Cleaning aperture on Pentacon MC 1.8/50mm

BRunner · Joined: 29 Jul 2009 Posts: 705 Location: Czech Republic

After some time, second guide from me. This time I show you, how to clean stuck aperture blades on Pentacon 1.8/50, which is pretty common fail with this lens.
It's common lens, it's cheap and it's easy. Good to start with.
Again only assembly, disassembling is just reverse.

Clean the aperture blades and parts from oil with your favorite dish washing liquid and let them dry.

Put blades on place as shown on next picture

Put entire assembly inside lens barrel. It's the hardest part, best way is to turn barrel upside down and put it on aperture assembly. After third or fourth attempt you will surely succeed Wink

Then put on place three screws which holds the aperture assembly inside barrel. Don't tighten them now, because we need later adjust the aperture.

Now put back rear part, beware all balls, A/M switch and aperture control assembly.

Tighten the three screws which holds rear part of lens.

Now adjust the top aperture cover. At f1.8 should be the aperture fully open and you need to see hole size change even when stopping from f11 to f16. The fix the cover with tightening the three screws. Don't use to much force.

If it is necessary, add some grease to helicoid

Screw in the front lenses group

Screw on front filter ring and secure it with small screw

And lastly screw in the nameplate ring.

Enjoy your repaired Pentacon not only wide-open....

...but stopped down too Wink

martyn_bannister · Joined: 23 May 2010 Posts: 1151

Excellent series and a rally good result. Thanks for sharing.

I find that it is worth either finding, or making, screwdrivers which fit the screw slots exactly. I am sure it is not your doing, but several screws in you pictures bear the signs of being tightened with too small a screwdriver.

Attila · Expire: 2025-11-18

Many thanks for sharing!

sergioTM · Joined: 04 May 2017 Posts: 1