P3D Re: lens pairing

[George Themelis <gthemelis@xxxxxxxxx>]

> I was also wondering what are the best ways to pair the lenses
> for 3D.  Some earlier posts were suggesting just to compare
> the size of the image projected on the wall through the 
> lenses.  Is it enough to test just that?

Yes.  Or you can make prints and measure the size of a given
object in either print.  Or you can just mount the slides in a
good mount, align the bottom and check the top.  If the images
are of different sizes then it will be obvious to the eye.  If
you use RBT mounts you can take advantage of the unique vertical
alignment method and dermine the deviation in 0.1mm increments. 
The total height is about 23mm.  So 0.1mm deviation corresponds
to 0.43% or roughly half a percent.

> What was done to find good pairs, for example for Realist 
> camera, when it was manufactured? 

I would imagine that they tested the lenses in an optical bench
and tried to match focal lengths.  The Kodaslide II viewers have
numbers penciled in each eyepiece, small integers, positive or
negative.  I imagine this is the deviation from a standard FL
and lenses were matched to be within a certain range of
deviation.

George Themelis

=====
George Themelis, DrT-3d@xxxxxxx
http://home.att.net/~drt-3d/
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