[Lvas] Telescope making,

[Gary Ahlers]

Hi Fred,

I'm designing a 10" Newt for Equitorial Mount so I am trying to keep weight to a minimum. 

Any experience with the Protostar Phenol resin Tubes? If they are rigid enough they look like a good alt. to aluminum - 40% less weight and already flocked.
I'm also looking at the Baader Turbo film to seal up the tube. It should help greately with the tube currents and will definately eliminate the mess from moth plagues like we had here several months ago.

For the mirror I think I will get an annealed glass with a 0.977 Strehl ration and 88% reflective coating and a 1/10 wave 98% coating 1.98" MA secondary. I found a neat little design program - NEWT 2.5. It has alot of whiskers but seems to work very nicely.

I use a Mallincam and SC1.5 webcam for imaging with an 8" newt now. At Prime focus both use a 1.5"  extension on on the low profile Crayford. Magnification gives me about 1/8 of the moon at a time. With a .5  FR I still can't get a full disc so I will need aspacer. Problem is I am hard up against the in stop with just the reducer. 
With the 10" I believe this will be even worse. Is shortening the FL by 1" enough? 

BTW, I have been using a Rigelsys N-Focus for electronic focusing and have found it a very good product and extremely reasonable. It works on pulse width and interval and runs a full voltage signal to the motor so it has never stalled or stuck even with 2 lb. plus payload. The low speed is easily field adjustable in both modulations and high speed requires pushing a second button. It uses a breaking circuit so there is no coasting. I have also tested it on a Jimi motor where it functioned flawlessly. It should work on most of the focus motors out there.

Any comments?

Thanks,
Gary A     
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