----- Original Message -----
From: "klaus" <klaus.ahlemeyer@netcologne.de>
To: <pinhole-discussion@spitbite.org>
Sent: Thursday, January 06, 2005 5:56 AM
Subject: [pinhole-discussion] "focal length" of SLR cameras
> Hello,
> I just plan to built a pinhole bodycap for my NIKON F3 and CANON AE1. Does
> somebody have experience in that and what is the distance form body cap
to
> film for computing the pinhole diameter?
The distance from film plane to lens flange is 44mm and 46.5 mm for Canon
and Nikon, respectively. That may or may not be the exact distance to the
rear of the body cap you will be using. What I would do is to drill a 1/4"
hole on the center of each body cap, then mount the cap on the camera, set
it to 30 seconds exposure, fire the shutter and insert a Q-Tip (remove some
of the cotton to make its tip less "springy" but leave some so it is still
soft, again, insert the Q-Tip until it touches the film plane and then make
a mark right at the front of the body cap, remove the Q-Tip, measure the
distance from the mark to the tip, subtract the thickness of the body cap
material. 30 seconds is way more than enough to do it, just make sure that
the Q-Tip is out of the camera by then or disaster will occur. I have done
it and it takes me just 3 or 4 seconds, so 30 secs is a safe and long time,
but just in case: you do it on your own risk!
Guillermo
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Received on Thu Jan 6 11:59:44 2005
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