t bother to calibrate? You pay a big price in resolution, that’s what. If you only own really slow lenses or only shoot with the lens stopped down quite a bit, then it might be a truly “don’t care” situation. The higher-resolution camera sensors are even more picky about focus calibration. I did a set of tests with my Nikkor 35mm f/1.8 AF-S (DX) on a D7100. It falls into the category of “average” focus calibration, needing a value of “+7”. Not too much fine-tuning compared to my 60mm Micro-Nikkor that needs “-20”, but still nothing to sneeze at. My D7000 needs a fine-tune adjustment of “-5” with the same 35mm lens on it. The following are my test results, conducted with the MTF Mapper program and using an A0 size resolution chart. I turned on phase-detect auto-focus and then switched auto-focus fine-tuning OFF for half of the tests. I tested shooting wide-open, and then I tried stopping the lens down a bit more than 2 stops and re-tested. I forced the lens to minimum focus distance, then used the “AF-ON” button assignment to re-focus between every shot. Take a look at my MTF Mapper Cliff's Notes article on how to perform focus calibration using a proper focus chart and software that can provide definitive answers about if you're in focus or not. First Test: Focus Fine-Tune is OFF f/1.8 Lens Center MTF50 lp/mm Measurements 32 34 32 36 34 f/4.0 Lens Center MTF50 lp/mm Measurements 65 70 70 70 70 Second Test: Focus Fine-Tune is ON (+7) f/1.8 Lens Center MTF50 lp/mm Measurements 50 50 50 50 50 f/4.0 Lens Center MTF50 lp/mm Measurements 70 70 70 70 70 The average f/1.8 MTF50 lens center resolution with no focus fine-tune was 33.6 lp/mm. The average f/1.8 MTF50 lens center resolution with focus fine-tune ON was 50 lp/mm. The average f/4.0 MTF50 lens center resolution with no focus fine-tune was 69 lp/mm. The average f/4.0 MTF50 lens center resolution with focus fine-tune ON was 70 lp/mm. At maximum aperture, the resolution change using fine-tune calibration was HUGE (it went from 33.6 to 50). With the lens stopped down, the resolution change was minimal. So there you have it. If you camera doesn’t have focus fine-tune, then get one if you can afford it. Or else buy Sigma lenses that support their USB calibration dock for in-lens calibration. If you only shoot lenses stopped down, then you can probably safely ignore focus calibration. #howto

This review mostly details the lens MTF50 resolution performance and how well the lens auto-focuses. I don’t need to rehash the Nikon specifications of the lens. Is it just me, or does that lens title seem like all it’s missing is “EIEIO”? You can pick up this lens for dirt cheap, so bear that in mind if you notice any whining in the subsequent paragraphs about things that only exist on pricier lenses. The lens feels like it weighs nothing, and it’s really short for being able to zoom to 200mm. It has a good solid (plastic) bayonet lens shade that will reverse-mount on the lens for really compact storage. It telescopes out as you zoom to 200mm. The lens has a plastic lens mount and no rubber seal. What a shocker ;~) Focus This and the 18-55 kit lens are the only AF-S Nikkors I’m aware of that you can’t override auto-focus with the focus ring. You have to switch the lens to “manual” focus. Yuck. The skinny plastic focus ring is right behind the 52mm filter. Double yuck. If you can stick to auto-focus, though, it’s no problemo. There is no focus scale. Did I say yuck yet? The auto-focus DOESN’T have any chatter. Yay! Beats that evil 70-300 zoom. Speaking of auto-focus, this lens is unfortunately the poorest example I’ve seen from Nikon. It’s slow, and even refused to operate in “cloudy bright” conditions when I tried Live View at f/8.0 on the D7100. The 18-55 kit lens focuses much better. Stick to phase-detect focus. At least it didn’t have any focus chatter. Or did I already mention that? Nikkor 55-200mm zoomed out to 200mm with HB-37 hood Zooming out and using the hood makes it look like a much larger lens. When zoomed to 55mm and having the hood reverse-mounted, it stores away in a really small space. Vibration Reduction (VR) This version of the lens has VR; the original version didn’t. I was able (sticking to decaf) to get about half of my shots sharp at 1/100s with NO VR while zoomed to 200mm. Using VR, I could go to roughly 1/50s. I even got one sharp shot (out of 5) at 1/13s with VR ON. If the rule of thumb is 1/(35mm focal length equivalent) limit, or 1/300s then you could say the VR is good for about 2.5 stops. Everybody is different in how they support the camera while hand-holding it, so your mileage will vary here. I determine “sharp” versus “un-sharp” by photographing a resolution chart at slow shutter speeds and measure where the resolution (MTF50 lp/mm) drops by about 10% from maximum. I don’t know if there is some industry standard on VR effectiveness, but what counts for me is when pictures just start to show some blur, and I like to do it by the numbers. I haven’t figured out how to calibrate my level of nervousness