Re: Dual Camera convergence points

[bercov@xxxxxxxxxxx (John Bercovitz)]

Glenn Stokes writes:

> *  Seeking suggestions and input on ways to create realist and VM chips 
> from full frame.

Personally I'd just mount the slides in 7-perf mounts instead of Realist 
mounts and be done with it.  For the VM stuff, I would talk to Bob Mannle.  
He does that sort of thing for a living.  You just give him the 
transparencies and Bob's your uncle.  8-)

> * Since the full frames were not created in a strictly parallel alignment, 
> is this going to cause some grave problem.

Nah.  Space will be warped but that's not a problem unless it's a known 
geometric object like a box or a pipe or something like that there.

> * Where can I obtain lenses so I can experiment with creating my own 
> 2x2 viewer. I am extremely nearsighted and would like to create a viewer 
> that would allow me to view my 2x2's without my glasses so I can see the 
> full frame (edges get lost now when viewing with glasses).

Generally, you get extra points for being more nearsighted when you're 
building a viewer because you don't need as much optic help to get close 
to the transparencies.  However, in this case you probably have used, on 
the average, a 50 mm lens to take your shots so you want to get 50 mm away 
from the transparencies when you view them to get the right perspective.  
Since no one's anywhere near that nearsighted, you won't get much advantage.  
For instance, if you do want 50 mm, and your glasses correction is -3 diopters 
(unaided farthest clear distance = 1/3 m or 13.1"), then you could use a 
51 mm lens instead of a 50 mm lens.  Big deal.  So just buy 50 mm lenses 
from Edmund Scientific.  

Joel could tell you which lens has enough coverage but a couple of choices 
are #32323 which is 25 mm in diameter and 32496 which is 30 mm in diameter.  
>From Edmund, these lenses are about $40 _each_!  I wish I knew where to buy 
them cheaper.  You mount them with the flat side toward your eye.  If you 
put them in tubes sticking out of the viewer box, you can get your eyes 
closer to the lenses for better coverage.  You can also trip and put both 
your eyes out at once.

If you have astigmatism, then you'll also have to get your optician to 
grind a lens that corrects for this.  You can put that correction between 
the 50 mm lens and the transparency.

John B


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