[Dennis]

Hello,

Here are some photos of the Baader Solar Film Astrophotography Solar Filter that I have just completed. The design is made up of an OTA mounting ring and a Baader film retaining ring as follows:

OTA mounting ring:
9mm plywood ring; OD=11.5ins, ID=10.5ins.
6mm plywood ring; OD=11.5ins, ID=10.5ins.

These were glued and screwed together to form a 15mm deep ring that fits over the corrector plate cell on the C9.25 OTA.

Baader film retaining ring:
4mm plywood ring; OD=11.5ins, ID=9.25ins (top ring)
4mm plywood ring; OD=11.5ins, ID=9.25ins (bottom ring)

The bottom ring is glued to the assembled 15mm OTA ring. Then, the Baader solar film was then placed on the bottom ring whilst the top ring was then screwed down in 6 places.

On the inside of the OTA mounting ring, I cut x 3 shallow recesses at 120 deg spacing in which I glued thin foam strips to snugly secure the filter on the OTA. I also drilled and tapped x 3 holes for nylon locking bolts so that once fitted, the filter can be firmly locked in place.

Cheers

Dennis