with hand-holding, so this VR business is literally “hand waving”. Oh, also, I test at the longest focal length (200mm). Resolution Testing This review is looking at a single copy of the lens. Yours will be different, but hopefully ‘similar’. These tests were done using a Nikon D7100 (24 MP) with unsharpened 14-bit compressed RAW format. Resolution is a 2-dimensional thing. The tests that follow show you how resolution varies throughout the frame. If you ignore the corners, then resolution is really quite good. About time I said something positive about this lens, isn’t it? Also, the sagittal direction is really, really good. The meridional direction, on the other hand, is really quite terrible and is the culprit in dragging down the MTF50 numbers. I have a few shots below that demonstrate what I’m talking about. You’d swear there was severe motion blur in the pictures, but it’s just the meridional direction optical aberrations. 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 my MTF Mapper Cliff’s Notes article. The software is comparable to ‘Imatest’ in the quality of the MTF measurements, and it uses the “slanted edge” technology similar to ‘Imatest’, also. I can’t thank the author of MTF Mapper, Frans van den Bergh, enough. 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. If you spot some small islands of resolution peaks/dips in the following charts, you can safely ignore them. Visually imperceptible variations in the surface of the resolution chart can show up rather dramatically in the plots, because the analysis software is exquisitely sensitive. 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 auto-focus (where possible), contrast detect, IR remote, VR OFF, and a really big tripod. For f/8 and beyond, I was forced to use manual focus using Live View at 100%, since it refused to focus automatically. 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. 55mm f/4.0 APS-C Corner. Note Sagittal is MUCH better than Meridional The corner at 55mm f/4.0 shows how much worse the meridional direction is than the sagittal direction. Also note the vignetting (I don’t care much about vignetting, since it’s easy to fix in post processing). There is very slight chromatic aberration (this is the unmanipulated RAW view), which is also trivial to fix in post. 55mm f/4.0 center looks good 200mm f/5.6 corner. Good unless you count the meridional direction! Lens center 200mm f/5.6. Unusually poor dead center, but much better resolution just a little off of center. See 2D plots below for overall resolution view. Conclusions While not in the ‘pro’ category, this lens is still capable of producing some fine photographs, even wide open. If you can tolerate f/11, it’s capable of truly good shots. It’s all about knowing a lens strengths and weaknesses. For 200mm, it’s exceptionally portable and light. You can’t beat the price. I’d avoid low light levels; without a distance scale, even manual focus can be a challenge. The picture below gives you a hint of what the lens is capable of doing with a bit of practice. Sample Picture Rabbit at a dead run, 1/500s f/5.6 55-200mm at 200mm, ISO 400, VR ON, 37 feet. Very few shots require sharp corners. This shot has always been a favorite of mine, done with one of the cheapest and least glamorous lenses that Nikon makes. It looks quite sharp, even in a print I have that’s 36 inches wide. It was taken by my daughter, who got her amazingly fast reflexes by competing in fencing (foils) competitions for years. Try shooting wild rabbits on the run and you’ll appreciate the shot even more. #review

This review will emphasize the lens MTF50 resolution performance and how well the lens auto-focuses. I was feeling guilty about not writing a review of what is probably the most populous Nikon lens of the modern age. So here it is. The lens is so light that it feels like it’s filled with helium. It’s supplied with a lens cap and an end cap and … nothing. The lens has a plastic lens mount and no rubber seal. Exactly as you’d expect. So what DOES this lens have? It has resolution. And it’s my go-to lens for infrared. Large, quality infrared filters are devilishly expensive, so the 52mm filter threads on this lens are a welcome sight. Focus This lens won’t let you override auto-focus with the focus ring, which I used to think was a ‘given’ with AF-S. Wrong. You have to switch the lens to “manual” focus. Major complaint here. The auto-focus fine-tune on this lens is ZERO at 55mm, but it’s -4 at 18mm (these numbers are for my D7100, but different on the D7000). Since this isn’t a Sigma lens with the ability to fine-tune at various focal lengths and distances, I’m kind of stuck unless I stop the lens down to f/8 or so. I decided to split the difference and set the fine-tune on -2. The skinny plastic focus ring is right behind the 52mm filter. There is no focus scale. Given this meager working set, it can be tricky to manage getting the lens focused, keep the focus ring steady, and screw on an infrared filter. The auto-focus DOESN’T have any chatter