It’s reasonable to think that wide-angle lenses for SLRs will have lower color errors in the corners than similar lenses for rangefinder cameras. That’s because the greater flange distance in SLRs forces designers of lenses for those cameras to reverse-telephoto (aka retrofocus) designs, which move the nodal point further from the imaging plane. Move the nodal point out further and the angle that the light rays make with the sensor gets closer to ninety degrees.
So it was with high hopes that I tested a Zeiss 21mm Distagon f/2.8 ZF-2 (Nikon F mount) on the NEX-7. This lens has been a stellar performer on the Nikon D3x.
Here are the results:
| UR | LR | LL | UL | |
| L* | -14 | -12 | -6 | -8 |
| a* | 1 | 1 | -1 | 0 |
| b* | -1 | 3 | -6 | -3 |
| 1.4 | 3.2 | 6.1 | 3.0 |
Pretty good, except for the lower left corner, but a bit worse than the Leica Tri-Elmar at 21mm, which turned in these numbers.
| UR | LR | LL | UL | |
| L* | -9 | -9 | -8 | -8 |
| a* | 1 | 1 | 0 | 0 |
| b* | 0 | -2 | -5 | -3 |
| 1.0 | 2.2 | 5.0 | 3.0 |
Because of the lower left corner performance, the Distagon will require correction in most circumstances.
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