Ken Durling schrieb:
>
> OK, not sure I can phrase this exactly right, but does anyone know
> how, when in Program mode, the camera makes its initial choice? True,
> I am tending towards aperture priority mode more of the time, and I
> know I can Program shift, but it would be interesting to know the
> "thinking" of the camera when in automatic mode. Does it choose the
> middle, or mean, of possible combinations for the given EV or what?
> (I am new owner of Elan 7).
>
It figures in the 1/focal length rule to avoid camera shake. Once there
is enough light for the resulting shutter speed at wide open, both,
shutter speed and aperture are equally used to further cut down the light.
There are example diagrams in the manuals of my cameras.
> Speaking of Program Shift, I sure wish they had put it on the Quick
> Control Dial rather than the Main Dial, or at least provided a C.Fn to
> switch. Holding the shutter halfway and turning the Main Dial at the
> same time is awkward at best. How is this on other EOS bodies? So
> far, this is the only thing I could call a "design flaw" on this
> otherwise delightful camera.
>
Yes, this is kind of a problem. OTOH, with a little practicing it's
quite easy to press the shutter release with the middle finger ...
> One more thing: being one of your "advanced amatuers" I am unclear on
> a point of DOF theory: I know that DOF is roughly 1/3 in front and
> 2/3 in back of the focal point (except in macro, where it is more like
> 1/2 and 1/2) but does this change significantly with f-stop? The
> weighting I mean, obviously DOF changes.
Oops. This 1/3 : 2/3 rule is a vaste simplification. The weighting
can change dramatically with the f/stop. The change is more pronounced
when you are approaching the hyperfocal distance (as focusing point)
at your set aperture. There is a nice section about this topic in the lens
FAQ, which can be found e.g. at the photo.net site.
Thomas Bantel
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