"Ed Majden" wrote in message
...
Does anyone know where I can get a small sample/order for low
expansion
Invar metal? I want to try and make a 2-1/4 inch cut film holder for a
Celestron 8 inch Schmidt Camera. For folks familiar with the Celestron
Schmidt and their 35 mm single frame film holder I want to make a larger
version to accept 2-1/4 round disks of film cut from sheet film. This
will
give me a larger field of view, around 10 degrees. To control vignetting
at
the edge of the field the 8 inch will be stopped down to 6 inches.
Vehrenburg in Germany did this with holders he sold. Unfortunately I have
been unable to find one for sale at reasonable cost. Some seem to think
that these are now collectors items and worth a small fortune! :-(
Thanks:

Ed Majden B.C. - Fireball Network Coordinator - AMS Meteor Spectroscopy
West Coast Sandia Bolide Detection Station
Courtenay B.C. CANADA

http://members.shaw.ca/epmajden/index.htm

On Sat, 17 Sep 2005 09:07:55 -0300, "jtaylor"
wrote:


"Ed Majden" wrote in message
...
Does anyone know where I can get a small sample/order for low
expansion
Invar metal? I want to try and make a 2-1/4 inch cut film holder for a
Celestron 8 inch Schmidt Camera. For folks familiar with the Celestron
Schmidt and their 35 mm single frame film holder I want to make a larger
version to accept 2-1/4 round disks of film cut from sheet film. This
will
give me a larger field of view, around 10 degrees. To control vignetting
at
the edge of the field the 8 inch will be stopped down to 6 inches.
Vehrenburg in Germany did this with holders he sold. Unfortunately I have
been unable to find one for sale at reasonable cost. Some seem to think
that these are now collectors items and worth a small fortune! :-(
Thanks:

Ed Majden B.C. - Fireball Network Coordinator - AMS Meteor Spectroscopy
West Coast Sandia Bolide Detection Station
Courtenay B.C. CANADA

http://members.shaw.ca/epmajden/index.htm




Why not simply modify a roll film holder from a Graflex or similar??
Use 120/220 film, avoid having to futz around with a die cutter and it
will enlarge just fine..hard to develope that round disk, must be
between glass to enlarge.

Gunner, 4x5 lover

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner