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.
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.