Re: [photo-3d] viewer optics

[Brian Reynolds <reynolds@xxxxxxxxx>]

George Themelis wrote:
> 
> My question is, why didn't any other design make it to a
> stereo viewer?  There must be a reason for this.  What is it?
> 

Without asking someone directly involved with the design and
production of the viewers in question I don't think we'll ever really
know.

Being somewhat cynical I think that since these were intended to be
mass market items the cheapest design that the public would actually
buy was chosen.

Today many viewers (e.g., various MF viewer designs) use cemented
doublets because they can be found easily and purchased in small
quantities at reasonable prices (often through surplus dealers).  A
55mm Tele Vue Plossl in a 2 inch barrel goes for $228 (each) and would
be a bit expensive for a slide viewer (regardless of whether or not it
could actually view the whole slide).  Greg Erker has done some work
with using pairs of surplus cemented doublets in home made viewers.
See <URL:http://www.angelfire.com/ca/erker/> for a couple of examples.

> - Double element, glass, airspaced (Some Busch and Sterling, Airequipt, 
>    View-Master model D).  This is not an achromat.  It offers larger
>    size and better magnification and some eye relief but suffers
>    from noticeable aberrations, like chromatic aberration.  It also
>    needs regular maintenance because of the humidity settling
>    between the two elements.
> 

Air spaced doublets can be achromats, but apparently the ones you
mention are not.  They were obviously designing for different
qualities (magnification, etc.).

> Why only the Kodaslide II has coated lenses (unfortunately, inferior
> to other "achromats")?
> 

By the 1950's Kodak was coating all of its lenses.

> Sounds like this is the design I call "double achromats" used 
> in the contemporary European viewers. I don't think any 
> manufacturer or importer/seller has called them "plossls" 
> (but maybe I have missed it).
> 

Within the astronomy community they are called Plossls.  They are
related to Kellners (and Edmund's RKE).

> If anyone is interested in getting one after Brian's "endorsement", 
> please contact me off the list and I will get you one!
> 

Brian "endorsed" a particular green button viewer he was in NYC.  I
don't know if I'd like any other green button.  I haven't particularly
liked any of the red button viewers I've viewed with, but I admit to
using a limited selection of red buttons.

-- 
Brian Reynolds                  | "Dee Dee!  Don't touch that button!"
reynolds@xxxxxxxxx              | "Oooh!"
http://www.panix.com/~reynolds  |    -- Dexter and Dee Dee
NAR# 54438                      |       "Dexter's Laboratory"

 

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