using my usual AF-C and rear focus button. Yay! Speaking of auto-focus, this lens is more in the ‘turtle’ category than the ‘rabbit’ category. At least it eventually gets there. I exaggerate, of course. Nikkor 18-55mm on the D7000. Using my classic (1974!) L39 filter. Get a load of that world-record-skinny focus ring knurling behind the filter! Speaking of the filter, it’s not one you’d want to point toward the sun. It’s uncoated, but it has been my friend most of my life and I could never get rid of it. Vibration Reduction (VR) This version of the lens has VR; the original version didn’t. Newer versions now have “VRII”. I was able to get about 2.5 stops of anti-shake, but my results vary a lot. Everybody is different in how they support the camera while hand-holding it, so any quote about VR effectiveness isn’t really a rule; it’s more of a guideline. Yes, that line was stolen from Jack Sparrow. Resolution Testing This review is looking at a single copy of the lens. Yours will be different, but hopefully ‘similar’. Some day I might get around to testing more of these things, since I have a few more laying around. These tests were done using a Nikon D7100 (24 MP) with unsharpened 14-bit compressed RAW format. Resolution is a 2-dimensional thing. The tests that follow show you how resolution varies throughout the frame. The resolution charts are split into “sagittal” direction (like wheel spokes) and “meridional” directions. These directions match the MTF references published by Nikon. What’s different, though, is the following values were MEASURED versus Nikon’s “theoretical” values. Also, the sagittal direction is quite good. The meridional direction isn’t nearly as good and is the culprit in dragging down the MTF50 numbers. I use a (free!) program called MTF Mapper from here to measure lens resolution. The download site also includes files for printing out the resolution targets (mine are A0 size on heavy glossy paper, dry-mounted onto a board). This program is covered in more detail in my MTF Mapper Cliff’s Notes article. The software is 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, provides this excellent software for FREE. Visit his site and give him the praise he so richly 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, except in the most expensive of optics. If you spot some small islands of resolution peaks/dips in the following charts, you can safely ignore them. Visually imperceptible variations in the surface of the resolution chart can show up rather dramatically in the plots, because the analysis software is exquisitely sensitive. 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 auto-focus, contrast detect, IR remote (via a cell phone), VR OFF, and a really big tripod. 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. Corner at 18mm f/3.5 Center at 18mm f/3.5 Conclusions While definitely not a ‘pro’ lens, this lens is still capable of producing some fine photographs, even wide open. You can’t beat the price. Without a distance scale, even manual focus can be a challenge. With my copy, the longer focal lengths are the weakest (typical of almost all zooms, by the way). Corners aren’t stellar, but surprisingly good. The center is really good at all focal lengths; nothing to complain about here. My own style dictates that I use this lens at 18mm maybe 90% of the time. Luckily, it has great optical performance at that length. Sample Pictures 18mm f/10 Hoya R72 (Infrared) with Red/Blue color channel swap Sequoia 18mm HDR using Efex Pro2 HDR. Some chromatic aberrations visible #review

This is a pre-AI model, and was tested on the D5000, which Nikon specifically states is incompatible with this camera. Hmm. This lens was the reason many people bought Nikon. In its day, it was the portrait lens to get. I remember Linda McCartney using this lens to take pictures of Paul in a televised concert. It’s my understanding that she could afford to use whatever gear she wanted, seeing as her husband was already a near-billionaire at the time. This lens version had anti-reflection coating (the "C" in the lens designation). This is another lens that was used in the making of the original Star Wars movies. The MTF50 measurements presented below, being produced from a 12MP camera, don’t look as high as more modern high-resolution sensors. This lens won’t fit my other cameras, and isn’t one that can be updated to “AI”, either. Focus Silky smooth, but totally manual. When you could get cameras with split-prism focusing screens, focus was a breeze. With cameras these days, manual focusing is a lot tougher. Such is progress. I had thought the D5000 “rangefinder focus” would be the answer, but it won’t work for these manual lenses. Oh well. Nikkor-P C 105mm f/2.5 with HS-4 hood on D5000. An elegant lens. Resolution Testing These tests were done using a Nikon D5000 (12 MP) with unsharpened RAW format. Resolution is a 2-dimensional thing. The tests that follow show you how resolution varies throughout the frame. Also, the sagittal direction is really, really good. The meridional direction isn’t as good, but is still better than most lenses. 