Re: V.M. interocular distance

[P3D Dr. George A. Themelis <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

telscope@xxxxxxxxxx (P3D Peter Abrahams) writes:

>It has seemed curious to me that Tyco markets Viewmasters to children, 
>when there are no children who can see both images in the few models I 
>have seen, with  adult-spaced oculars.

Dear Peter, this is a very good point.  As discussed in some length
recently, the VM system originated as a "grown-up" toy.  The spacing
of the lenses is based on the original design of the spacing of chips
in the reels based on adult requirements/measurements.  There is no 
interocular adjustment in VM viewers and such adjustment does not make 
much sense in viewing such small images through small lenses.  I believe 
that the lenses are spaced at the distance of the infinity separation 
of the VM images.

In retrospect, the choice of image spacing is very unfortunate since
is is much wider than most children's eyespacing.  None of my two
children (ages 8 and 5) can see 3d in a VM viewer due to limited
eyespacing.  My wife cannot see 3d in common VM viewers but she
can see 3d in model D which has larger lenses.

If VM was designed today, I am sure that it would have been designed
for smaller eyespacing, more appropriate for children.

Give that the infinity separation of the VM images cannot change
now, what is needed is a viewer with much larger lenses.  This
might work for the older children.

It's really unfortunate that VM's main target, children, cannot
see VM images in glorious 3d.  There is little that can be done
now.  Most parents, who pay the bill, can see VM 3d, that's
why the system still sells...

George


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