06-06-2011, 07:55 PM
[quote name='wizoo' timestamp='1307358872' post='9054']
Hello everyone,
I'd like to share one problem, to see if this is just my sample, or it is a general issue.
I have a Canon 60D + Tamron 17-50 f/2.8 (the non-stabilised version): when I use contrast detection focus, @50 mm, the focusing is never accurate. It is like the autofocus is in "steps" (or jumps) too large to be really spot-on.
At other focal lengths, or with phase detection, everything is fine.
Anyone else experienced this?
Many thanks,
Davide
[/quote]
It is not uncommon for contrast detection to not be able to find focus correctly with certain lenses. The lenses simply do not make small enough steps to be able to "see" when contrast is best, and focus gets "declared" when the subject in fact is still out of focus.
My Sigma 18-50mm f2.8 has similar problems, and trying to focus with contrast detection with a Tokina 12-24mm f is gives ridiculous results (EOS 450D).
So, I guess what you are noticing is "normal", and has to do with the lens' electronics/motor.
Hello everyone,
I'd like to share one problem, to see if this is just my sample, or it is a general issue.
I have a Canon 60D + Tamron 17-50 f/2.8 (the non-stabilised version): when I use contrast detection focus, @50 mm, the focusing is never accurate. It is like the autofocus is in "steps" (or jumps) too large to be really spot-on.
At other focal lengths, or with phase detection, everything is fine.
Anyone else experienced this?
Many thanks,
Davide
[/quote]
It is not uncommon for contrast detection to not be able to find focus correctly with certain lenses. The lenses simply do not make small enough steps to be able to "see" when contrast is best, and focus gets "declared" when the subject in fact is still out of focus.
My Sigma 18-50mm f2.8 has similar problems, and trying to focus with contrast detection with a Tokina 12-24mm f is gives ridiculous results (EOS 450D).
So, I guess what you are noticing is "normal", and has to do with the lens' electronics/motor.