[Jason D (Jason)]

Bird, thank you for the welcome

Eric, with respect to the secondary mirror concentricity and roundness appearance under the focuser, neither the autocollimator, the cheshire, nor the laser collimator are the proper tools to make this adjustment. It is the job of the sight-tube, Telecast, Teletube, or holographic laser collimator.

Bear in mind that the autocollimator, the cheshire, and the laser collimator use only a small portion of the secondary mirror – around the central area. None of these tools use or reference the secondary mirror edge. You could have a sequare-ish or triangle-ish secondary mirror and all these tools will work just fine.

About what you should see via the central pupil of the autocollimator when collimation is achieve is covered in post#3532765 in the following thread. I recommend reading the whole first page.

http://www.cloudynights.com/ubbthrea.../o/all/fpart/1

Basically, you should not see a hexagon but a single triangle. Left photo shows the wrong final image via the central pupil of an autocollimator. The right photo shows the correct final image.

Jason