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 my MTF Mapper Cliff’s Notes article. The software is comparable to ‘Imatest’ in the quality of the MTF measurements, and it uses the “slanted edge” technology similar to ‘Imatest’, also. I can’t thank the author of MTF Mapper, Frans van den Bergh, enough. 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. If you spot some small islands of resolution peaks/dips in the following charts, you can safely ignore them. Visually imperceptible variations in the surface of the resolution chart can show up rather dramatically in the plots, because the analysis software is exquisitely sensitive. 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 “Live View” manual focus at maximum magnification and IR remote. I use the “best of 10 shots”; not every shot gets the same resolution results. Corner, wide open at f/2.5 target squares cycles/pixel. Sagittal beats meridional. Center, wide open at f/2.5 target squares cycles/pixel. The corners aren’t really good until f/4.0, but the center is terrific at all apertures until a little beyond f/16. You don’t want to use f/16 or beyond if resolution is important to you. Diffraction kills sharpness. I didn’t bother to measure, although this lens lets you set the aperture all the way down to f/32. The resolution of this lens leaves almost nothing to complain about. The corners, which are a “don’t care” nearly all of the time for most people, need f/4.0 or more. Conclusions If you’re a “manual” kind of person who likes to be in charge of what is going on, then this just might be the “it” lens for you. Bear in mind that the lens mount doesn’t permit being mounted on the latest Nikons, and this version cannot be “AI converted”. I have always enjoyed using this lens for portraits, and it gives you enough working room that your subject is invariably more at ease. You can’t exactly quantify it, but this lens just feels right. Sample Picture Crop from a head shot. The eyes tell the story of this lens. #review

It might seem shocking at first to see that your full-frame camera can have poorer lens resolution scores than the cheapo APS-C sensor. Here’s what is probably going on. Your small-frame sensor probably has smaller pixels than that full-frame camera does. Smaller pixels means more pixels per millimeter on the sensor, and hence more lines per millimeter, too. Here’s a specific example. Let’s compare the D7100 to the D610. Both cameras are roughly 24MP, so you’d think that they would score about the same. D7100 4000 X 6000 pixels, and has dimensions of 3.92 microns for each pixel. The D7100 sensor itself is 15.6 mm X 23.6 mm. D610 4016 X 6016 pixels, with 5.95 micron pixels and is 24.0 mm X 35.9mm. Let’s look at some resolution measurements, using the same lens at the same f/stop. Here, I’m using the Sigma 150-600 at 600mm, f/6.3. D7100 with Sigma 150-600 at 600mm f/6.3 tops out at MTF50 of 40 lp/mm D610 with Sigma 150-600 at 600mm f/6.3 tops out at MTF50 of 34 lp/mm Did I get ripped off?? Why is the resolution so much worse with the D610 compared to the D7100? The secret lies in the pixels. There are less pixels per millimeter in the D610, and therefore less MTF50 lp/mm resolution. But there are more millimeters in the D610 sensor! The key measurement of interest here is in line pairs per picture height (lp/ph). The math: lp/ph = lp/mm * mm_of_height The D7100 sensor height is 15.6 mm. The D610 sensor height is 24.0 mm. For the above measurements, the D7100 measures 40 lp/mm * 15.6 mm = 624 lp/ph The D610 measures 34 lp/mm * 24.0 = 816 lp/ph. So, the D610 wins after all. It has a ‘score’ of 816 and the D7100 has a ‘score’ of 624. More total lines of resolution in the photo for the D610. But wait, there's more: D610 pixel area = 35.4 square microns D7100 pixel area = 15.4 square microns This means that the D610 pixels can drink up more than twice the light per pixel, which makes for vastly superior low-light and high-ISO abilities. You can also achieve narrower depth of focus with the full-frame sensor, so you have more options photographically. Feel better now? #howto

This is a basic test to perform before the return date expires on your new lens. Keep this test in mind if you ever accidentally give your lens a hard bump, too. This idea comes from Roger Cicala at this link: It’s cheap and easy to perform. The trick is to get your photos properly out-of-focus. I never thought I would give anybody that kind of advice. Also, you’ll want to under-expose your shot, since camera meters aren’t very smart about subjects like this. Use notebook paper reinforcing rings stuck onto black construction paper. What you want is to get an idea of how the corners differ from the center and from each other. I fortunately don’t have any lenses with gross de-centering, so my shots show nice symmetric fuzzy circles. According to Roger, there are very few lenses (some super-wides and mega-zooms) that might give a