Quick Guide

Interchangeable lenses
Standard lenses
Jena Bm 80mm,f2.8 automatic diaphragm
Meyer Primotar E 80mm,f2.8 pressure diaphragm
Supplementary lenses
Jena Flektogon 50mm,f4 automatic diaphragm
Jena Flektogon 65mm,f2.8 automatic diaphragm
Jena Bm 120mm,f2.8 automatic diaphragm
Jena S 180mm,f2.8 automatic diaphragm
Meyer Telemegor 300mm,f4.5 manual pre-set diaphragm
Jena Mirror lens 1000mm,f5.6
Standard lenses
The standard Jena Bm lens is equipped with automatic spring diaphragm, and the Meyer Primotar E with a pressure diaphragm. The
mechanical performance of these two lenses is somewhat different. To check the depth of field on the image field lens with the Jena Bm
lens you exert continuous pressure on lever (16) at the right hand side of the lens mount. With the Meyer Primotar E on the other hand, the
diaphragm setting ring has to be moved from the red mark to the black mark. The diaphragm thus closes to the pre-set value. As long as the
red dot stands against the red diaphragm index mark the automatic diaphragm mechanism is in operation and the widest aperture will
always be set when the shutter is cocked. When the black dot on the front setting ring stands opposite the diaphragm index mark, the field
lens image may be viewed with the diaphragm on pre-set stop. For the purpose of brightening up to finder image the focusing aperture of
the Primotar E is somewhat larger than f3.5, whereas the exposure is made at the actual pre-set opening.
Supplementary lenses
On supplementary lenses not equipped with an automatic diaphragm as, for instance, the 300 mm Telemegor f 4.5, you press the setting
ring directly behind the diaphragm scale backwards and adjust it so that its mark stands opposite the desired diaphragm numeral, where it
clicks in.