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06-06-2009, 06:54 AM   #16
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QuoteOriginally posted by RollsUp Quote
I did re-read your post after posting the test images and I understand it. What I find puzzling is all my photos taken at 75mm f2.8 are very soft, awful would be a better word to describe them. None of them are anywhere near sharp, even up to f5.6.

I'm sending this lens back to Tamron tomorrow with sample images taken at f2.8, f5.6 and f8 along with the latest focus tests, and I hope that Tamron can adjust it so that I can start taking sharp images with it at f2.8.
I am sure they can IF you can prove that the problem isn't with the camera OR you send them the camera body along with it. I have two K20Ds. one has slight FF the other slight BF All of my lenses need different degree of correction on both bodies, but in opposite directions. As stated by others, the 28-75 does have a few "quirks" but the body is also (potentially) the problem. If you have two lenses, one of which is spot on, and the other BF/FF you can't know for sure whether the one that is clear is in proper focus because it and the body are perfect, or if it is because both are off by exactly the same amount in opposite directions. I had a Tamron 28-75, and to say I am not a fan of that lens is an understatement, but I am even less a fan of bodies that don't allow for focus correction.

Last edited by Parallax; 06-06-2009 at 08:17 AM.
06-06-2009, 04:10 PM   #17
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I had a similar issue with da40 and da70 with my k100d. Of course both lenses needed different levels of adjustment in the 'debug' menu. My body has a BF issue so the da40 needs +30 and the da70 needs +60. It's a pain to change lenses but i live with it (got a K7 on order to fix all that and I'll keep teh k100d as a manual focus toy for my tak, M and A lenses).

The awful thing about all of this is that sometimes a lens will focus within DOF and 2.8 (or max aperture) on a test chart but in real life it nearly always backfocuses. What is the point of payinf for 2.8 if you always use it at 5.6? Sure it is sharp as a tak at 5.6 but it's not really what you paid for.

Certainly with the pics above i would send it back.

Do you think in the digital era we are more 'testie' than on film. On film, who would tak 100 test shots just to check the lens? Is this why we are seeing price hikes? Because sooo many lenses get sent back. EG. the first da40 i had BF so much I could not correct it within the bounds of camera adjustment.

06-08-2009, 06:52 AM   #18
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Don't feel like the Lone Ranger and don't think this is unique to tamron. I recently sent a FA 28-105 back to Pentax that was doing exactly what your lens is doing. I tested mine on a k20d and an istdl with identical results. Pentax had the gall to tell me The lens was perfect and I should only use digital lenses on my Pentax digital bodies. I suggest that you send it back again and annoy them daily til they make it right or replace it.

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