--- Gregory Georges <[EMAIL PROTECTED]> wrote:
> > I have read before that the lenses on digital
> cameras, for
> > example, still exhibit the large depth of field
> that is typical
> > in wide angle lenses.
> >
>
> What technical reason is there behind the claim that
> digital cameras have
> large depth of fields?
He didn't say digital cameras have loarge depth of
field. He said that the DOF of lenses on digital
cameras is typically very great because of the very
short focal lengths involved. (Since the typical
digital camera has a tiny sensor, it also has a very
short focal length "normal" lens.) I'm not sure I
believe this, however.
>
> Will you have a larger depth of field with a digital
> camera using a 100mm
> lens, than a film camera using an equivalent lens?
No. or make that maybe <g>.
The thing that people tend to forget is that DOF is
directly related not to focal length as such, but to
image magnification. Sticking to 35mm for the moment,
we see telephoto lenses have narrow DOF. But that's a
product of large image magnification, not focal
length. Take a photo with a 400mm lens, and then the
same photo (from the same location) with a 50mm lens.
(Assume the same aperture for both). Now enlarge the
central part of the 50mm image so that prints from
each show the same magnification. Ignoring the
increase in film grain, you'll find both images show
the same DOF, because both have the same degree of
magnification.
So if you take a photo with, (as an example) a 10mm
lens on 1/3" sensor digicam, and a 70mm lens on a
35mm frame, and enlarge them both to the same final
image size, I don't see why the one from the digiam
would have more DOF. Anyone got a technical
explanation for this supposed effect?
I'm trying out a 3 MP digiam right now. I'll have to
test this out over the weekend.
=====
Bob Meyer
Life is uncertain. Eat dessert first.
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