08-06-2011, 09:21 AM
[quote name='Beholder3' timestamp='1312621994' post='10421']
I am absolutely sure the autofocus hits better at f3.5+. In this apertura range I can't manage to get a better result with manual focussing and it's not a DOF issue. f1.8-2.8 I can easily get better results with MF.
It is always the same misfocus (with a little variance in amount).
It is backfocus (frontfocus at unlimited range would require an huge error and massive rewinding of the focus to focus on less than 15m (as the target is 220m away). That rewinding is not happening.
[/quote]
Then you are looking at a focus shift problem... as the AF gets done with the lens wide open. And those are usually by design, not a sample problem.
Is it in practical use a real problem, though? I can imagine that usually you have the need for bigger apertures with closer by subjects, and with far away subjects at 24mm you stop down past f3.5 anyway? So a problem that is easy to live with, just about understanding the intricacies of this particular lens?
I am absolutely sure the autofocus hits better at f3.5+. In this apertura range I can't manage to get a better result with manual focussing and it's not a DOF issue. f1.8-2.8 I can easily get better results with MF.
It is always the same misfocus (with a little variance in amount).
It is backfocus (frontfocus at unlimited range would require an huge error and massive rewinding of the focus to focus on less than 15m (as the target is 220m away). That rewinding is not happening.
[/quote]
Then you are looking at a focus shift problem... as the AF gets done with the lens wide open. And those are usually by design, not a sample problem.
Is it in practical use a real problem, though? I can imagine that usually you have the need for bigger apertures with closer by subjects, and with far away subjects at 24mm you stop down past f3.5 anyway? So a problem that is easy to live with, just about understanding the intricacies of this particular lens?