[largeformat] formula for heligon

[Les Newcomer]

Okay so this isn't strictly speaking, largeformat, but the right people
are on the list.

I've been trying to get a fast 80mm lens fitted to a 2x3 Pacemaker Speed.

I picked up an 80 Planar (f2.8) but found that the bed wouldn't close
with that huge shutter on it and while it wasn't a real problem, I did
need to remove the rear cell to mount the lens.

I then found an 80 2.8 Heligon. the shutter much smaller, the front cell
glass is the same diameter but the rear cell is much smaller.

Kingslake says that this may be a Planar formula, but if that's true how
could they get away from the big rear end?

Ken hough suspected that this may actually be a Tessar, since Rodenstock
has been known to use the name Heligon much like Kodak used the name
Ektar--not to denote a lens formula, just a brand name.

He also noted that the front cell of a tessar won't project an image.
The theory of this being a Tessar would solve the mystery of the small
rear cell, but I was worried it wouldn't cover 6x7.

so I tested this mystery Heligon. The front cell DOES project an image.
Infact it's (very rough estimate) of 4" focal length.  The rear cell is 7.5".


So does anybody out there know what the specs are on an 80mm f2.8
Heligon? Will it cover 6x7cm?

LEs