The Film Holders

This shows the components of the film holders, on the left is the platen which has a convex curve machined

on it which has a radius of 22.25" the same as the fl of the mirror. The top shows the front side of the holder

with a focus grid. These are threaded for 48mm filters which I use, Ha from Lumicon , RGB from Schuler.

On the right is a machined cap to cover the holder. Not pictured I also use the Celestron roll film adapter

which works quite well on the unfiltered exposures. The filtered shots are on TP2415 which I process. I

use chips on the TP shots because of scratch problems with the roll holder. The lower shot is of the

backside of the holder showing the alignment holes and the film tension bolt. All aluminum parts were

anodized black by Chem-Research of Phoenix.