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Hi Glend,
nice post below.
I think if you can get the central obstruction below about 18%
you would hardly notice the difference between a refractor & a Newt.
Then it boils down to how good your eyepieces are.
Some eyepieces have poor contrast because they scatter the light
either by poor choice of glass or bad coatings.
It's hard to get the central obstruction down to 18%
just by the design of the Newt. as the larger the Newt is
the bigger the secondary mirror must be to obtain all
of the light cone from the primary & reflect it to the eyepiece.
To do so you would have to get the eyepiece into focus with a low profile focuser
as close as possible to the telescope tube.
In that case the telescope would be only usable for eyepiece viewing &
no good for a camera which requires more back focus as it
works at prime focus.
Therefore - you need one Newt. for imaging & another one for viewing.
If you're rich you could have an exotic oil spaced refractor
with top eyepieces & do better than a Newt. on planets.
Oil spacing gives less scatter although with the latest technology & coatings this is debatable.
cheers
Allan
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