Olympus-OM
[Top] [All Lists]

Re: [OM] Crazy experiment

Subject: Re: [OM] Crazy experiment
From: "John A. Lind" <jlind@xxxxxxxxxxx>
Date: Sun, 04 Feb 2001 18:23:07 +0000
At 20:12 2/4/01, Frank van Lindert asked:
Jim, why the cable release?

Frank.

I'd be willing to guess that exposure will be measured in tens of seconds with an aperture in the high double-digits to low triple-digits.

It will depend on how he designs the pinhole (distance from the film plane) and speed of film used. Technically, a pinhole has no focal length, but the distance of the hole to the film plane (on axis) is often described as if it were one. There is an optimal diameter for a given hole-to-film distance . . . with several different philosophies about how "optimal" is defined. A hole too small suffers from diffraction limits. A flat film plane will have cos^4 falloff whereas a curved film plane will reduce the effect.

Extension tubes would be ideal for increasing the distance from the film plane. A separate pinhole with optimal diameter would have to be made for each combination of tubes though. Sorta like changing lenses again!

A body cap pinhole would give new meaning to the term "pancake lens." I have a couple old generics for the OM system that are about half the thickness of the Oly ones.

A good source for learning more about pinholes is here (the URL should _not_ be a big surprise):
  http://www.pinhole.com/

-- John


< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >


<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz