Re: [ATM] Lens after diagonal?

[Ken Hunter <atm_ken_hunter@yahoo.com>]

Gary...

Yes, it will work but the lunch isn't free.

The thickness of the glass lens will absorb some of
the light and the fact that you are now a REFRACTIVE
system will introduce color fringes into the image
plane taking away the most desirable attribute of the
Newtonian design.

The small amount of difraction caused by the diagonal
mirror will bother you much less than the aberations
introduced by inserting a lens into the light path
even if you could mount the lens in such a way as to
reduce it's own difraction effects.

Ken Hunter




--- GARY FUCHS <gary@rcn.com> wrote:

> Hello,
> 
> I've been considering (from a perspective of almost
> no 
> knowledge) the problem of minimizing the secondary 
> obstruction in a standard Newtonian design. Could
> the 
> following work:
> 
> Place a lens immediately alongside a much smaller
> than usual 
> diagonal so that the cone of light, hitting the
> diagonal at 
> appproximately focus, would be refocused to a point 
> comfortably outside the tube.
> 
> If this wouldn't work - and I mean "work" in a
> practical, do-
> able, giving comparable results to the standard
> methods, way, 
> why not?
> 
> Thank you,
> 
> Gary Fuchs
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 



		
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