The rule of thumb is that, on a flat film plane, the circle will be
3.5 times the focal length. So, if the focal length is 1" the circle
will be 3.5", if the focal length is 2" the circle will be 7", and so
on. The f-stop doesn't really matter for this rule of thumb.
----- Original Message -----
From: "Thom Mitchell" <tjmitch@ix.netcom.com>
To: <pinhole-discussion@pinhole.com>
Sent: Monday, March 25, 2002 5:44 PM
Subject: [pinhole-discussion] image circle relative to focal
length/fstop
How can I quickly determine the size of the image circle for a given
focal length and f/stop. I want to be able to keep an image circle
from getting too big, i.e. I want it to be 2' or 3''. Any quick help
would be appreciated as would simple rules of thumb as opposed to some
of the derivative calculus I sometimes see. Thanks for your help in
advance. Thom
Received on Mon Mar 25 22:08:31 2002
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