My turn, Determining Curcuit Angle of View

[Ron Klein <panorama@xxxxxxx>]

The old photographers using cirkuts used a quick rule of thumb for
determining the degrees.  They would the pinion gear that they were using
for that particular lens and focus, and subtract one from the tooth number,
and this would give them the number of degrees per foot of film used.  It
probably isn't very scientific, but it does work well for determining the
amount of film used in a given photo. Hell, some photographers would add one
to the pinion number and it would work as well.  We are talking rough, and
adding one to the number would give them and extra amount of film to prevent
running out in a shot.

OK so you don't know the focal length, I'll bet that the old photos were
made using the original 10 1/2, 18, 24 Turner Reich lens that most #10
cameras had as original equipment.  The real focal lengths were considerably
different, being closer to 10 3/4, 16 1/2, and 21.  To make the story as
short as possible, the infinity pinion gears are usually 66, or 65 for the
10 1/2 inch lens, 43 or 42 for the 18 inch lens, and 33 or 32 for the 24
inch lens.  You should be able to calculate well with in your ballpark with
what I've given.

Also, if your images are 70 inches long, they would be well past a 360
degree view with the 10 1/2 lens, so I've already narrowed it down to two
choices for you if original equipment was used.  If the18 inch lens was used
you are looking at approx. 240 degrees for a 70 inch photo.  The 24 inch
lens would be close to180 degrees.  I might add that it is very rare to see
a cirkut camera from that vintage without the original lens combo, but it
was done.

Trust me on this, I've worked on more than a few cirkut cameras.

Ron Klein