Re: [APML] Medium format wide field scopes

["Shekhar Borde" <shekhar@prodigy.net>]

> 
> > Is this true for just red (H-alpha) or is that true for the entire visible
> > spectrum?  Is the problem with an uncorrected scope that it can 
> > focus accurately within narrow passbands across the entire visual 
> > spectrum, but it cannot focus different wavelengths together? 
> > 
> > In other words, if I use a 400-410nm filter on this scope, will the star
> > sizes be as good as the ones using a 650-660nm filter?
> > 
> 
> The short answer is yes. The stars will be sharp. The long answer is that the 
> images will not register correctly because the focal length changes. This can 
> be overcome with software manipulation. Also, you will miss a lot of photons, 
> and you will be doing some very long and painful exposures to register any 
> kind of density.
> 
> Roland Christen
> 

Agreed.  But it sounds like it still has some potential for someone with 
limited funds (and lots of patience).  Unfortunately, patience would not
be one of my strong points :-/  

Thanks,

Shekhar



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