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Lens review

Tokina AT-X PRO DX 12-28 mm f/4

26 August 2013
Szymon Starczewski

8. Vignetting

We are going to have some fun, like in the test of the Tokina 11-16 mm II, and check what happens when a lens designed for smaller sensors is attached to a full frame camera. Appropriate thumbnails are presented below.

Tokina AT-X PRO DX 12-28 mm f/4 - Vignetting


As you can notice, up to 18 mm focal length the image circle of the lens is smaller than full frame and the corners are dark, no matter what aperture you employ. The situation starts to change near 20 mm. In that case, at the maximum relative aperture the vignetting amounts to only 33% (-1.13 EV) and such a value even on the smaller detector wouldn’t be considered high. On full frame it is an excellent result, especially if you take into account the real purpose of this lens.

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The 28 mm focal length is even better because by f/4.0 the vignetting gets to just 22% (-0.70 EV). Very interesting!

Do these excellent results help us in anything? Not really. At 20 mm and full frame you get the angle of view of less than 95 degrees. On the one hand it is a lot, on the other you can get more: if you attach the Tokina 12-28 mm to a reflex camera with an APS-C sensor you have almost 100 degrees of the field of view at 12 mm which is additionally corrected properly on the edges. You can’t say that much about 20 mm on full frame.

Let’s finish the fun and start serious testing on the APS-C/DX sensor the Tokina 12-28 mm was designed for.

Tokina AT-X PRO DX 12-28 mm f/4 - Vignetting


At the combination of the shortest focal length and the best aperture fastness you have to deal with the light fall-off of 36% (-1.28 EV). It is not a very high value but it isn’t also very low for this class of equipment. The vignetting decreases to 20% (-0.65 EV) by f/5.6 and to 12% (-0.37 EV) by f/8.0. By f/11 the problem ceases to exist because that aberration becomes almost imperceptible (10%).

At longer focal lengths the results are truly sensational. At 20 mm and by f/4.0 the vignetting amounts to 17% (-0.54 EV) and it becomes imperceptible by f/5.6 and f/8.0 where it is, respectively, 11% (-0.33 EV) and 7% (-0.20 EV). At the maximum focal length it is even better – by f/4.0 the vignetting reaches only 14% (-0.45 EV) and by f/5.6 it becomes invisible (9%).

Results in this category definitely deserve our praise. The Tokina fares better than its immediate competitors and also better than its predecessor with a narrower focal range. A round of applause for the constructors!

Tokina AT-X PRO DX 12-28 mm f/4 - Vignetting

Tokina AT-X PRO DX 12-28 mm f/4 - Vignetting

Tokina AT-X PRO DX 12-28 mm f/4 - Vignetting