DIY Friday: Tuning Your Newtonian Reflector
The tuning of a telescope is actually called "collimation," and Sky and Telescope shows you how:
To get your telescope well collimated, here is what you need to accomplish:
Step 1: Center the secondary mirror on the axis of the focuser drawtube.
Step 2: Aim the eyepiece at the center of the primary mirror.
Step 3: Center your primary mirror’s sweet spot in the eyepiece’s field of view.
In most cases, only the last of these three steps will need to be repeated regularly; the first two are more or less set-and-forget operations. Now let’s get to the nuts and bolts of actually collimating your reflector
It’s a rather simple telescope and could build one yourself for about $150.
