Quote:
Originally Posted by casstony
The GSO 16" is f/4.5; do you think it would not be possible for them to make an f/4 with their current production techniques and standards, or would it simply take a lot more time to make each mirror?
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Theres a 25% increase in asphericity between F4.5 and F4 and the tolerance envelope is much tighter. I would rate the increase in difficulty at perhaps 50%. I doubt the 'masses' would pay the price difference to lose 8" on a eyepiece height. The premium mirror market allready has all that specialist stuff covered anyway. And F4.5 is probably the cut-off point at which you can `get away' with not needing a coma corrector, so there is some wisdom in stopping at f4.5 in the mass production market.