[photo-3d] Re:transparencies vs. prints

[Alan Lewis <3-d@xxxxxxxx>]

Boris asks:

>In the viewer I own personally (a 1960s vintage scope), and I expect in
>most Holmes viewers, the prismatic optics create some slight chromatic
>aberration, and therewith a chromostereoptic effect that lifts fields or
>details with blue color and relatively depresses red features.  This is
>very irritating!
>Is this problem solved in the so-called achromatic lorgnette?

Yes, and it is corrected by just about any scope using high quality
achromatic lenses.
I have seen the blue/red lifting/depressing problem many times on my
stereocards. Viewing through achromatic lenses eliminates the problem.

>Of course it serves me right.  I should be shooting for and making images
>for the "classic" format in B+W, right, Bill?   The effect does not appear
>in B+W views, naturally, even though chromatic aberration may be apparent
>along contrasty edges.

I originally was inspired to use achromat lenses in my scopes due to
viewing black and white stereocards.  I was annoyed at the color
fringing, it almost ruined black and white images.
Achromatic lenses fix that problem too.

Another problem that you haven't noticed yet perhaps is that almost all
Holmes scopes place the lens height at well below the stereocard
centerline (vertically).  This introduces keystoning in the image. You
actually look up at an angle towards the stereocard! 
There are other minor problems with the typical Holmes viewer design
also.

The only scopes that are hand held/portable and correct for all this are
the Achromat Lorgnette II and the SaturnScope Achromatic Holmes viewer.

-- 
Alan Lewis  
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