Quote:
Originally Posted by Wavytone
I've had a 12.5" f/3.7... It was an interesting experiment but I wouldn't recommend such fast mirrors to anyone aiming to use it as a Newtonian - only useful for a classical cassegrain. An f/12 20" Nasmyth would be quite a nice scope.
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It's not fast ratio that is the problem it 's the skill of the optician or lack of that give fast mirrors a bad reputation