Re: ATM Re: ATM Cassegrainian coudé: weird image at focal plane

[Bernard Maugoust <maugoust@free.fr>]

In message <5.1.0.14.0.20030527165020.00ae18a0@popd.ix.netcom.com>, 
 Michael Peck <mpeck1@ix.netcom.com> wrote:

> I think baffling for a cassegrain with a Nasmyth flat should be the same as 
> for an ordinary straight-through cassegrain, except of course that you have 
> to provide a hole in the side of the primary baffle for the light from the 
> tertiary to get through. I've shown how to calculate baffle dimensions for 
> a conventional cassegrain using simple algebra. Just follow the links.

Thanks Michael. I'll soon see if my simple common sense was up to your simple
algebra ;-)
 
> As for the problems finding an image you described earlier -- the math > doesn't lie. If you've worked out the design correctly and the component 
> parameters match the design within reasonable tolerances you will get a 
> real image where you expect it to be. If you can't find it and you're 
> confident no parameter was mismeasured then it's most likely that the image 
> is just being swamped by stray light.

I really hope it would be just that. If it's not, I'll have to sketch what I
see as good as I can, and make it available to some experts among you.

> I don't think the problems you  described could be due to poor optical
> quality in any of the components.
> 
> Reassembling the telescope with at least partial baffling and testing it at 
> night on some bright & easy to find object seems like a reasonable plan

It's tomorrow's job to be with 2 acceptable baffles at the end of the day.
BTW, would Mars be a suitable target early in the morning?

Cheers,

Bernard

-- 
Bernard Maugoust 3°59'E 44°28'N