on shallow DOF, Rob wrote:
> In any case I use a 50f1 lens regularly and yes it has a limited DOF,
> assuming a CoC of 0.033mm it provides about 25mm at its maximum
> aperture and minimum focus distance of 1m but hey I have more problems
> with my Pentax 50f1.2 at its minimum focus of 0.45m, DOF at f1.2 is a
> meagre 5.7mm.
Rob brings up the "other half" of the DOF phenomenon, here.
Most folks are familiar w/ the effect of aperture on DOF, as
it is easily seen and rather obvious. Many fail to realize
the significance of the focus distance in the overall scheme,
though. Basicly - as the focus distance diminishes, so does
the DOF - which is the base cause of such extremely thin fields
of focus in macro photography, even at tightest apertures.
Even wide open, a fast long telephoto focused at infinity or
thereabouts will have a quite wide field of focus. It is the
fascination w/ close focusing a long telephoto that results
in so many "thin field of focus/bokeh'ed background" images
which are seemingly the most desired type.
(I like these sort of shots as much as the next fellow, but
haven't really applied myself to taking many - my fastest
tele is the old 300mm f4, I could put a short tube on it to
bring it in close enough to go wild w/ the background if a
suitable subject would show itself, I suppose.)
Bill
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Bill D. Casselberry ; Photography on the Oregon Coast
http://www.orednet.org/~bcasselb
[EMAIL PROTECTED]
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