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Sonnar 135/2.8 VERY slow aperture blades
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PostPosted: Wed Oct 05, 2011 3:23 pm    Post subject: Sonnar 135/2.8 VERY slow aperture blades Reply with quote
Ho Folks,

I got hold of a very nice Pentacon 135/2.8 (Sonnar?) but the aperture blades aer REALLY slow.

There is NO oil on the blades at all. I believe the actuating mechanism between the rear pin and the bit that goes round is very stiff. I can insert a probe and move the mechanism quite easily, but can feel the stiff grease.

Is this easy to fix? I paid very little money as the glass is in perfect condition, and I thought it was worth taking a chance.

Thanks for any info,

Graham


PostPosted: Wed Oct 05, 2011 3:56 pm    Post subject: Reply with quote
Easy to dissmantle and rebuild after. Not necessary to recognise oil on stopped blades, these auto-manual lenses are sensetive equipments , I think you will able to clean it.


PostPosted: Wed Oct 05, 2011 4:04 pm    Post subject: Reply with quote
Ok, I'll give it a try Shocked

...ahh, look! Someone did it already Very Happy

http://forum.mflenses.com/pentacon-auto-2-8-135-partial-disassembly-and-cleaning-t9836.html

and made a report Cool

Next time I just shut my mouth and search first Embarassed


PostPosted: Sat Oct 29, 2011 1:31 pm    Post subject: Reply with quote
Just bought a mint M42 Praktica CZJ 135mm f3.5 MC and I don't think it's ever been used and the blades are stuck...try banging the lens with my hand with the lens stopped down but that doesn't work, how do I get to the blades please Question


PostPosted: Sat Oct 29, 2011 1:37 pm    Post subject: Re: Sonnar 135/2.8 VERY slow aperture blades Reply with quote
GrahamNR17 wrote:
Ho Folks,
I got hold of a very nice Pentacon 135/2.8 (Sonnar?)


It's a Meyer Goerlitz lens, the more modern version of the Orestor 2.8/135.
Also known as "bokeh monster" Smile


PostPosted: Sat Oct 29, 2011 1:39 pm    Post subject: Reply with quote
Excalibur wrote:
Just bought a mint M42 Praktica CZJ 135mm f3.5 MC and I don't think it's ever been used and the blades are stuck...try banging the lens with my hand with the lens stopped down but that doesn't work, how do I get to the blades please Question


Careful, fixing aperture is tricky, if you don't know what you're doing you risk to waste the lens.
Try warming the lens up a bit over a not too hot termosiphon. If the oil did dry for non use, this might help.


PostPosted: Sat Oct 29, 2011 1:51 pm    Post subject: Reply with quote
Orio wrote:
Excalibur wrote:
Just bought a mint M42 Praktica CZJ 135mm f3.5 MC and I don't think it's ever been used and the blades are stuck...tried banging the lens with my hand with the lens stopped down but that doesn't work, how do I get to the blades please Question


Careful, fixing aperture is tricky, if you don't know what you're doing you risk to waste the lens.
Try warming the lens up a bit over a not too hot termosiphon. If the oil did dry for non use, this might help.


Thanks... I wouldn't dismantle the blades but just want to get them moving so I can use the lens in stopped down mode and not auto. Also have a Flektogon 35mm f2.4 MC in another thread with the same problem Sad

edit: I put the lens in my trouser pocket lets see what near blood temp will do Wink


PostPosted: Sat Oct 29, 2011 2:24 pm    Post subject: Reply with quote
Excalibur wrote:
Just bought a mint M42 Praktica CZJ 135mm f3.5 MC and I don't think it's ever been used and the blades are stuck...try banging the lens with my hand with the lens stopped down but that doesn't work, how do I get to the blades please Question

This might be useful
http://www.andrew.brown.dsl.pipex.com/articles/czj135svc/


PostPosted: Sat Oct 29, 2011 3:06 pm    Post subject: Reply with quote
peterqd wrote:
Excalibur wrote:
Just bought a mint M42 Praktica CZJ 135mm f3.5 MC and I don't think it's ever been used and the blades are stuck...try banging the lens with my hand with the lens stopped down but that doesn't work, how do I get to the blades please Question

This might be useful
http://www.andrew.brown.dsl.pipex.com/articles/czj135svc/


Thanks but that looks complicated, I only want to twiddle something to get the blades moving but if it means all that stripping down to get at them (blades) I'll end up with a headache. Sad


