[photo-3d] Re: better viewers

[efbaskin@xxxxxxxxxxx]

Dr. George A. Themelis wrote:

> To get over this restriction, people have used two
> achromatic lenses per eyepiece.  If these lenses
> have the same focal length, then their combination
> has 1/2 the FL.  This way  you can pick two large
> lenses, say 30mm in dia. with 80mm FL each and
> by putting them next to each other you get one
> lens (eyepiece) with 30mm in dia. and 40mm in FL.

For the purposes of focusing and producing the best image, how should 
the lenses be placed in relation to each other and the slide? Should 
the lenses be placed as close to each other as possible? (Which is 
what I'm guessing.) Or should one lens be placed at the midpoint of 
the slide and the other lens?  And when focusing, should only one lens 
move, or should both remain fixed relative to each other?

Edwin


 

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