Re: Re[2]: ATM 10in. Mirror

["John A. Volk" <103037.3107@compuserve.com>]

<NOT ON THE LIST

Hey just curious, have you ever compared that 10" with a commercial scope? 
(Meade etc.)

Also, did you say that the only testing you used was the star test for 
parabolizing? 


Thanks!
-tom>

Tom,

1) Definitely better than Meade/Orion class Newtonians and better figure than 
larger Galaxy mirrors I have tested.  I have not compared with equivalent size
Galaxy/Nova.  Not as good as a Cave 10"f/6 I used to have.  Much better image 
than 10" SCT.

2) Yes - this is the ultimate test.  Reading the errors can be tricky if 
multiple errors are present - however it is best to do general 
smoothing/polishing if this is the case anyways.  Turned edge, under and 
overcorrection are pretty easy to diagnose.  Watching the appearance of the 
secondary shadow in and out of focus also helped me a lot.  One important 
thing - the John Dobson method which I basically used gets you between a 
sphere and parabola when done polishing, making star testing interpretation 
easier.

Best Wishes,

John A. Volk