Re: Viewer interocular

[P3D <PTWW@xxxxxxx>]

Many thanks to Greg Kane for the fine technical discussion of proper
viewer lens interocular spacing.  I will surely refer to it when I set
out to build an MF slide viewer in the not-too-distant future (I hope).

I don't think, however, that I can easily translate the technical details
into the steps that should be used to properly position the interocular
adjustment lever on a Red Button viewer.

Also, Greg's description suggests that when sharing a 50s slide viewer
with a group, the interocular should be set for each slide and left alone
as it is passed around.  Is that the intended use of the lever?  I had
always believed that each individual would need to adjust the lever to
accommodate their eye spacing (which, I have heard recently, would not
be necessary if the viewers were built with adequately large lenses).
(Note to DrT: this is not intended to incite a passioned defense of the
Realist engineers who designed the RB!)

Here is the method I have adopted for setting the lever:

I first close my right eye and position the viewer so that my left
(dominant) eye can see 100% of the left image (just barely possible with
eyeglasses on).  Then, with only the right eye open, I adjust the lever
so that I can see 100% of the right image.  For me, there is only one
point (the extreme close setting) at which I can see 100% of each image,
so there is no possibility of any slide-by-slide adjustment of the lever
without losing information from one image or the other.

Comments?

Paul Talbot


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