From: "Tom Krajci" 
To: 
Reply-To: "Tom Krajci" 


>From: "Mel Bartels" 

>Sorry I didn't make myself clear.  It is not a question of 'will it
work'
>because Tom Krajci uses this 6 pt cell in his thin mirror 16 inch and
his
>scope performs optically wonderfully.  Not a hint through the eyepiece
at
>highest powers of anything other than a very nice star test.  He's had
this
>scope running for several years now.  I am sure he would invite you to
look
>through it but he is in Uzbekistan (I think that's the correct country)
>right now enjoying some very dark high altitude skies. When he
returns...

My mirror is pyrex, 16 inch diameter, 1.6 inches thick.  It is RTV glued to
a six point cell.

According to PLOP I get an RMS of 2.35e-06 and P-V 1.5e-05 millimeters. (Refocus ON.)

I also have a ten inch, 1.3 inches thick, pyrex, on a four point support. 
It also shows no sign of image spoiled by the mirror support. According to
PLOP I get an RMS of 1.6e-06 and P-V 9.4e-06 millimeters. (Refocus ON.)

Based on several years of use of both mirrors, star testing, etc....it
seems that if PLOP gives you RMS of about 2e-6 or better...your mirror cell
should be 'good enough' in all but the most ideal of observing conditions. 
(Assuming you build and use the cell properly.)

I hope this helps.

...and I'll be back from Uzbekistan in about a year.  Where will I be
stationed next?  Only God and the Chief of Staff of the Air Force know for
sure!  ;-)

Tom Krajci
Tashkent, Uzbekistan


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