Stuck aperture blades on Flektagon 35mm 2.4

oldschool · Joined: 18 Oct 2016 Posts: 17

Can anyone help me free up the aperture blades on the Carl Zeiss Flektagon 35mm f/2.4?

The Aperture is mainly stuck open. In A mode the rear pin has resistance and when pressed the blades do not move. In M mode the pin has no resistance and does nothing.
The aperture ring does nothing in either mode.

I have removed the rear case and I can get the blades to open and close by simulating M mode to release the rocker spring tension and then pushing the lever underneath to move the blades.

Anyone have any experience of this? Appears to be a common complaint but i cant see any guide to fixing.

Thanks

oldschool · Joined: 18 Oct 2016 Posts: 17

OK I worked it out and all now works perfectly.
1. dissasemble lens as here - http://www.kolumbus.fi/uusilehto/img/lenses/zeiss/disass/slides/lens.html
2. Follow step 9 in the cleaning guide here - http://www.aprd31.dsl.pipex.com/articles/czj135svc/
3. I should probably loosen off and realign focussing barrel but I didnt.

SonicScot · Posted: Fri Mar 03, 2017 12:26 am Post subject:

I would suggest that you always keep the blades closed when you're not using it. I've done that ever since fixing mine, it hasn't happened since.

Excalibur · Expire: 2014-04-21

Thanks for the link... my CZJ 135mm Sonnar has a peculiar problem for focussing in that I've taken the back off and re-assembled and it would start from infinity, but when focussing back to min distance, it then only goes back to 6ft (hits a stop).....so I have to study the instructions on how to set it i.e. min distance to infinity.

hasan · Joined: 12 Mar 2007 Posts: 313

Excalibur · Expire: 2014-04-21

hasan · Joined: 12 Mar 2007 Posts: 313

In http://www.aprd31.dsl.pipex.com/articles/czj135svc/

following may be the hint you are looking for:

..Set the mode to (A). The aperture ring should not function, if it does then you mis-aligned the mode selection lever when putting the case back on. Set the mode to (M). The aperture ring should stop the lens up and down freely. Test the focus. This is where you find out whether you got the infinity adjustment correct. You should be able to focus back to infinity and down to just below 1m, hitting a hard stop at each limit. If you either can't reach infinity, or the focus barrel screws all the way out past 1m then your infinity adjustment is wrong and you need to go back and set it again paying particular attention to the configuration in figure 13. The first time I took this lens apart I wasn't aware of the importance of the adjustment screw and had to reset it by trial and error. It took ages.."

hasan · Joined: 12 Mar 2007 Posts: 313

@oldschool
sorry for hijacking your thread.

congrats, by the way!

proplus · Joined: 20 Sep 2018 Posts: 3

Gonzoo · Joined: 29 Mar 2010 Posts: 231

If the blades are clean you should be able to operate the aperture - if it is assembled correctly. Can you post a picture of the aperture?

proplus · Joined: 20 Sep 2018 Posts: 3

Gonzoo · Joined: 29 Mar 2010 Posts: 231

First I thought that the spring attached to the aperture lever that pulls back the aperture blades is missing. But I saw it still attached ealier in the video. Maybe there is something wrong with the spring tension - it might be to weak to pull the aperture shut. Also there is still some oil on the blades.

My advice would be to disassemble the aperture completly to get to the bottom if the problem. This way you can get it cleaned properly. Reassembly might be a bit frustating though Smile

To get an idea of the process have a look towards the end of this page: http://forum.mflenses.com/cleaning-aperture-czj-tessar-105mm-f3-5-t75857,highlight,%2Btessar.html

The lens is different but the mechanism is basicly the same.

proplus · Joined: 20 Sep 2018 Posts: 3

Good news, its actually an easy fix, unless you accidentally misalign and/or loosen the aperture blades.

At 2:52 in the video you'll see me rotating the silver ring within the aperture mechanism, it is underneath this ring that a tiny spring has detached on one end (its simple enough to figure out where the loose end goes). Once reattached, aperture works perfectly again.

To remove the metal ring, you first need to remove the aperture arm, and the unscrew the black covering via the 2 notches within the mechanism at 2:53 with a lens wrench. This covering presses down onto the aperture blade axis, so be careful from this point in not disturbing the aperture blades.

Its actually not a great design with how this spring is attached; the notches at both ends to where the spring attaches are not tapered or have any grip on them to firmly attached the spring ends. One good shake of this lens and the spring will detach and you'll get the common problem of the aperture being stuck wide open.

kiddo · Joined: 29 Jun 2018 Posts: 1121

Hi, anyone could tell me what's the size of the aperture ring ball, as I've got a clickless lens.

Gonzoo · Joined: 29 Mar 2010 Posts: 231

It's something in between 1.5mm and 2mm. IIRC Pentacon lenses feature a 1,8mm ball bearing diameter, you might try to salvage one from an inexpensive 50mm. See discussion here: http://forum.mflenses.com/lost-the-aperture-ball-bearing-how-to-found-out-its-size-t63678.html