RE: ATM 3" f/6

[bj712@scn.org (Mark Zemanek)]

Krzysztof:

I know that Poland is known for some of its glass, and if you look 
around you, you might find some glass THICKER than 10mm that you can use 
for your mirror. Some suggestions...

*An ash tray...you know, the object used to catch cigarette ashes!

*Cut the thick bottom off one of those great beer steins!

*I bought a 4 inch, 19mm thick, furniture "glide" at a yard sale. 
This was originally used beneath the furnitures legs, to keep them from 
scratching the wood floors. 

You'll have to test the glass for stress with a polarizing filter, an
easy test to perform.

Personally, I suggest trying to find something in the 4" range. It'll be 
easier to work than a 3" (especially if you have large hands), and you'll 
be able to gather lots more light with it. You can also keep the mirror 
spherical (f/8 to f/10) and still have an easily transportable telescope.
Just my two cents worth...

Mark Zemanek
Seattle, Washington