You're actually saying if one zoom out (reduce the magnification of the
subject) and crop back to the desired composition the DOF will be
increased, right? So the pic taken with the zoom at 35mm will present
greater DOF than the one taken at 70mm, after you enlarge both to the
same subject size, right?
...so the K20d has greater DOF than the *ist DS, right?
I love numbers... :-)
LF
JC OConnell escreveu:
depth of field is determined solely by in camera magnification
and working fstop. So cropping/format is not a factor but changing
lenses from a given distance will affect DOF, likewise moving further
away with the same lens and stopping down more will also both increase
DOF.
JC O'Connell
[email protected]
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Larry Colen
Sent: Monday, April 06, 2009 4:35 PM
To: Pentax-Discuss Mail List
Subject: Trading resolution for depth of field
Perhaps someone has already done the math, or the experimentation, and
can just give me the answers.
Scott's pictures of his Nishiki inspired me to shoot some of my mongrel
legnano. I rode it to lunch today, and on the way back to the office was
getting some shots of it with some lupin by the side of the trail.
I didn't have quite as much depth of field as I'd like, so I decided to
try zooming way out and then just cropping. Smaller sensor, shorter
lens, more depth of field. If the equation is linear, I should get the
same DOF by downresing (downrezzing?) a longer lens over the whole
sensor, as I would using a shorter lens and cropping.
This would also mean that a K20 would have a lot less DOF than my K100
at the same focal length, assuming that they were blown up large enough
that the sensor resolution became a factor.
So, if I'm willing to trade resolution for depth of field, am I better
off using a wider angle lens and cropping (my intuition says yes), or do
I get the same benefit by just combining pixels (which would also reduce
noise) for a larger circle of confusion?
--
Luiz Felipe
luiz.felipe at techmit.com.br
http://techmit.com.br/luizfelipe/
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