From: Christina Z. Anderson (zphoto@montana.net)
Date: 12/17/02-10:59:41 PM Z
<Sam Wang said>
> At long focal length, a pinhole certainly CAN give you the same
> Giacomelli-like flattening effect. I wonder whether you can obtain as
> good sharpness as wide angle pinhole images though. Try it and let us
> know.
Absolutely you can. At any focal length you have your optimal pinhole size
to create optimal sharpness. On one side of optimal sharpness is too fuzzy,
on the other size is too sharp leaning towards diffraction which then makes
the image...foggy...is the best term to use. Degraded. Right around
optimal aperture you have a leeway of a number of different pinhole sizes
that you can use, a range so to speak. I have had pinholes that are too
sharp so that they look like just plain old Kodak point and shoot shots.
Along the same line, I have had pinhole cameras that have too "normal"
a focal length, so that they, too, look like point and shoot images even in
4x5. I would always try to exploit the benefits of pinhole which are size
distortion, universal focus, rectilinear non-distortion.
> By the way, it is critical that the camera does not move during the
> long exposure. Not even a little bit. Which may not be that easy with
> the bellows completely extended and the exposure going to be so long.
> Remember all the talk about reciprocity failure? Let's see, f/750 is
> about 12 stops from f/16, so going by "sunny 16" rule, it's 8 seconds
> in bright sun with ASA 400 film, before reciprocity correction.
Well, when you have movement at long exposures, you get what I term
"acceptable" blur, which is effective, works, is not irritating to the eye,
unlike motion blur with a normal camera where the double image, both sharp,
makes the eye feel sicky. Oh my gosh, could I be any more scientific in my
descriptions or what???? But you know what I am saying, I am sure.
Chris
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