"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