Re: Wildlife in 3D

[P3D John Bercovitz <bercov@xxxxxxxxxx>]

Dave W writes:

> I'm very interested in shooting wildlife in 3-d, but it is
> usually difficult, often impossible and occasionally
> dangerous to get close enough to use "short" lenses. And
> Does that mean I'll have to have Dr. T make me a custom Red 
> Button with 200mm lenses? 

In a word, yes.  You know how 2D photos taken with 500 mm
lenses look flat?  I mean it looks like the bear is painted 
on the hill behind it?  Well in stereo you get exactly the 
same effect and believe it or not, the effect is also of the 
exact same magnitude numerically speaking.  So you get good 
reinforcement of the distortion.  Now the brain will fight 
this because the brain knows the bear ain't painted on the hill.  
But with a 5:1 ratio of camera lens length to viewer lens length, 
you gotta be able to see the distortion!

> And custom lenses for projecting?

Nah, you just stand farther from the screen.  You want the angle 
subtended at the eye to be the same.  So if the tranparency (as
mounted) is 28 mm wide and the lens was 200 mm long, then you 
want to stand 200/28=7 screen widths from the screen.  That's 42'
from the screen if you have 6' screen.  That's a fur piece.

Would you consider a remotely-controlled armored Realist?

Dr. T writes:

> Don't worry about perspective distortions, etc.  Better alive with
> an image that fills the frame than dead or with an image too small 
> to make out.

Given a choice between having distorted stereo and getting et by a bar,
I'll go with Dr. T's advice!

John B


------------------------------