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'Slow' dobsonian+ reducer for a good all-rounder for beginner ?


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Hi guys. Is this a smart idea if one wants to have a dobsonian for both DSO and planets, especially for a beginner  ? For example, the f/7.85 150P Skywatcher dobsonian with a 0.7 reducer will give me  f/5.5.  Will it show less coma (with the reducer) compared with a native f/5.5 dobsonian lets say ? Or  I'm chasing the wind here..lol

 

The truth is that I'm pretty much a beginner at observing but I like reading up tons of stuff about equipment before buying.  I'm currently using or a pair of Oberwerk 15x70 binoculars  on a tripod, and I'm  thinking about a dobsonian...And a 'slow' dobsonian used with or without reducer looks like a good all-rounder, for planets and DSO

So, good idea ? Or is this a case of ' jack of all trades, but master on none'..lol

Any help and further reading suggestions will be muvh appreciated. Thanks

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You don't need a reducer to change the focal ratio for visual astronomy, you instead change eyepieces to alter the exit pupil size and/or field of view depending on what object you are looking at. A "standard" 1200mm 6/8/10" dob is a good all round telescope choice and a good alternative instrument to your binoculars. I have both 16x70 binoculars and an 8" dob and think it is a good pairing. 

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Adding a focal reducer to a Newtonian will probably just exacerbate the inherent coma of the desig, add field curvature, add other edge aberrations, and reduce back focus to such a point it may not be possible to bring most eyepieces to focus.

If you really want a fast Newt for wide field views, go with an f/3.9 astrograph with a TV Paracorr T2 instead.  The large central obstruction will limit its contrast for planets, though.

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