Re: photographing small; projecting big?

[T3D john bercovitz <bercov@xxxxxxxxxxx>]

Scaling works linearly in all three dimensions with lens shift.
So if you want to use a 1/3 scale model, instead of using your 
65 mm perspective point separation, use a 22 mm separation.  
Coincidentally, I was just taking a picture of a bust of Lord 
Byron yesterday.  The bust's forehead measured 2" across so I 
used a 22 mm separation.  For 3" "action figures", I've used 
3 mm separation with great success.
 
A side comment: 35 mm is an awfully short lens.  I usually 
figure by height since 4, 5, 7, etc perf formats are all about
23 or 24 mm high and so using height, the same calc will do for 
all formats.  We can see that distance/height ratio from the 
lens toward the film with a 35 mm lens is 35/23 = 1.5.  So the 
distance/height ratio of the camera looking into object space 
is also 1.5.  That means when you view the image on the screen, 
you need to sit 1.5 times the image height away from the screen.  
That's awfully close.  Imagine seating a whole audience 6 feet 
away from a 4' high screen.  Or 18' away from a 12' screen.  
(It does get easier as the screen gets larger to cram a 
significant number of people into the audience space because the 
size of a person does not change with screen size.)  
 
John B


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