false-positive bad result. It’s not important if your shots are out of focus in front of or behind the rings. What you do want is for the middle of the rings to still show just a little black. The following shots demonstrate an 85mm lens and a 600mm lens test. 85mm lens f/1.4 Len Centering Chart properly out-of-focus 600mm f/6.3 All circles are boringly perfectly circular. Look for circle characteristics that aren’t symmetrical; depending upon your lens, it’s expected that the corners won’t look exactly like the center, but each corner should demonstrate similar characteristics to the other corners. Chart too out of focus. Centers have gone from black to white. I prefer to shoot lenses wide-open for these tests, which will tend to magnify any lens faults. There you have it. An easy, inexpensive lens-screening test. Remember this test when you buy your next lens to give it a quick once-over. May your circles be symmetric. #howto

Many of you are aware that you can use the beloved 35mm f/1.8 DX lens with an FX sensor. I have an on-going love affair with this lens, but if anybody mentions it to my wife, I’ll flat-out deny it. There are many discussions about the ‘vignetting’ levels when you try this lens on FX, but there is precious little data on the “corner sharpness” when you decide to misuse/abuse this lens by mounting it on an FX body. Not to mention how the focusing distance affects vignetting. This article explores the practicality of using the 35mm f/1.8 DX lens with an FX sensor. The news is good. You don’t need to abandon what (to many) is their absolute favorite DX lens that Nikon produces. The coverage (the image circle) of the 35mm f/1.8 DX shows how this lens is an over-achiever. It goes above and beyond what is required for a DX sensor; it’s almost as if Nikon designed this lens for FX, but accidentally labeled it as “DX” instead. Almost. To be honest, the corners do get a bit dark, especially when the lens is focused near infinity. The secret sauce is to use the “vignette control” in image-editing software to lighten corners, and to not stop down the lens too much. The post-processing solution isn’t perfect, but for many photographs, it will make it turn vignetting into a “don’t care” situation. Believe it or not, the corner resolution isn’t that bad, either. It’s not as good as an “FX” lens, but most people won’t even notice the difference between this “DX” lens and an “FX” equivalent. At a fraction of the cost and a fraction of the size and a fraction of the weight. The bottom line, assuming that you want to be able to focus at infinity, is to keep your lens between f/1.8 and f/4.0. This isn’t much of a hardship. If you want to stop down further, then yes, you’ll need to crop a bit, but only just a bit. 35mm f/1.8 AF-S DX mounted on an FX Nikon D610 Since talk is cheap, let’s look at the data. Nikkor 35mm AF-S DX at f/1.8, with no distortion correction, using Nikon D610. You can barely make out any vignetting in the resolution chart (4.6 feet away). The vignetting was corrected using Capture NX2, but the correction is almost identical using other tools, like Photoshop. You can tell there’s some barrel distortion, though, so let’s try to fix that next. Nikkor 35mm AF-S DX at f/1.8, barrel distortion removed, Nikon D610. Now, there’s no visible distortion and any vignetting is almost gone. For normal photography, you’d not notice any vignetting. Nikkor 35mm AF-S DX at f/4.0, vignetting/barrel distortion removed, Nikon D610. Note that vignetting is still almost imperceptible at f/4.0, and I’ll bet nobody would be complaining about edge sharpness, either. You can even get away with f/5.6 and not have vignetting trouble, unless you try to focus at a long distance. I'd say that the vignetting here is about the same as the Nikkor 18-140mm AF-S DX lens on a DX camera. Nikkor 35mm AF-S DX at f/1.8, focus near infinity, Nikon D610. No free lunch. Now, it’s time to look at some warts. The picture above was focused near infinity, and the lens had both a hood and a UV filter on it. Cropping is becoming a necessity under these conditions, but the angle of view after cropping still far exceeds the Nikon in-camera “automatic DX cropping” that the camera offers. Using a UV filter and a hood don’t make a perceptible difference with vignetting; the lens image circle is the limiting factor. Resolution So, how does the resolution at the FX frame edges stack up? The following charts tell all. MTF50 lp/mm at f/1.8. The center, of course is already terrific. Corners aren’t. MTF50 lp/mm at f/2.8. The center is very, very good. Corners still aren’t. MTF50 lp/mm at f/4.0. The center is stellar. Corners are now acceptable. Conclusion With only a few concessions, this lens is quite useable on FX. Speaking for myself, it’s a keeper for either DX or FX. #review

