Re: ATM 6" f/4 or not?

[andydtg@alpha1.phoenix.net]

Tom Stock wrote:

>        The secondary would have to be a little over 2" for good 100" zone 
>     illumination, which then causes vignetting of the 75% zone at the 
>     eyepiece...
>        This seems like a big obstruction for a 6"...I was thinking it 
>     could make a good photographic scope however, except for the 
>     vignetting at the eyepiece....
>     Oh, and there are a couple of scratches as well...

My 2nd mirror was a 6"f5 (1st was f12) designed as an RFT. Used a 38mm
giant erfle and a 2 1/2" prism diagonal. 20x, 7.6mm exit pupil, and
a 4 deg field (70 deg apparent). Absolutely mind blowing views of the
Milky way, large star clusters, etc. Could be used w/o a mount sitting
in a chair or on the ground. It was easy to pack for camping & fun to use,
was sorry that I sold it later.

Andy Saulietis / DTG Alt-Az-Fp Drive Systems
12617 Harriet Ln
Santa Fe, TX 77510 USA
409-925-8854 Voice/Fax