I know how to collimated this telescope roughly using the defocused image of a star , however I'm thinking of using the telescope for planetary imaging and want to collimated it more precisely. For this I need to examine the airy disks around a focussed star at high magnification. However the atmosphere is rarely still enough to make these observations and I'm considering making an artificial star to do the job. On reading comments on the net about collimating a SCT I find that many have the opinion that if a SCT is pointed horizontally the primary mirror moves forward making accurate collimation impossible and that it must be pointed up at 20-30 degrees to overcome this problem making use of an artificial star very difficult. Would appreciate any comments.
Regards philip
