Thomas Bantel wrote:
> You seem to think about DOF a little different than I do.
Not necessarily. For my own work I think of it as a zone of apparent sharpness
extending in front of and behind the plane of true focus. The issue of what happens
to image sharpness when enlarged seems to me somewhat tangential, since then we're
talking about a lot of variables, including the resolution of the printing paper,
the sharpness (and focus) of the enlarger lens, viewing distance, etc.
But for the purposes of this discussion, which boils down to effective use of DEP
mode, a simple (or simplistic) notion of DOF suffices. The complaint was, in
essence, that DEP mode did not allow for a "Program Shift"-like change of
aperture/shutter speed values. Further discussion revealed that the person
originating the the thread was not always happy with the aperture--and therefore
the DOF--chosen by his 1v in DEP mode: he wants to be able to shift that value
from within DEP mode after the camera has made its exposure and plane-of-focus
choices. My response is that if he's not happy with the aperture/DOF chosen by the
camera, he's not selecting the proper points of focus for DEP 1 and DEP 2. These
two points function to define the front and rear limits of DOF (zone of apparent
sharpness), presumably while maintaining the highest possible shutter speed. Hence,
if the camera is choosing an aperture that provides a deeper DOF than the user
wishes, it is apparent that he has chosen inappropriate points for DEP 1 and DEP 2,
in terms of what he's trying to accomplish with a given photo. It seems to me that
it is less useful to complain about a lack of program shift in DEP mode than it
would be to practice choosing more appropriate DEP points.
> If I wanted to guesstimate (which is not too hard BTW and I
> do it most of the time anyway), I'd avoid DEP mode alltogether and use AV
> or M.
I agree; I mostly use Av mode.
fcc
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