The Tokina AT-X M100 Pro D 100mm f/2.8 Macro Lens
by Don McVey

username: DWM
Nikonian in the USA

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PERFORMANCE

This lens shares a number of features with the Micro Nikkor 105mm. Not surprising considering the Tokina heritage. What I consider especially valuable in a macro lens is long throw of its manual focus. Like the Micro Nikkor 105mm, and more so than other macros I've looked at, there is plenty of travel in the macro range. This makes manual focus very easy and accurate. From 1:1 to 1:2 the travel is about 55 degrees. For better or worse, it also shares with the Nikkor the compressed focus travel from 3 feet to infinity. Use as a normal 100mm lens in manual focus mode becomes more of a challenge.

Image made with the Tokina AT-X M100 AF Pro D 100mm f/2.8 Macro lens

The good news is that auto focus works very well on this lens. Even inside in low light auto focus is pretty quick, especially for a macro lens. It is much faster than the longer focal length macros I tested. Although it’s a traditional screw focus lens it is reasonably quite and very accurate even at macro distances. Interestingly, it also focuses in the same direction as the Nikkors (and Pentax) in that infinity is on the far left, compared with Sigma and Tamron that have infinity at the far right (like Canon and Olympus). That is a small but pleasant plus.

Tokina has included a very effective focus limit switch that is easy to use. A large rotary switch is located on the left side of the lens. Twisting it a quarter turn will limit the focus range to either side of about 1:1.2 to 1:2.2, depending on which side of this spot you start on. Using the limit switch really helps when the lens does hunt in auto focus mode, although as I said above, it seems to hunt less that the longer macro lenses.

The effective aperture decreases on all macro lenses as you focus down from infinity to 1:1, usually by about two stops. The Tokina reports effective aperture to the camera as required for proper exposure, and also shows you the effective aperture in the EXIF data and on the camera display. At infinity focus you get the specified apertures of f/2.8 to f/32, but at 1:1 you end up with f/5.6 to f/64. This is what all macro lenses do, but they don’t all report the effective aperture even though as you focus down to 1:1 from infinity you can watch the exposure get longer as you turn the focusing ring. I prefer the effective aperture to be reported, as this lens and the Tamron 180mm do.

IMAGE QUALITY

This is ultimately where my decision to keep this lens was made. The sharpness and contrast of this lens are both excellent, and significantly better that the Tamron 180mm macro that I tested. Here are some comparison images of a section of a US one dollar bill that compare the Tokina 100mm, the Tamron 180mm, and about the sharpest lens I own, the 50mm f1.8 Nikkor. I haven’t included anything from the Sigma 150mm since I eliminated it from consideration early on due to some unexplained exposure issues.

The original image was taken with a Dollar Bill just filling the width of the frame. It was spray glued to a perfectly flat floor tile. Exposures were made using aperture priority on a Gitzo tripod with a Markins M10 ball head and a remote release. Lighting was my desk lamp and all were taken at the same session with only the tripod moving to keep consistent image size.

All images at right are approximately 200 x 133 pixels, normal sharpening, and auto white balance, shot in raw, cropped and converted to jpeg after opening with the Nikon plug-in for Photoshop CS. No adjustments of any sort were made. It's pretty clear which one has the most sharpness and contrast, even allowing for the slightly different color casts and exposure responses. What is surprising is how much better the Tokina is than the much more expensive SP AF 180mm f/3.5 Di LD (IF) 1:1 Macro Tamron. The normal caveat of lens testing applies here; individual lenses may not be representative due to manufacturing variances. I also took some shots of a fairly large spider in the garden. Shooting hand-held and using a SB-800 flash, reinforced my conclusions about the results shown above. Finally, I ran some resolution tests using the Imatest program that computes MTF data using a standard target ( www.imatest.com ). MTF is definitely not the whole story when judging lens quality. But, the results again confirm the image comparisons above and my observations.
	Nikkor 50mm f/1.8D AF @ f/16
	Tamron 180mm Macro @ f/16
	Tokina 100mm Pro D @ f/16

Below a chart showing the results at the center of the image of each lens. Images were converted to TIFF format at normal sharpening using Capture, then run through Imatest.

CONCLUSION

I'm impressed enough to keep this lens. After comparing it to several others, the Tokina really shines. I could have, of course, just bought the Micro Nikkor 105mm lens and been done with it. I initially didn't because I was looking for some longer working distance. I was also concerned about the bokeh of the Nikkor because it only has seven diaphragm blades and is generally considered a bit lacking in this area.

What I found was that this lens is effectively an updated version of the Tokina M100 previous model -which was very good as one may see here- and much closer to the Nikkor 105, including a nine blade diaphragm that I expect to produce very good bokeh. And when you choose not to use a lens hood, like you usually must on the longer telephotos, the effective working distance is not that much different than that of the longer lenses. At almost half the weight of the longer lenses it is much easier to handle. I also didn't mind saving about one third of the cost of the Nikkor. I expect to be very satisfied with my choice.