Micro Nikkor 60mm AF-D Review
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.
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.
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.
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.
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.