It’s well-known that the Tokina 11-16mm f/2.8 DX will work on an FX camera. What isn’t well-known is the corner resolution performance on FX. This discussion is valid for both the original “Pro DX” and the “Pro DX II” AF-S versions, which have the same optical formula. See my original review of this lens (on DX, of course) here. Did you know that you get nearly zero vignetting at 16mm on FX, or that this is actually a wider angle of view (16mm FX) than you can get on your DX camera at 11mm? Your DX camera only sees the equivalent of 16.5mm on an FX camera while zoomed to 11mm on DX (a Nikon DX camera, that is). The Nikon DX has a 1.5X crop factor, so (1.5 * 11) = 16.5. Many people have said that the Tokina is usable in the 15mm-16mm range, but that’s not what my testing shows. 15mm starts to show vignetting, so I personally wouldn’t use the 15mm focal length. I just treat the Tokina as a “16mm prime” when mounted on an FX body. This lens isn’t sensitive to the focus distance causing a change in the amount of vignetting, so you don’t have to worry about that. I’m even able to use a “thin” UV filter and the lens hood while at 16mm on FX. Tokina 11-16mm f/2.8 DX lens mounted on the Nikon D610 FX camera First, let’s use an A0-size resolution target to evaluate resolution. I use the MTF Mapper software to evaluate resolution, and this is a picture of the resolution target designed for it. Tokina un-corrected resolution taget at 16mm f/2.8 shows minimal vignetting. Tokina corrected resolution taget at 16mm f/2.8 shows minimal distortion. Tokina at 16mm f/2.8 center resolution is already good, but corners are well behind. f/4.0 center is excellent, but corners still aren’t much improved f/5.6 shows pro-level center performance. Corners are still a bit weak. \ f/8.0 This is the best overall performance aperture setting f/11.0 Still very good overall performance. Some diffraction is setting in. Tokina at 16mm, focused at infinity. Corners have no vignetting problems Tokina at 16mm. Excellent edge-to-edge. Distortion is minimal. Conclusion Honestly, you wouldn’t know that Tokina didn’t make this lens for FX, as long as you park it on 16mm. Vignetting, resolution, and distortion are all well-controlled. I can say without any hesitation that this lens is fantastic for use on both DX and FX cameras. #review

You may have already read my article about using manual mode with your external flash, which allows you to shoot in “manual” mode but get automatic exposure via the flash. That article can be found here. That particular mode of operation is for when you have a fixed ISO setting, which is the normal case while using "manual" mode. What about manual mode without flash? It turns out that you can still get ‘manual mode’ to provide automatic exposure. You make this happen by selecting “Auto ISO sensitivity ON” in the “Shooting” menu (on Nikons, of course). You can see this mode at work in Manual by adjusting the shutter speed or aperture and observing the ISO indicator value changing to keep up with your selections. When you attempt to set your exposure to go beyond your maximum ISO limit you have set, you’ll see the exposure indicator show "under exposure" (and by how much) since it won’t go beyond your specified maximum ISO limit. Why on earth would you want to automate Manual Mode? If you’re using a long lens, it’s handy to be able to set a specific aperture and also force a (specific) high shutter speed. If you hate to give up automatic exposure just because you want to specify both an aperture and shutter at the same time, this is the secret sauce that lets you have your cake and eat it, too. I guess I must be getting hungry; that’s too many food references to ever put into a paragraph, let alone a single sentence. If you’re worried about getting quality results (and you should be) then you may not want to use this technique unless you have a camera with a sensor that can handle pretty high ISO values without getting excessive noise. I have had far more shots ruined by motion blur than I have lost due to image noise. If you have a long lens (e.g. 500mm or beyond) then there’s basically no such thing as too fast of a shutter speed to capture fast-moving subjects. To calibrate your “Auto ISO”, do some testing up front to determine what’s a reasonable upper-limit ISO. Two key points to consider here are color noise and loss of dynamic range. I always assume that I’m going to be doing some post-processing of my (RAW) shots anyway, so a small amount of color noise in the un-processed shot is completely acceptable. The upper limit of color noise should be where you can no longer clean it up in your image editor without excessive loss of resolution. You should consider noise reduction that only operates on the colors and not the ‘luminance’ channel; you will retain resolution but the image will have a slightly sandy-grained look. A camera like the D610 is still coasting with values like ISO 4000, but a camera like my D7000 is already a little short of breath at ISO 1600. Dynamic range goes out the window with high ISO; don’t use a technique like the one presented here for something like landscape shots, unless you’re forcing a particularly slow shutter speed. Some camera models offer “Minimum shutter speed = Auto”, where the camera will select the “1/focal length” in the “ISO sensitivity settings” menu (with additional adjustment options to get values like 1/(focal length * 2) ). I find that this type of shutter speed control is fine for static subjects, but is often unsuitable for fast subjects like flying birds or action sports. I’d rather crank up the shutter speed to cryogenic levels and leave it at subject-freezing speeds. This technique is, of course, not appropriate in all situations. As always, pick the right tool for the right job. #howto

