Quote:
Originally Posted by AdamJL
This is me. Hence I bought a refractor :S
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And this is not a bad decision if you are unsure
One thing that helps to keep in mind with the tweaking of Newts is that by giving the Newt some TLC, you will be getting the very best out of the scope. You don't buy a scope to get a mediocre image/view, so the minutes it takes is entirely to your benefit.
But why does a Newt need such constant tweaking? 
(and the tweaking is only small touches)
The main reason is how Newts are built - essentially on a bunch of springs. This is to help keep the glass mirrors sitting passive in their cells. Over tightening the clips that hold the primary mirror in place, and this takes a surprisingly little amount of force, and it is enough to distort the delicate, finely ground reflective face! You might think that holding a mirror hard and fast in place is a good idea - no it isn't! If t he glass if warmed, it will expand, and if it is held hard and fast in place, it will be just like over tightening the retention clips, and the precious figures of the mirror is distorted - remember, we are talking about wavelengths of light. So the more the scope is moved about, set up & taken down, taken to a dark site, etc, these springs and screws will jostle and reset themselves as they seek to relieve the strain induced into them.
This is the trade off in getting larger aperture.
Even the giant scopes used in professional observatories need constant tweaking! These machines, despite the fine quality of the optics and machine, these are also susceptible to moving, and collimation needs tweaking!
And another thing to note about these professional scopes is while most do use lasers in the collimation process, the final verification of the collimation is ALWAYS done by star testing - the very same thing we do!
Alex.