REPAIR - Carl Zeiss Jena Pancolar 2/50mm

[stevemark]

This very Pancolar came years ago with a truckload of stuff from an old Swiss / German entrepreneur and "crazy collector" of cameras and lenses. Grown up in Eastern Germany by very poor Swiss parents, he had joined the Peenemünde rocket research facility when he was 16 years old, towards the end of WWII. Working directly under Wernher von Braun (the father of the Saturn moon rocket), he was involved in constructing / manufacturing / "programming" the guidance system of the V2 rocket. When the war had ended he knew enough about electronics to set up his own company after he came back to Switzerland. Money was never an issue for him; one of his friends told me that he regularly would go shopping (old cameras and lenses, that is) on Saturdays, with CHF 20'000.-- cash in his pockets - and that was in the 1970s!

Anyway, I got some interesting (though not rare) stuff from him at a very fair price, and this lens (attached to an Exacta) was one of the many lenses in those boxes. It was pretty dirty; there's some fogging and fungus, focusing is pretty stiff, and the aperture mechanism somehow was "disconnected" / not working. This very lens was built around 1961.


The Pancolar - originally sold as Flexon - was the first normal lens made in Eastern Germany (GDR / DDR) using righ refractive lanthanum glass. The difficulties encountered during computation and construction (1953-1957) are well documented by Marco Kröger (https://zeissikonveb.de/start/objektive/normalobjektive/pancolar2.html).

The Zeiss engineers not only had to enlarge the image field (50mm instead of 58mm with the Biotar), but also to improve the performance. And they had to circumvent the many previous patents issued for really famous f2 normal lenses from western Germany, such as the Leitz Summicron (1950), the Voigtländer Ultron (1950, by Tronnier), the Agfa Solagon (1950), the Schneider Xenon (1951), and the Rodenstock Heliogon.

Opening the lens is much easier than with the previous Biotar 2/58mm - just unscrew the four big screws on the rear:


The bayonet mount comes off:


To remove the aperture ring we have to remove this screw first:


The aperture ring comes off:


As you may know many of the CZJ lenses from the 1960 (as well as some from western Germany) have a mechanical display for the depth-of-field. Its mechanism with the small gear (cogwheel) is shown here:


It's easy to take it apart - don't loose the tiny cogwheel!


Now let's remove the optical block from the outer focusing mechanism. First we have to remove the (single!) guide:



Then we can take the lens block out. Be sure to mark the separation point so that you can re-assemble the lens without problems!


Focusing mechanism and lens block are separated:


The focusing mechanism can be dismantled further by removing this stopper screw:


Now unscrew the focusing mechanism (it took me slightly more than seven turns - count them for proper re-assembling, and mark the poition where the threads are separating):



Now the focusing mechanism is ready for cleaning and re-lubricating. I have used hot water plus household detergents and a toothbrush first, then acetone / toothbrush, and repeated the procedure 2-3 times. For re-lubing I have used Losimol 33B, a special grease for MF lenses with low viscosity. Do not apply too much grease - otherwise focusing will be stiff ...!!


Now the problem with the aperture ... Turns out that the aperture itself is working perfectly - however the mechanism coupling the shutter release with the aperture itself was de-coupled ... So I had to remove it:


Pretty soon it became obvious that the small lever had disengaged (re-connecting was no problem):


Cleaning the glass didn't go as planned - while the rear lens block was easy to clean, I wasn't able to remove the front lens name plate ... which meant I wouldn't have access to the tiny spot of fungus hidden at the rear of the first (=front) lens!

I'll try to make a special rubber tool which fits the name ring exactly, but for time being I have to live with that little bit of fungus. The lens performs admirably nevertheless: https://forum.mflenses.com/viewtopic,p,1591550.html#1591550

S

[stevemark]

Today I got this message / question from another user:

[RokkorDoctor]

[pleto]

#1


#2


#3


#4


#5


#6


#7


#8


#9


#10



These is the aperture block after dismantling. I could not get back the return lever in any functioning position. It was stuck when I bought it, I dismantled the block. I put back in plcae the blades, actuator can close the blades but the lever, the last thing I put back, got stuck at avery attempt.

[stevemark]

[Mike Deep]

I just acquired one of these for a song and got right to dismantling it. The helicoid, after removing the key, simply won't spin out? What am I missing?

EDIT: Scratch that, I got another one and used the first for donor parts.