Re: Interocular&focus necessary?

[P3D Gregory J. Wageman <gjw@xxxxxxxxxx>]

Dan Keen inquires:

>Have a question about how necessary are features like focus and interocular
>adjustments are on stereo slide viewers?

To supplement John B's expert opinion, I have used both Realist, Revere
and Delta Stereo viewers with focus & interocular; also various True-Vue
viewers and those ever-popular "$3" Realist viewers, which have neither.

One advantage to a focus mechanism is IF you wear glasses (you said you
did) AND the focus rack has sufficient travel AND your eyes don't differ
much in the amount of correction required, you MAY be able to use a
focusing viewer without glasses (enough conditionals for you?).  I can
do so with a Realist, but the Revere doesn't quite have enough inward
travel (I'm near-sighted).  The advantage to this is you can get your eyes
closer to the lenses and thus get a wider field of view.  With 5p
images, this isn't so important as with wider formats; with 8p full-
frame it is almost essential, if you want to see the while slide at once.

My understanding is that all these viewers put the slide at the focal
distance from the lens, effectively putting the image "at infinity".
Since you're far-sighted, you may not need your glasses even if the
viewer lacks a focus adjustment.

	-Greg W.


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