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M42 CZJ 135mm 3.5 aperature ring not working
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PostPosted: Fri Jul 17, 2020 3:22 pm    Post subject: M42 CZJ 135mm 3.5 aperature ring not working Reply with quote

Hi,

I have just started shooting with old manual lenses, so I'm very much a newbie to his.

I've aquired a M42 Carl Zeiss Jena 135mm F3.5 in great (outside) condition. The problem is that turning the aperature ring does absolutely nothing. However, setting the aperature to M closes it down nicely. Setting it to A, it opens up and closes smoothly when I press the pin at the rear.

So it seems the blades work fine, but the ring has lost its connection to them (please correct me if I'm wrong).

Now do you think this is likely something a complete layman like me has a decent chance of fixing himself (and if so, how?) or should I rather get a professional or, probably more cost efficient, sell it and get a new one?

Bjoern


PostPosted: Fri Jul 17, 2020 6:05 pm    Post subject: Reply with quote

It sounds like its working just fine.
Switch the lens to M & the linkage should work perfectly.

It's easiest to focus with the aperture wide open (more light & the shallower DOF makes spotting focus easier) to enable this several approaches were used among M42 lenses
There are several types of M42 lens setup:
The earliest where typically 'pre-set' - with two aperture rings only one being connected to the blades the other set the smallest aperture the blades would go to. The blades could be moved to the pre-set aperture without having to look at the ring.

Then an auto pin was added which the camera could push in just as the mirror flipped up, closing the aperture only as the shot was being taken. To begin with these auto lenses had a switch to change them to manual so they could be used on older M42 cameras that didn't have the pin. This is the type you have. AFAIK no M42 adapters have an ability to push in the pin just as the shot is taken.

Some of the later M42 lenses have an auto pin but no manual switch (by the time they were made most people had cameras that could operate the pin) This type are slightly more of a pain to adapt needing something to hold the pin in - this can be a lip on the adapter, a little wooden wedge, a spot of glue... So far I've avoided them
Happy Dog


PostPosted: Fri Jul 17, 2020 6:30 pm    Post subject: Reply with quote

Many thanks for the reply. I'm afraid I did not express myself correctly before, sorry!

When I wrote "setting the aperature to M closes it down nicely", I meant to say that the aperture closes down completely to what I assume is F22 (but snappily without delay), irrespective of where the ring is set to. It also does not change when I turn the aperture ring. The pin in the back is without pressure on M (which I guess is correct?).

This means there is something wrong, does it not?


PostPosted: Fri Jul 17, 2020 6:58 pm    Post subject: Reply with quote

Welcome ulrichsson

Sounds like as you suspect the linkage from ring to diaphragm doesn't work as it should, something came loose or broke, likely the former. Depending on your skill level it may be easy to open the lens and fix it -- everybody had a first time -- M42 135/3.5 are typically simple construction.

There should be later replies here. The forum may already have a tutorial. Search also youtube.


PostPosted: Fri Jul 17, 2020 7:11 pm    Post subject: Reply with quote

ulrichsson wrote:
Many thanks for the reply. I'm afraid I did not express myself correctly before, sorry!

When I wrote "setting the aperature to M closes it down nicely", I meant to say that the aperture closes down completely to what I assume is F22 (but snappily without delay), irrespective of where the ring is set to. It also does not change when I turn the aperture ring. The pin in the back is without pressure on M (which I guess is correct?).

This means there is something wrong, does it not?


I'm afraid you're right. Describing yourself as a newbie made me jump to the newbie solution.

It may well be a relatively simple fix, but it might still be more than you fancy trying yourself, much depends on how handy you are. Good luck!


PostPosted: Fri Jul 17, 2020 8:34 pm    Post subject: Reply with quote

Thanks to both of you!

I think I'll give the repair a shot myself. I'm not the most nimble-fingered person, but also not completely hopeless and it would be a nice skill to acquire.

I'll search the forum and youtube for advice. I assume there will also be something on what equipment to get.


PostPosted: Sat Jul 18, 2020 10:39 pm    Post subject: Reply with quote

I fixed one once, (the famous no 100000000). Was an easy job and I'm as cack handed as they come


PostPosted: Sun Jul 19, 2020 11:57 pm    Post subject: Reply with quote

That is reassuring! I have ordered a pack of screwdrivers and I'll check what else I need and give it a go when I have a free weekend.

P.S.: Loving the avatar!


PostPosted: Mon Jul 20, 2020 7:42 am    Post subject: Reply with quote

[quote="ulrichsson"]That is reassuring! I have ordered a pack of screwdrivers and I'll check what else I need and give it a go when I have a free weekend.

P.S.: Loving the avatar![/quote]

A spanner wrench will be needed.