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Shen45
4-Aug-2007, 00:59
A friend here in Adealide has given me on loan a a Carl Zeiss Jena Protarlinse in a compound shutter.

It doesn't have an aperture scale as such only a scale that I assume is the mm opening size of the iris. This I assume when divided into the focal length of the lens group gives a working apeture.

The two element groupings are a 35cm and a 48cm.

I know nothing about this lens but the glass is in amazingly beautiful condition and the shutter works.

I haven't made a lens board for the lens as yet, that is tomorrows project but with both lens groups fitted to the shutter it aeems to be a shorter focal length than the 35cm ???? If it is does anyone have an idea what ength it may be?

Any information on the lens would be appreciated.

Steve
Ole Tjugen
4-Aug-2007, 02:27
Satz-Protars commonly had apertures marked in millimeters opening, since there were several cells that could be combined in one shutter. A triple convertible may have three aperture scales - add a third cell, and there just isn't room for the six aperture scales needed!

anyway: A 48cm and a 35cm protar cell combined gives a 23cm f:7.7 combined lens.
Jim Galli
4-Aug-2007, 09:54
Steve, easier than you think. Simply focus, measure gg - aperture distance - dive the mm scale into this and it's your aperture. ie. focused at infin, 230mm set the aperture to 10.5mm. 10.5 inot 230 = 22. F22 Focus the 48cm group at 70cm and set the mm dial at 11mm 700 divided by 11 = 64 you're at f64


BTW, they are wonderful lenses. It'll cover 8X10 easily at the combined groups and you can get a 42cm group for it sometime to make more combinations. They were corrected so well you can mix and match from most any era of mfg.
Shen45
4-Aug-2007, 19:13
Great info, thanks Jim and Ole. I have cut a new lensboard this morning and will be out this afternoon to try it out. The serial number is 918700 [350] and the 480 is 918828. Anyone have any ideas on the age of the lens? The shutter is running slow but appears to be consistently slow so I can work around that.
Ole Tjugen
5-Aug-2007, 02:59
918xxx is 1928, according to Thiele. :)