Re: viewers for real eyes

[P3D John Bercovitz <bercov@xxxxxxxxxxx>]

nearsighted jamie writes:
>     I would like have a slightly wider range of focus (specifically
> to have the lenses move closer to the film) as I am just shy of crisp
> focus without my glasses.

Well, the closer you rack that lens to the transparency, the more you
cut down your field of view.  Of course, you also get a huge gain in
the field of view just by moving your eyes up to the viewer's lenses.
Even a very mild negative trial lens between the viewer lens and the
transparency (but closer to the viewer lens) would retain your field of
view and allow you to use the viewer without your glasses.  The lower
the power of the lens, the less it can affect the goodness of the
viewing system.  Also, if the lens power is low enough, other eyes could
still use that viewer.

Astigmatic Chuck writes:
>  Is gear like that made so that it can correct for vision problems such
> as astigmatism?

Not that I know of.

>  CAN gear like that BE made so that it can correct for vision problems
> such as astigmatism?

I would think you could put two rotatable lenses with cylinder into a
geared mount that would drive them, like a differential, in opposite
directions to vary the power in cylinder and then rotate the whole mess
to align the cylinder with your astigmatism.  Seems like it wouldn't be
cheap except in quantity.  Better to just have your correction put in
some small lenses and put those lense near the viewer's lenses but on the
transparency side of the lenses.  Would only work for you, but what the
hey, right?

John B


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End of PHOTO-3D Digest 1473
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