Re: [Utah-astronomy] Image scale basics (WAS: Ring Nebula (M57) - Be prepared to squint)

Joe, they are terrific telescopes, and have probably helped popularize the hobby more than any other. In fact I mis-spoke. I own TWO SCTs. I keep forgetting about the C5. Earlier this year I collimated it with a laser, and the imagery completely deteriorated. I haven't had the time or inclination since to dive into the problem and figure it out. And I have the C6 to use when I need the advantages of a SCT. BTW, many SCT imagers lock down their primary in the optimal position, and use an aftermarket Crayford focuser threaded on the back. There are many to choose from, and not expensive at all. I may try one, myself.