Re: Green Button Viewer

[P3D Dr. George A. Themelis <fj834@xxxxxxxxxxxxxxxxxxxxx>]

Steve Owsley writes:

>I just acquired a green button viewer.  I have noticed that in 
>comparing the image size to my red button viewer, in the green button 
>model the image appears slightly larger.
>
>Is this my imagination???

The lenses used in the two viewers are not identical but are very close in
specifications.  If there is a difference in focal length (= magnification)
it should be very small, too small to notice in viewing.  Due to the
construction of the case, the green button viewer keeps the eyes further
from the lenses than the red button and that might give the impression of 
increased magnification.

I have written a book on this viewer (see John Dennis' review in recent
Stereo World issue: "Three New Books from the King of Viewer Repair"! - the
cover of this book illustrates the article).  The book shows you how to 
take the viewer apart to clean and improve.  It comes with a new reflector 
and a pair of plastic nuts that hold the screws so they don't fall out
every time the top cover is opened (tip from Jon Golden, thanks Jon!)  

This is a nice viewer with glass achromatic lenses and capable of
dual DC (batteries) and AC (with rheostat) operation.  You can improve
brightness by re-painting (white/blue) the back of the slide holder and
replacing the old reflector.  I have bright 75V/6W bulbs for sale.  These
are much brighter (2 f-stops at every setting of the rheostat) than the
120V/10W bulbs.  One somewhat common problem is the interocular adjustement
that slips out of place.  Also, I have seen a few viewers with optical
misalignment which can be corrected by bending the metal piece that holds
the two lenses in place.  Another problem is that you cannot use the viewer
with batteries if you are missing the DC adapter (my book shows a clever
hookup that will let you do that using easy to find Radio Shack parts).
Other than that, this is an excellent viewer, top of the line for the
Realist, introduced in 1955 at a cost of $25 (vs. $20 for the red button).

Hope this info helps!

Regards -- King George ;)


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