Re: ortho seat question

[P3D John Bercovitz <bercov@xxxxxxxxxxx>]

> Here's my question:
> Let's say you had two projectors, one with 5" lenses and
> one with 4" lenses.  If you set up both projectors so the
> on screen images are exactly the same size and in the same
> position, would the ortho seat be different for each projector?
> If not, then the ortho seat must depend only on image size, and
> not projector distance.

That's not a question, that's the answer!  Generally speaking,
the image, whether it's 5p or 7p, is 23 or 24 mm high and was 
taken with a 35 mm focal length lens.  That's about 1.5:1.  So 
all you need to do, regardless of which of the two formats you 
are viewing, is to step back 1.5 times the image height on the 
screen and Bob's your uncle. 

John B


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