There's a lot of info out there. I got suprised as it took me about 15 min. to find one of the sites that I've seen it at. That site is: http://www.idle.com/~markv/telescopes.shtml A number of the amateur astronomer types have put up pages that are full of all kinds of info. It's always wise to see what is out there as it may answer strange questions that you may have. I tend to make my answers on such subjects in ways that require you to do some work finding the thing. It's just the way I got taught by my father. He'd think and then tell me in a general fashion where to look for something rather than tell me what I wanted to know. As a result, I tend to act the same way to others and it sometimes causes problems. Interesting thing is that if the question is asked in just the right way then the answer just comes poping out rather than the direction to go - maybe I'm learning. Have Fun!