Thursday, August 7, 2014

Centering/Collimation Error

While reviewing the frames from the M8/M20 project, I noticed that all had a region in the upper left that was blurred.  The stars were streaked outwards and didn't look good at all.

So I ran CCDI on an example and this is what it shows:


When I did some measuring, it appears that there could be two things happening here:
Tilt and Centering.

Tilt makes sense because I've noticed the way that focus gets better when the camera shifts position.  I'd shimmed the camera body to avoid this whole issue.

Also, Centering makes sense, too, since I've had the focuser off the telescope several times.

So I put a collimation tool on the scope.  When using the Feathertouch-supplied 2 inch to 1.25 inch adapter, there was a slight deflection of the reflected laser.  I loosened the focuser and shifted it to show a centered dot.  What's annoying is that this centering wasn't uniform for the adapter - when rotated, the reflected dot wanders.

Tilt is easy to remedy.  I'll have to shim the camera adapter by wedging small bits of metal in the flange.

The final challenge will be to test and get some results from stars.