Re: depth of field question

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From: Michael Healy (mjhealy@kcnet.com)
Date: 01/01/03-05:56:41 PM Z


Shannon, I have some anecdotal experience that may or may not be useful. I
experimented a lot w/ smallest aperture 8-10 years ago when I was using
35mm. The lens was a 24mm that I can shut down to f22. I could not see a
difference between f22 and f16 as far as resolution goes, and frankly I
don't think I was able to discern any problem w/ disfraction, either, which
I think may be the main bugaboo w/ the smallest aperatures. These were on
Kodachrome and 100 speed Ektachrome, several of which I got done as 4x5
internegs so I could make 11x14 c-prints.

Then in the late 1990s, I spent a lot of time doing found-light night work
in San Francisco's South of Market and China Basin areas, which are not
exactly known for a lot of even light. I was using Velvia and Reala in a
Fuji 6x9 that has a 65mm lens capable of stopping down to f32. Two things
about this: first of all, when you insist on using ASA 50 in dark alleys,
and have to resort to 10 minute exposures, and are working in summer temps
of 50 degrees, your +1 and +2 bracketing do NOT lead you to stand around
doing 60 minute exposures just so you have depth of field at f32. I never
did, anyhow. I would start at f16 if possible, and work my way down to f8
as necessary. I printed my c-prints as large as 16x20, and I never seemed to
lose resolution at middle f-stops. At the other end of the problem, I do
think that my Fuji reports degraded depth of field at f32 in relation to
f22. This is something I did start to notice in b&w enlargements. Again, I
assume that this is the effect of disfraction.

I now avoid that lens's smallest aperture. However, as I said, I have had NO
adverse effects from using f11 instead of f22. Not with this lens, not
focused for max depth of field. Probably it depends greatly on the lens and
also its focal length. And what you want to get in focus. The Fuji 65mm is a
pretty incredible lens, and is
very wide. Maybe other lenses would behave differently. Plus I suppose it
depends on your intended enlargement, as well as the process. With some
alt-processes, I can't imagine that you're going to notice it anyhow. I'm
using a pinhole on 4x5 now, and my print resolution is fine. Even a couple
negs digitally enlarged to 8x10 haven't looked bad on argyrotype. I suggest
that you experiment. Shoot the same images at a variety of f-stops, take
notes, see what comes out. You'll probably be relieved.

Mike

----- Original Message -----
From: "Shannon Stoney" <shannonstoney@earthlink.net>
To: <alt-photo-process-l@skyway.usask.ca>
Sent: Tuesday, December 31, 2002 3:18 PM
Subject: technique vs imagery; depth of field question; "tipped in"?

< snipped >

Speaking of technique, I have a technical question: today I was
photographing the broad side of a barn (literally) with an open doorway
(nobody was taking a leak in there at the time). I thought that since most
of the important stuff was between ten and fifteen feet away, that it would
be ok to use an aperture of less than my usual f64. It seemed like I read
somewhere that lenses work better at bigger apertures? That maybe there's
an "ideal" aperture for a lens, so that if you have a shallow depth of field
and no particular reason to want to make a long exposure, you might as well
open up the shutter to say f16. But I can't remember where I read that or
what the reason for it was. Did I dream that?

--shannon

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