Tamron 17-50 f/2.8 focusing problem.

Started Dec 20, 2008 | Discussions thread
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antiq Junior Member • Posts: 27
Tamron 17-50 f/2.8 focusing problem.

Hello, dear photography geeks (I mean it in the best possible way).

My friend (who doesn't speak english very well) bough a used Tamron 17-50 f/2.8 for his Canon 350d and he's having the following problem:

At first, he simply noticed that some pictures were sharp, while others out of focus.

The usual focusing chart tests didn't confirm no back or front focus.

He decided to try some camera tweaking according to this tutorial (it's google-translated from english, but you get the idea from the pictures):

http://translate.google.com/translate?u=http://www.astrosurf.com/buil/autofocus/adjust.htm&langpair=fr |en&hl=en&ie=UTF-8&oe=UTF-8&prev= language_tools

He arrived at a point, where the focusing at 50mm is spot on, while the 17mm is completely OOF (seems like front focus) and the focal lengths in between are gradually worse.

Additional info:

  • We are talking about focusing problems, the lens seems to be good otherwise; I don't believe he mixes up lens softness and out of focus softness.

  • He claims he sees the target sharp after focus lock in the viewfinder, only the result is oof.

My question is: do you have any experience with similar problems, and is the camera or the lens to blame? (apart from his meddling of course;).

I tried to search for similar focal-length dependent focusing issues but no luck so far, in case I've missed something please accept my apology.

Thank you.

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