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Ray, my two mirrors are 7.5 inch. I am going to figure them to a sphere as they will be a long focal length (3000mm). The sagitta is only 0.7521mm according to my calcs (could be wrong) so not much glass to remove. I don't know how I'll go getting a good sphere as I've read that higher numbers are harder to interpret shadow wise but a ronchi may be the way to go. I think from my studies of the sphere it is a lot easier to get a smooth surface as introducing a parabolic figure can lead to zones and dog biscuit roughness. I want to keep this first Bino as simple as I can. Long focus telescopes are easier on eyepieces and eye relief for my old eyes and glasses.
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