I happened to be testing an old Nikkor 20mm f/4 (AI-converted). I thought I’d try some infrared shots, since this lens is supposed to be excellent shooting IR. I use the Hoya R72 IR filter, with the 52mm thread diameter. This 20mm lens is about the smallest and lightest FX lens Nikon ever made. 7.4 ounces light. The D7000, D7100, and D610 allow aperture-priority auto-exposure after defining the “non-CPU lens data” for this lens. I absolutely love its field of view (94 degrees) on the D610. You’d never miss auto-focus using a lens like this, since everything is typically in focus all the time. You still get the 3-stage focus indicator inside the viewfinder while manually focusing. Still, 20mm on a DX camera isn’t that wide; my Tokina 11-16mm f/2.8 has no reason to feel threatened here. The 20mm, of course, has the little red dot on the focus scale for infrared focus compensation. Back in the day, Nikon really paid attention to stuff like that. Manual-focus lenses are actually superior to auto-focus lenses for shooting infrared with a filter like the Hoya R72, since you can’t see through the viewfinder. You frame and focus (and use the lens focus scale red-dot IR shift) before attaching the filter. Those of you who have gone through the pain of framing/pre-focusing a ‘G’ auto-focus lens and then mounting an IR filter know what I’m talking about. After all of those digressions, back to the subject at hand: IR shooting comparisons. The D7000 IR results indeed look excellent. Absolutely nothing to complain about here, aside from the gripe about the narrower DX field of view. I was shooting at f/11.0, 15 seconds, ISO 250. (“Sunny 16” rule would have been 1/500 at f/11, ISO 250. IR needed 12 stops more light!) Nikon D7000 using Hoya R72 with Nikkor 20mm f/4 AI-converted lens. Excellent Now, for the D610 infrared results. How to describe what I got? Epic failure comes to mind. Totally unusable. It appears that the light baffling and anti-reflection coatings inside the D610 act more like a mirror in the infrared spectrum. In comparison, this 20mm lens is wonderful for regular-light photography on the D610, especially for landscapes. Nikon D610, Hoya R72, Nikkor 20mm f/4 AI-converted lens. Gross. Next, I head for my D7100. Terrible. Exact same light baffling and anti-reflection coating problem in infrared. Nikon D7100, Hoya R72, Nikkor 20mm f/4 AI-converted lens. Gag me. Note the terrible horizontal glare across the entire frame for both the D610 and D7100. The Nikon D7100 misbehaves in a nearly identical way to the D610 when shooting infrared. My guess is that the camera internal baffling and anti-reflection coatings actually reflect instead of absorb infrared wavelengths. Ahh. I bet it's something wrong with the 20mm lens, you say. I bet the problem goes away with a different lens, you say. There's no way the D610 and D7100 could let me down this badly, you say. How could the D7000 possibly be superior to the D610 and D7100 in any way, you say. I tried using the 50mm f/1.8 AF-D with the Hoya R72 IR filter on the D610, since I’m apparently a glutton for punishment. Big nasty hot spot in the center of the picture, in addition to the terrible horizontal banding flare. Having used this lens in the past for infrared, I know it’s not the lens’ fault. I have to conclude that the D610 is useless for infrared photography. I didn’t have the heart to try this same lens on the D7100; I know the results would be the same. Now, the secret sauce to making the D7100 and D610 succeed with IR photography: you absolutely need to cover the viewfinder eyepiece with the little "DK-5" eyepiece blocker. Unlike the D7000, D60, D50, and D500 cameras I have tested, the light baffing in the D7100 and D610 seems to be inferior. You can clip the DK-5 onto your camera strap so you don't lose it, and you don't even need to take it off of the strap to slip it over your viewfinder! 