: Ian, : Anything less than 3" at a minimum would be generally ineffective : for very much. Since you're in a light polluted area, even that can : be very small. Portable instruments have been made to some amazing : sizes. Consider an Astroscan (5" I think) for a start. It is a very : short FL unit that can be handheld for quick views and is quite sturdy : and can be pretty much banged about a bit. There have been Cass. scopes : that set up in seconds and can be carried in a big fannypack type of : case. One fo the famous Amateurs (can't remember his name at the moment) : made one many years ago which was a pretty naked set of optics and support : for the secondary. If anything, if I was going to make a superportable : instrument, the Cass. design allows for pointing and looking at the same : direction. The only problem with that design is that anything less than : about F8 gets to be rather hard to make and keep aligned well. My best : suggestion is to find a small dob type scope that your prof's will allow : in the area of the work enviroment. Stargazer Steve just came out with : a 6" which is on a tripod and is probably very good for your uses. You : might also consider some 15x20 or up to 20x80 binocs. That's my ideas on : the subject. : Have Fun and Keep Looking Up! Bob May

Ian and Bob. Hello, I'm pretty sure the famous A.T.M you mention is Horace Dall. Without name dropping, a very old friend of mine who died many years ago. He built a number of telescopes up to 15" using a very simple arrangement of rods or folding members which would support the optics. He was probably the most emminent English amateur and part inventor of the so called ' Dall-Kirkham ' optical system. There are several references to his telescopes in the S & T magazine. Let me know if you want more information. Best wishes, David. (England)

• Re: Very small mirrors - bobmay - September 15, 1998 - 21:34 UTC
  • Re: Very small mirrors - Jose_Henrique_Schreiner/">Jose Henrique Schreiner - September 26, 1998 - 20:34 UTC