I just realized my Tokina 12-24 showed inconsistent exposure: At the wide-end, it underexposed by about -0.5ev at smaller apertures (e.g. f/16). i.e. If I set it to 12mm, set the camera (D70) to A mode and spot meter, take a shot of a graycard @ f/4 and then take another shot @ f/16, the f/16 shot appears darker and has its histogram peak moved left.
- I don't think it's corner light fall-off. Otherwise, it would've been darker at the wide aperture because of darker corner.
- I went back to the shop from where I bought the lens and tried another sample. Same result.
- I talked to an experienced photographer. He told me it's not uncommon certain lens designs will result in minor inconsistent exposure at different apertures and +/-0.5ev is well within the acceptable tolerance.
- I asked a friend who owns the same lens to try his. His showed inconsistent exposure at the long-end, not the wide-end!
- I went to Tokina Service (i.e. Ricoh) and talked to a technician, the technician reckoned it could be the lens design as it only showed by at certain zoom settings, not all, but so far no customer had report similar problem.
- I asked about this on dpreview.com forum. But only a couple of people said they saw similar behaviour.
So, it's still inconclusive. Not sure it's a sample-to-sample calibration issue or it's a lens design issue affects all lenses. Although 0.5ev is not a huge inconsistency I can't live with, I still want to get rid of it if I can.
Could Tokina 12-24 owners please do some quick tests to see if you see similar behaviour? Thanks.
- I don't think it's corner light fall-off. Otherwise, it would've been darker at the wide aperture because of darker corner.
- I went back to the shop from where I bought the lens and tried another sample. Same result.
- I talked to an experienced photographer. He told me it's not uncommon certain lens designs will result in minor inconsistent exposure at different apertures and +/-0.5ev is well within the acceptable tolerance.
- I asked a friend who owns the same lens to try his. His showed inconsistent exposure at the long-end, not the wide-end!
- I went to Tokina Service (i.e. Ricoh) and talked to a technician, the technician reckoned it could be the lens design as it only showed by at certain zoom settings, not all, but so far no customer had report similar problem.
- I asked about this on dpreview.com forum. But only a couple of people said they saw similar behaviour.
So, it's still inconclusive. Not sure it's a sample-to-sample calibration issue or it's a lens design issue affects all lenses. Although 0.5ev is not a huge inconsistency I can't live with, I still want to get rid of it if I can.
Could Tokina 12-24 owners please do some quick tests to see if you see similar behaviour? Thanks.