Re: [APML] Ideal Telescope (was M31 Mosaic project)

[Radu Corlan <rcorlan@pcnet.ro>]

> > Also, does a mak made with 'normal' glass (like bk7 or so) still perform
> > well below 400nm and in the NIR (down to 1u).
> 
> BK7 transmission is still 90% at 325nm and drops to about 3% at 290nm. It 
> transmits far beyond 1u in the infrared. What will limit the transmission is 
> not the corrector, but the coatings on the primary mirrors - this is the same 
> for both systems.

ok. But what about aberrations? Wouldn't the glass intoduce some chromatic
aberrations at the wavelength extremes (especially on a fast Mak (F9 or
so)

> > The reason i ask is because i'm thinking of a new scope, and i thought
> > that the only real option is the RC - but the fact that somebody 'in the
> > know' calls a mak his dream scope got me thinking.
> > 
> 
> The real option for a commercially made wide field telescope that can cover a 
> 6x7 film format is the RC. This does not mean that other designs cannot do 
> this as well. They are just not being produced. In fact, a well designed 
> classical Cassegrain can be made to cover a 2 inch format quite nicely with 
> pinpoint stars. One can even design and build a flat field Schmidt-Cass using 
> techniques similar to RCs and classical Cass (i.e. using aspheric elements 
> rather than all spherical design).

My particular interest is not in covering medium format, but a small-pixel
ccd; Something like an F7 with a diffraction limited, unvignetted field of
25mm or so. 

Radu

> 
> Roland Christen
> 


The future isn't what it used to be. 

-------------
Radu Corlan           Snail Mail: Bucuresti sect. 1, 
rcorlan@pcnet.ro             str. Argentina nr. 28, 71206 Romania

   You can still escape the "Gates" of Hell!   
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