
In answer to post #29
Let
k = negativetoprint distance
f = focal length
n = negative dimension (length, width, or any other dimension of interest in the negative)
p = projected dimension of n
p = ([(k + sqrt(k^2 – 4kf) )/2f] – 1)n
Example: k = 4270mm, f = 135mm, n = 56mm
P = ([4270 + sqrt(4270^2 – 4*4270*135)/2*135] – 1)*56mm = 1657mm = 65”
It’s not pretty, but that’s the way it is.
The calculation is much simpler if you use the lenstoprint distance.
In that case we’d let
u = lenstoprint distance
p = [u/f – 1]n
Example:
u = 4130mm
p = [4130/135 – 1]*56mm = 1657mm = 65”
Last edited by Ian C; 02012013 at 12:57 PM. Click to view previous post history.