[photo-3d] Re: Better Viewers

[Abram Klooswyk <abram.klooswyk@xxxxxx>]

Michael Galazin 30 Mar 2001:
>(...) what would you get for focal length with three 
>achromats together? 

John A. Rupkalvis answered 31 Mar 2001 (and then got in a loop?):
>Anytime you add several elements together, you change the 
>overall configuration of the performance of an optical system 
>in more ways than just magnification ratios, often 
>introducing aberrations and distortions.  These have to be 
>corrected with - you guessed it - even more elements. 
>To keep from getting impractical, such designs require 
>careful calculation.

I fully agree with John. Using _three_ achromats to get the 
right focal length is asking for trouble, the usable image 
width as well as the distortion will disappoint you, 
I believe.

On the other hand, I spoke Hugo de Wijs yesterday at the Dutch 
club meeting, and he incidentally told me that he found out by 
accident that combining two achromats with the convex sides to 
each other gave the best image. He never has used much 
calculation, his magnificent viewers are made using just 
trial and error, and many years of experience of course.  

So you _can_ try to invent the wheel again...

Abram Klooswyk

 

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