New to everything. Trying to collimate my XT10 (no specific forum for Orion?) and having trouble with the 1st adjustment: centering the secondary mirror in the focus tube. It needs to be moved to the right. Turning the adjustment screw of the base of the mirror counterclockwise makes it move to the left, moving it right begins moving it to the right but then it starts moving to the left???
Any experience or help here?
First, "It needs to be moved to the right" is a little difficult to understand. The secondary mirror has three adjustments--tilt, rotation, and position closer to or farther from the primary mirror. When you're trying to "center the secondary mirror in the focus tube", you should be looking for three circles:
the bottom edge of the focus tube, (light blue circle)
the actual edge of the secondary mirror, (green circle) and
the reflected edge of the primary mirror. (red circle)
You want to make these three circles concentric.
I've attached an annotated image to help. Note that, when you get your scope collimated, all of the circles (and the primary mirror center marker/donut) will be concentric, except the silhouette reflection of the secondary mirror (violet circle) which will appear offset toward the primary mirror end of the tube assembly. And don't worry about offset--if you make the three circles concentric, the silhouette reflection will automatically be offset.
It will also help if you use a tool to keep your eye centered. If you don't have a collimation cap, you can get one like this: https://agenaastro.c...t-eyepiece.html
And it will also help you see the actual edge of the secondary mirror if you place a piece of white copier paper behind the secondary mirror against the inside of the tube wall (opposite the focuser). Do NOT cover the primary mirror!
Edited by Vic Menard, 28 September 2021 - 02:28 PM.