The way I read your post is that you want to align the secondary and primary BEFORE optical collimation?

I used to own a 8" SVD and collimated it many times. By leaving the primary alone for now and adjusting the secondary mirror isn't that hard. What most folks don't realize is that there is an offset on the secondary. This offset is slight and by correctly adjusting the secondary, you will "off-handedly" do an offset. Personally, I find it difficult to really explain mechanical and optical collimation without proper visual aids in understanding the method of collimating.

The 8" SVD is at f/4 and collimation is slightly more critical. Though some people may disagree with that statement, however my experience says otherwise through trial and error over the years.

Down below is Mel Bartels Collimation website that explains mechanical/optical collimation and explains offset. Give that a try and good luck!!

http://zebu.uoregon.edu/~mbartels/collimate/collimat.html

• Orion Skyview 8 - burgman - March 15, 2002 - 21:36 UTC