ATM star test of 6"er

[JoAnn Nanof <jnanof@javanet.com>]

I finally had the chance to star test the 6" f6 unaluminized mirror I
made. I had a very dark (limiting mag 4.5 for the city is the best it
gets)night and the air was above average steady. I masked off the outer
6mm for slight tde. I made my 2nd thin wire spider and I am hooked, no
spikes whatsoever! Still have a vibration problem though.

First took a peek at the moon. At 190X using 4.8 Nagler the image was
sharp as a tack and good contrast. Using a 2x barlow for 380X the image
only degraded slightly in sharpness and the contrast was reasonable. 

I did the star test on vega. At about 100X (16X/in) I saw no difference
in the inside and outside of focus as far as the diffraction rings were
concerned. The rings were sharp and easily defined inside focus but
there was a small difference in the sharpness outside focus. I think
there may be a bit of a raised ring before the tde. At 190X (31x/in) I
had the same results. It was a bit more difficult to judge at this power
due to outside influences ie tube currents, vibrations and lots of eye
defects. Nonetheless the point of focus was clear and obvious at this
power, something I do not have on my 8"er. 

I tried to test without the mask but I was so far off collimation that
fustration got the best of me. I will test again tonight. Thank you to
the entire list for helping me make a great mirror! Next up a 16"?
-- 
Searching for Parabola,
JoAnn.
Portland, Me.
Adventures of ATM Woman!
http://members.tripod.com/nanof/atmwoman.htm