For the same diameter, which instrument
to choose ? A Schmidt-Cassegrain, a refractor, a classical Newton or why
not a Maksutov ? In this article, you will find a way to compare performances
of all instruments destined to deep sky observing.
You never obtain sharp images and don't
know how to check your instrument collimation. Here are the detailed explanation
of optical checkings and adjustments (collimation) that you can apply to
your Newtonian, whatever its aperture.