Re: [ATM] LWT setup questions

["john sherman" <atm@mail.johnspics.com>]

>"Someone" is  Peter John Smith who not only desceibed it 
>but invented it as well. 
>http://www.users.bigpond.com/PJIFL/page40.html 

Hi Vladimir, 

Thank you!


Hi Bernard, 

>(even though the maths page goes way over my head). 

Mine too! 

If I was making a mirror right now, I would do it this way. Use the Foucault test to keep getting towards a sphere, itz just a knife and a light. Periodically I'd use the spot test to make sure there is not enuf primary astigmatism to see. Itz just a spot of paint on a glass slide, and a pinhole light. I would use the LWT to figure with. Of course I'd finish up with a star test. 

On my old 22" I had a hard time with the Couder mask, judging those funny shadows. A cheapie LWT tester gave me reasonably repeatable results, it is the only method I know which would give me the confidence to figure with (James Burrows' new 2D Hartmann test looks pretty good. I've been wanting to try it out, and see how much confidence it gives me). Long ago I tried figuring an 8" with the Couder test and got nowhere. If it was the only thing available, I would never make a mirror.

What part of the spot test gave you a problem? 

Have fun,

John 






_______________________________________________
ATM mailing list http://www.atmlist.net/