T3D Re: custom lenses for viewers

[Bill Davis <bd3d@xxxxxxxxxxxxx>]

Very interesting discussion here.  I compiled the posts to date, waded
through them last night and now have a couple of comments/questions.

First a comment: My particular needs are for 5P Realist format only.  I'm
currently very satisfied with the image quality of my Kodaslide II.  I
don't notice the chromatic aberration others have mentioned and feel it
offers a sharp image free of curvature. 

A big drawback is the flat interlens panel. As I've mentioned before, this
bangs my nose and forehead, limiting my ability to even see the full 5-P.
Most of the good Realist-era viewers are set up like this, save that one
TDC model, but even that doesn't clear the schnozz. Thus lenses to retrofit
any of the Fifties viewers wouldn't interest me. A twin barrel setup ala
Radax or View-Master would suit me much better.

The other big drawback to the KII besides the flat interlens panel is
magnification, or lack thereof. If I were to spend lots of money for viewer
lenses, I would shoot for as close to ortho as possible, 35 mm (is that
7x?).  Certainly wouldn't go backwards in magnification, regardless of
image quality. Those 4x to 6x loupes just wouldn't work for me.    

John B and others have have hammered out a fine set of specs for all sorts
of performance characteristics, from flatness of field to distortion to
color weighting.   

My question is what are the performance characteristics of the lenses we
currently have?  I know the focal length of my Kodaslide but not how flat
or how distorted or how much chromatic aberration etc. 

Have any of the older viewer lenses ever been tested for these
characteristics?  Does anyone on this list have access to the test equipment? 

It would be very helpful to me to know those things when deciding whether
an improved lens is worth its cost. For that matter, maybe some of the
cheaper lenses like the Kodaslide I or View-Master could be tested too, for
a couple other points of reference.  

How *much* better is the KII than the KI and how *much* better is the
proposed design?

 Just wondering.


Best regards,
Bill Davis
mailto:bd3d@xxxxxxxxxxxxx



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