50mm f/1.8 AF-D on the D610, HoyaR72 filter. Still gross and unacceptable. The Nikon D7000, as with all modern digital cameras, (that haven’t been converted to infrared) is very insensitive to infrared. The filter on top of the image sensor screens out almost all of the infrared wavelengths. Older camera sensor filters (like the D50 and D60) were much better at passing IR (a few stops better, at least). Aside from long exposure times, the D7000 provides top-notch IR results. Just keep in mind that the Bayer sensor only has a quarter of the photo sites sensitive to red, so your camera resolution is essentially divided by 4 as well. Nikkor 20mm f/4.0 AI-converted, on a D610. It's only a little bigger than a body cap. Moral of the story: don’t ditch that D7000 if you do infrared photography. For the D610 and D7100 (and probably the d7200), always use the little DK-5 viewfinder eyepiece blocker. By the way, I typically use Nikon Capture NX2 to convert my 'deep red' RAW shots into the samples you see above. I can't get the D7000 to succeed at measuring a scene to get "preset manual" white balance with infrared, although the preset measurement works for a D50 and D60. I use the Capture NX2 "Camera Settings", "White Balance", "Set Gray Point", "Marquee Sample", "Start", then rectangle-mouse-select the whole picture, then click inside the selection. This is a quick and easy way to get the picture really close to what the in-camera "preset manual" white balance procedure achieves for regular photography. Once the editing steps are entered, just save those steps as a batch process. The batch process can be run on a whole folder of IR shots, to quickly get everything converted. #review

This article is an evaluation of the old manual focus 20mm f/4.0 lens that has been AI-converted. The conversion makes it possible to get automatic exposure on the better Nikon digital cameras, including the D610 with an FX sensor. The 20mm f/4 was manufactured from 1974 through 1978, back when Nikon was the big man on campus in photography. Mine was purchased in 1975, and virtually never came off of my Nikon F2 when I was back-packing (unless I did some macro shots). Small, light, sharp, tough, elegant, and wide; almost exactly like the ideal woman, except perhaps for the ‘wide’ part. This 20mm lens is one of the smallest and lightest FX lenses Nikon ever made. At 7.4 ounces, you hardly notice it’s there. It's about 1.4 inches long, like a thick body cap. Cameras like the D7000 series and D610 allow aperture-priority auto-exposure after defining the “non-CPU lens data” for this lens. I absolutely love its field of view (94 degrees) on the D610. The lack of auto-focus using a lens like this isn’t a hardship, since everything is typically in focus all the time. You still get the 3-stage focus indicator inside the viewfinder while manually focusing with the better Nikons. The 20mm, of course, has the little red dot on the focus scale for infrared focus compensation. Back in the day, Nikon really paid attention to stuff like that. One of my main uses for this lens is infrared, but unfortunately cameras like the D7100 and D610 are essentially useless for infrared (see this article: ). My D7000, however, works perfectly for infrared with this lens (using the Hoya R72 52mm filter). Manual-focus lenses are actually superior to auto-focus lenses for shooting infrared with a filter like the Hoya R72, since you can’t see through the viewfinder. You frame and focus (and use the lens focus scale red-dot IR shift) before attaching the filter. Those of you who have gone through the pain of framing/pre-focusing a ‘G’ auto-focus lens and then mounting an IR filter know what I’m talking about. Focusing is still silky-smooth, unchanged since the day it was manufactured. The focus scale is a thing of beauty. I have every reason to believe that this lens will last not just a lifetime, but multiple lifetimes. Although it works without vignetting, be careful using a polarizer on this lens; the sky will look too un-even because of the wide field of view. 20mm f/4 Nikkor AI-converted on the D610. Sweet. Resolution Tests I test lenses using the MTF Mapper software and the recommended resolution charts (printed to A0 size and dry-mounted). The article here explains the software and its use. As you’ll see, you are going to want to stop down to f/8 or more to get the corners you want. The center is already very good at f/5.6, and only gets better as you stop down. Avoid going beyond f/16, because of diffraction. All tests were done using the D610, with 24 MP (5.95 micron pixels). I only shoot un-sharpened RAW for the resolution tests. To convert the MTF50 lp/mm measurements into LP/PH, simply multiply readings by 24.0. To convert into LW/PH, take the LP/PH values and multiply by 2. Sample Photos Sun just out of frame. Palm fronds near frame edge are sharp, D610. The “wavy” distortion is quite minimal, D610. Infrared, Hoya R72, D7000 Conclusion If you're willing to stop this lens down to f/8 or f/11, the results are about as good as any ultra-wide lens made today. You won't find a more compact lens anywhere. I love that it uses 52mm filters, too. This has become my go-to lens for infrared photography. My D610 and D7100, by the way, are basically useless for IR unless I put the DK-5 eyepiece cap over the viewfinder. My other cameras are fine without the cap, unless I switch to my 850nm IR filter, which requires exposures of 2 or 3 minutes; all cameras need an eyepiece cap when exposures get that long. I understand that this lens is a bit rare these days; I have no intentions of ever selling mine. #review