The Duncan mask is a good starting point for defocused collimation especially if you don't know how far to defocus the telescope before starting the collimation process.
For best results always collimate with a focused star
Ok thnx for replies Ive collimated my C8 and 9.25 just using out of focus star with no probs but I spotted the Duncan mask on several other forums and thought an IIS member perspective would be good and perhaps a few people here might have been interested in the concept. Just found this, (http://www.iceinspace.com.au/index.p...63,187,0,0,1,0)
I see the Hartman is along the same lines. Im gonna make one anyway and try it, thnx..