Re: ATM A Hearty Thanks to Peter Smith!

["Kam Marine" <nutsp@alltel.net>]

I want to second that!
Thanks Peter and all you other atmers around the world who help people turn
dreams into reality by sharing your knowledge with others.
I learned almost everything I know about making telescopes, from your many
informative web pages .
Have a great week!
Stan

From: "Roger Ceragioli" <rogerc@as.arizona.edu>
| Thank you so much, Peter, for your excellent web material concerning
| Ronchi matters!  This is of great value!
|
| What I have seen in my own recent testing is very much in accord with
| your photos and simulations.  And if one will look even at Mike
| Spooner's excellent 8" f/5 mirror (tested in autocollimation) and really
| scrutinize the Ronchi bands, you can see small (presumably) diffraction
| effects at the edges, even though he was using a 100 ln/in. grating.  A
| 200 ln/in grating would have showed them even better.  Knowing Mike
| personally, as I do, I absolutely trust his judgement concerning the
| quality of his mirrors.
|
| But I don't automatically know which Ronchi band deformations in WHAT
| MAGNITUDE are acceptable.  And that has been my problem all along.
|
| So many thanks also for simulations of what turned edges should do to
| the shape of the bands.  These simulations are even more helpful.  In
| fact, if one could compile a kind of illustrated manual of what Ronchi
| bands should look like for both spherical and parabolic mirrors, with
| and without various aberrations and zones, that would be exceedingly
| useful for ATMs and professionals too!  Malacara's chart just doesn't
| show enough possibilities.  I know that's a lot to ask, but dummies like
| me who can barely use a computer, much less download, extract and learn
| new programs would be highly grateful for this assistance.
|
| Best regards,
| Roger Ceragioli
|
|
|