Re: [ATM] Lens after diagonal?

[Gary Fuchs <gary@rcn.com>]

Would that be the case even with a good quality lens?

Ken Hunter wrote:

>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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