You got it right. Use a bellows as a zoom.
Tom
--- Original Message ---
Date sent: Fri, 16 Jul 1999 16:46:26 -0500
From: Jay Maynard <jmaynard@xxxxxxxxx>
> On Fri, Jul 16, 1999 at 03:49:52PM -0400, Skip Williams wrote:
> > < Precision-made body caps, made from converted manufacturer's caps,
> > have a .259mm pinhole, approx. focal length of 50mm, approx. f/185 [...]
>
> Okkay, I give up. How does one control the focal length and/or aperture of
> a pinhole? What does varying the pinhole's size _do_ in that regard? For
> that matter, isn't the focal length of a pinhole the distance from the
> pinhole itself to the film plane? ...so while the focal length of the OM
> pinhole would be about 50mm (register distance of the lens mount plus
> thickness of the front part of the cap, roughly), the focal length of the
> M645 pinhole would be substantially longer because of the greater register
> distance? Am I missing something simple here?
------------------
From: Tom Trottier, President, ACT Productions Inc.
infoanim@xxxxxx http://www.act.ca
+1 613 594-4829 fax +1 613 594-8944
199 Holmwood Ave, Ottawa, Ontario, Canada K1S 2P3
"Make it as simple as possible, but no simpler" - Einstein
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