This article is nominally about Canyon autofocus accuracy but, except
for the specifics of the manufacturers statement of accuracy (to within
1/3 the depth of *focus*), it pertains to any focusing error be it
manual or auto. I'm sure that Oly's or any other manufacturer's
statement of autofocus accuracy will be found very similar to Canyon's.
In a nutshell, the autofocus limits of accuracy need to be reflected
in a much more restrictive Circle of Confusion (CoC) assumption used for
calculating depth of field.
<doug.kerr.home.att.net/pumpkin/AF_accuracy.pdf>
Chuck Norcutt
Moose wrote:
> Chuck Norcutt wrote:
>> Early adopters of the Canyon 20D had lots of complaints about focusing
>> errors. It's one of the reasons I didn't buy one right away and then
>> the 5D became available in the interim. But that faded away for reasons
>> unknown to me
> I suspect a relatively small number of cameras with a real problem got
> repaired and the pixel peeping madness fizzled out.
>
> AF is not perfect. Like DOF, it just needs to be close enough, which
> varies with use. I've noticed with complex subjects that putting the
> central point directly centered on the point I want to be the focal
> plane that I sometimes get instead something nearby, and slightly closer
> or further away. Generally, moving the focal point slightly and
> half-pressing again will do the trick in a try or two. With
> close-up/macro, sometimes it just needs MF.
>
> I find the ability to select AF AOV on the E-3 interesting. I wonder if
> it would be much use in practical field conditions.
>
> A perfectly accurate AF, when you located the AF point on your subjects
> eye, would ask you whether you wanted the focal plane at the nearest
> point of the roughly spherical object it detects, the deepest visible
> point of it, or at an average. Then it would want a discussion of the
> amount and desired direction of DOF.
>
> I don't think I could deal with that for regular use.Would it sound like
> a GPS navigation system?
>
> Moose
>
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