[photo-3d] Nearpoint table

[Ralph Johnston/Linda Sherman <copley@xxxxxxxxxxxxxxx>]

To avoid window violations, it is important to know the nearpoint, or where
the
window is.  You can them imagine a wire frame out in front of the camera which
nothing can touch.  I made up a table for my stereo cameras and sorted them
from near to far.  (I don't have the RBT S1)  To get the columns to line up
you
may have to switch your mail program to fixed font.  Or cut and paste it into
MS Word and adjust the tabs there.  Every column lined up when it left here!


Here it is:

Camera base base focL nearpoint nearpoint  
 Perf mm mm m ft 
Rittai 4 19 25 0.4 1.3ISO Duplex NA 30 35 0.9 2.9
RBT X4B 16 75 16 1.0 3.3
Rittai 12 57 25 1.2 3.9
RBT S1 45 12 57 35 1.7 5.5
*Fed 7perf 14 66 32 1.7 5.8
Realist 15 71.25 35 2.1 6.8
*RBT X4B 16 75 35 2.2 7.2
*Cosina C3 NA 305 16 4.1 13.3
*RBT X4B 16 75 70 4.4 14.3
Olympus XA2 NA 305 35 8.9 29.1
Cosina C3 NA 305 70 17.8 58

* cameras are current preferred.

305mm bases are a bar with 12" separation

The Rittai is a 4-lens lenticular camera.  The inner pair of images is spaced
at 4 perf while the outer pair is spaced at 12 perf.

The ISO Duplex uses 120 film in 630 format and spaces the images at half of
the
6cm width.

STEREO BASE FORMULA
'near point distance = (focal length x stereo base) /parallax'

Books recommend 1.2mm for 24x36 and 3mm for 6x6 negs, say 1/30 of horizontal
side or roughly 2° viewing parallax

Hope this helps someone.  I use it a lot and even write the nearpoint on a
label and paste it one the camera or twin rig.

Regards -Ralph

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