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03-06-2010, 05:07 AM   #1
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Join Date: Feb 2010
Location: thailand
Posts: 45
sigma 300mm f2.8 problems

I just bought a new sigma 300 mm f2.8 lens and the 1.4 and 2.0 converters.
The problem is the lens at 300mm is focusing bad. I can compensate for it in my settings but at +5 and +10. But sometime when close to the subject it is ok at 0.
I notice it really bad when i am photoshoping the photos. It is a huge difference.
Does anyone elese have the same problem or have you heard of the problem.

08-03-2010, 06:48 AM   #2
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Join Date: Aug 2008
Location: Wellington, New Zealand
Posts: 9,197
QuoteOriginally posted by gary1952 Quote
Does anyone elese have the same problem or have you heard of the problem.
It is a well-know fact that lenses show different FF (front focus) or BF (back focus) behaviour for different distances. I cannot say whether your copy behaves within a normal range.

What is your testing methodology?

Here are some AF adjustment hints.

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