No, I think not. Blowing up equal-size areas of an image shot with the same
lens, no matter what format the image fell upon, should produce the same
results. It's the same degree of magnification, whether you're talking about a
12x18mm portion of a 35mm frame or the same size section of an 8x10 in. piece
of sheet film. Just because the lens is projecting the image onto a smaller
format doesn't cause an increase in resolution or contrast, nor does it reduce
the COC. Same lens=same image, same size, same resolution, same DOF, same COC,
same good or bad exposure, no matter what it's projected on.
Walt
--
"Anything more than 500 yards from
the car just isn't photogenic." --
Edward Weston
-------------- Original message ----------------------
From: "Piers Hemy" <piers@xxxxxxxx>
>
> That's true of the negatives, Walt, but don't forget that a half frame
> negative is enlarged twice as much as a full frame negar=tive ti get an
> 8x10. That extra enlargement "magnifies" the out-of-fcous areas on the
> final print.
>
> Thus the convention that DOF is related to format, specificaaly the size of
> the circle of confusion is related to the diagonal of the format. Smaller
> CoC gives smaller DoF, other things being equal.
>
> Don't imagine that I am a stickler for the conventional view of DoF - as it
> happens, I am not at all - but I do believe that the usable DoF from a given
> lens will be different if a smaaler portion of the frame ends up on a print
> of a given size.
>
> --
> Piers
>
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