Re: [ATM] Elliptical mirror

["Malcolm Macdonald" <toliman@wave.co.nz>]

Sorry Jeffrey,   I overlooked the obvious confusion that could result from
my term 'elliptical secondary. I should have known better.

What I am making is a round, concave, 4cm.  f 2.8 lens, for a Gregorian type
telescope. It is to have an elliptical figure and my problem is to produce
an ellipse rather than a parabola.

thanks for your prompt reply.

Malcolm


----- Original Message ----- 
From: <jroweapp@postoffice.swbell.net>
To: "Malcolm Macdonald" <toliman@wave.co.nz>
Sent: Tuesday, March 23, 2004 3:51 PM
Subject: Re: [ATM] Elliptical mirror


> Dear Malcomb;
> I imagine what you want is a flat mirror shaped as an ellipse, ie. a
> really flat oval. Forgive me if I presume wrong.

>
> Malcolm Macdonald wrote:
>
> >I need some help with figuring an elliptical secondary for a Gregorian
> >telescope ( well two actually). There is plenty of  information available
> >about  the ellipse, but it all concerns how it can be avoided or
eliminated
> >and little about how to create one.
> >
> >My first question is:  How do I set 'Fig XP' for an ellipse.  I presume I
> >must alter the desired deformation number. What is the magic number that
I
> >alter it to?
> >
> >Second question:  Is there any special stroke that will produce an
ellipse.
> >I have pressed  paper stars into the centre and outside edge of the lap.
Is
> >that the correct thing to do?
> >
> >Any other tips or advice from an experienced person would be appreciated.
> >
> >Thanks
> >
> >Malcolm
 >
>


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.624 / Virus Database: 401 - Release Date: 15/03/2004

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