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09-13-2009, 09:45 AM   #1
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Tokina AT-X SD 300mm f2.8 - problem with aperture selection

Hi there

I kave just bought a secondhand (clearly!) Tokina AT-X SD 300mm and am having a problem with it, both on my old K10D and new K-7. When leaving the aperture ring at "A", I can only select f5.6 as maximum open aperture on the camera. Manually selecting 2.8 on the ring, then looking at the photo info after shooting, it appears that it is actually 5.6 (as noted in the EXIF).

Question - when physically selecting 2.8 on the ring, am I actually shooting at 2.8, with the camera mireading the aperture from the lens, or is this lens only opening to 5.6 for some reason? I'm not using a TC or anything strange like that. Anyone come across this sort of problem before? The lens appears to be in very good condition, doesn't seem to be a physical problem. Off the camera, it opens all the way up to f2.8, no problems.

Thanks in advance for any advice!


09-13-2009, 12:05 PM   #2
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Standard advice would be to clean the electrical contacts on the lens and camera.
09-13-2009, 02:30 PM   #3
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Yep, clean the contacts. Camera "thinks" your lens is 5.6 max aperture probably because some contacts, after being stored for a while, might get dirty, and not conducting anymore.
09-17-2009, 10:13 AM   #4
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Original Poster
Great, thanks guys, will try this. Shouldn't be my shiny new K-7 at least Cheers, Paul


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