Olympus-OM
[Top] [All Lists]

[OM] pinhole with OM-3

Subject: [OM] pinhole with OM-3
From: Peter Leyssens <Peter.Leyssens@xxxxxxxxx>
Date: Tue, 21 Apr 1998 11:51:43 +0200
I just wanted to elaborate a bit more on my self-made pinhole-body-cover
for OM-mount.  Kennedy reacted that I was crazy to waste a body cover on
it.  It has advantages : you can screw it on whenever you like and it's
more or less guaranteed to be light-sealed.  Also, this construction is
more sturdy than any cardboard construction.  You just screw on a lens
cover and it's pretty safe, even to put it in your pocket.

Exposure times are quite easy to calculate.  My 'lens' is f500.  Say,
f512.  This is exactly 10 stops away from f16.  10 stops = factor 1024,
say factor 1000.  So I take my 50mm/f1.8, I measure the light at f16 and
I get for example 1 second.  Multiply by 1000 and this is about 17
minutes.

Two remarks :
1) I can use my 50mm to measure the light because the pinhole is about
50mm away from the film plane.  *Very* handy, this one.
2) I know the Schwartschild reprocity failure, so I exposed my first
roll of HP5 with 3 times the exposure that I calculated.  This turned
out to be overexposed by, I estimate, 1 or 2 stops.  I think HP5 is
rather imune to reciprocity failure.  Now I'm exposing at exactly the
times I calculate and we'll see what we get.

So, pinhole photography is now compact, OM-compatible and it's easy to
calculate your exposure !  No reason not to do it anymore !

The only hard part in making the pinhole-body-cover is to get a hole
that is small enough.  I had my aluminum plate perforated by a
specialised tool maker with something like an electron canon (that
presumedly blows away the atoms !).  I didn't even pay for it, a friend
of mine blackmailed the guys :-)  *hm*.  Must be Belgium.

If I get around to scan some nicer pics, I could send them to the Oly
gallery.


--
Peter Leyssens
Eonic Systems

Support mail : support@xxxxxxxxx


< 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