Quote:
Originally Posted by barx1963
I'll probably get corrected on this but as I understand it being fast or slow is not really relevant for visual use. They are really photographic terms. A faster scope will produce an image quicker than a slower scope on a sensor or film.
As your eye doesn't work but accumulating signal it is not really relevant to what is seen.
Malcolm
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It is a bit relevant in that you get a more contrasty view through a slower scope, so the sky will look blacker through an F15 scope than it will through an F4, but most people care about if for imaging. For instance Hyperstar turns your F10 cope into an F1.9 light bucket, which makes a huge difference to exposure times.