This is the first post concerning Amateur Telescope Making, which I plan to learn a lot about in the near future. I have done a lot of research and will undoubtedly do a whole lot more. A book was suggested to me by Ed Jones which has just arrived from Amazon. "How to make a telescope" by Jean Texereau, second edition. Ed was very helpful via email on a few initial questions I had. I have been looking into this art for a little while but I think the pinnacle moment was viewing the following video. When I initially saw it I had no idea who the teacher was, but I immediately knew I wanted to take a class from him. Unfortunately once I learned his name I knew exactly who he was and also that I would never ever meet this legend or attend one of his classes.
Math to determine Sagita (depth at center of mirror).
Depth = radius (half the diameter) of the mirror squared, divided by center of curvature (Twice the focal length) X 2
For a 10 inch mirror with a focal point goal of 8 feet (96 inches).
Radius = 5, squared = 25 / twice the focal length (96 X 2 = 192) X 2 = 384
25 / 384 = 0.06510416666666666666666666666667, or just plain .065 for short...
For another example:
For a 10 inch mirror with a focal point goal of 6 feet (72 inches).
Radius = 5, squared = 25 / twice the focal length (76 X 2 = 152) X 2 = 304
25 / 304 = 0.08223684210526315789473684210526, or just plain .082 for short...
Giving credit to a few other videos I have viewed and really learned a lot from:
Gordon Waite and series of his mirror making videos.
Sky At Night video, How to Grind A Mirror with Simon Lang and Terry Pearce.
Telescope Making [31c3] speaker Emmanouil "Madonius" Kampitakis
Grind a 6in and 10in mirrors by Carlos Paris.
Astronomy Podcasts episodes 327, 328 and 329 with Fraser Cain and Dr. Pamela Gay.