Anyone any idea what B 270 mirror substrate is?
Also, can anyone list out and cost what you would need to build this into a complete scope?
I think the b270 is super-heated silica (or sand) glass. It means it is almost "pure" glass, superlow expansion, and free of bubles and elemental impurities.
The cost of building a scope to suit? Depends on method of construction and materials, but if you were to go for a straight forward truss Dob, not much - say about four to five hundred yo-yos for the materials, minus the mirror cell and focuser bits. Thats using good 3/4 inch marine plywood and 2 X 1's.
