Excuse me if I'm full of crap on this one, but I seem to recall that
DOF is relative depending on factors having to do with the circle of
confusion. I've always thought that's why it's harder to get selective
focus with Super-8 than with 16mm and easier still with 35mm. That's
one of the reasons people are so excited about Panavision coming out
with a full-frame digital camera because now DOF with 35mm
cinematography lenses will function properly. I'm sure some of our more
technical brethren will be able to illuminate this all more precisely
with trig equations and calculus functions that I won't be able to
follow, but I thought I'd chime in with my art-boy synopsis. ;-)
On Mar 27, 2005, at 10:10 AM, Walt Wayman wrote:
> Perhaps someone would explain to me why the DOF would be any different
> from what the scale on the lens indicates. It's still a 24mm lens,
> and just because it's on a digital whatzis that captures only the
> central portion of the projected image, making the FOV equivalent to a
> 48mm lens on a real -- excuse me -- on a film camera, shouldn't change
> the DOF. Should it? Would it? Does it?
>
> If I duct tape my 150/5.6 Schneider Symmar to the proper extension
> tube combination and attach it to an OM body, the DOF in the
> little-bitty bit I capture on 35mm film would be the same as the DOF
> in that same central portion on a 4x5 in. piece of film.
>
> Please show me the error in my thinking and give two examples.
>
> Walt, using an analog analogy
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