Quote:
Originally Posted by raymo
Chris, Your 8" Newt was undermounted on an EQ5, need at least an HEQ5.
If your cameras wouldn't focus, you hadn't done your research, and had bought a Newt optimised for visual.[which is to say, most Newts].
You can't beat the laws of Physics, the 200mm has 5x the light gathering power of a 90mm. The secondary reduces light gathering by around 6%,
negligible. Your images may well be as bright, but will not show as much
nebulosity or colour, [for the same length sub],and on objects full of detail such as the moon will not show as fine a detail. Resolution is a function of
aperture, so the finest optics known to man will not allow a 90mm scope to
resolve detail as small as a 200mm will. Horses for courses.
raymo
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Can't argue with the laws of physics.......as long as colimation is always spot on. If its off your 200mm gathering capacity goes out the window because your image won't be great.
So unless you like to tinker....and tinker often with a cheap scope then maybe the refractor isabetter option. Was for me