PostPosted: Sat Oct 29, 2011 3:13 pm    Post subject: Reply with quote
Excalibur wrote:
peterqd wrote:
Excalibur wrote:
Just bought a mint M42 Praktica CZJ 135mm f3.5 MC and I don't think it's ever been used and the blades are stuck...try banging the lens with my hand with the lens stopped down but that doesn't work, how do I get to the blades please Question

This might be useful
http://www.andrew.brown.dsl.pipex.com/articles/czj135svc/


Thanks but that looks complicated, I only want to twiddle something to get the blades moving but if it means all that stripping down to get at them (blades) I'll end up with a headache. Sad

You'll have to at least take the mount off and look at the pin mechanism. Sometimes it's not necessary to access the blades if they're clean and free. The springs sometimes become weak or the mechanism might need lubricating.


PostPosted: Sat Oct 29, 2011 4:21 pm    Post subject: Reply with quote
peterqd wrote:
Excalibur wrote:
peterqd wrote:
Excalibur wrote:
Just bought a mint M42 Praktica CZJ 135mm f3.5 MC and I don't think it's ever been used and the blades are stuck...try banging the lens with my hand with the lens stopped down but that doesn't work, how do I get to the blades please Question

This might be useful
http://www.andrew.brown.dsl.pipex.com/articles/czj135svc/


Thanks but that looks complicated, I only want to twiddle something to get the blades moving but if it means all that stripping down to get at them (blades) I'll end up with a headache. Sad

You'll have to at least take the mount off and look at the pin mechanism. Sometimes it's not necessary to access the blades if they're clean and free. The springs sometimes become weak or the mechanism might need lubricating.



Well I did take the mount off (fig 2 in your link) and prodded around but couldn't see anything that could be used to gently force the blades to stop down Sad

BTW it's a MC S=Sonnar and I'm scared to dig to deeply into the lens so I'll have to use it stuck at about f4.


PostPosted: Sun Oct 30, 2011 8:42 am    Post subject: Reply with quote
In Peter's link http://www.andrew.brown.dsl.pipex.com/articles/czj135svc/ and looking at fig 3....if you unscrew the tube the back lens comes with it and then you can see the blades, well I put drops of lighter fluid on the blades and it has made things worse as before it was stuck on f4 now it's gone to f3.5 and no amount of slapping by hand or operating the stop down pin (which you see on the back of a M42 lens) will make it stop down.
The lever which is used to set the aperture manually is floppy and does nothing (you can see it in fig 11), so I was wondering if a lens is stuck wide open and then you select the switch to "M" and then stop down manually does this ruin anything Question

Stop press: Problem solved.... stripped it down for the 4th time and used more lighter fluid and the blades are free......erm well see what happens when the lighter fuel evaporates, but I've set the aperture at f5.6 which is not a bad position to have a stuck iris.


PostPosted: Sun Oct 30, 2011 9:56 am    Post subject: Reply with quote
Yeah, if you don't dismantle the assembly then you have to almost flood the blades with fuel and keep working them until they're completely dry. A low-heat hairdryer helps, but the crucial thing is to keep the blades moving.


PostPosted: Sun Oct 30, 2011 12:36 pm    Post subject: Reply with quote
peterqd wrote:
Yeah, if you don't dismantle the assembly then you have to almost flood the blades with fuel and keep working them until they're completely dry. A low-heat hairdryer helps, but the crucial thing is to keep the blades moving.


AAMOI the Praktica flektogon 35mm f2.4 is very similar to the Praktica 135mm f2.4 sonnar for initial dismantling, the flektogon is even easier as you have a little swivel lever to operate the blades, and now I know what I'm doing, and in both lenses, you don't have to take the back lens off as you can drip the lighter fuel in from the outside...but my flektogon although mint needs a complete strip down as when the fuel dries the iris doesn't work properly.
The lenses and camera were stored in an aluminium case (which was corroded and the chrome bits were rusty ), in a garage for 20 years and amazingly there is no fungus anywhere. Anyway took a gamble and after haggling got the lot for £18 i.e. MTL5 with 50mmm Tessar, and 135mm f3.5 sonnar, and the flek all as new.


PostPosted: Sun Oct 30, 2011 1:22 pm    Post subject: Reply with quote
In general all Russian and east German lenses are cleanable well if you have proper tools. Japanese lenses are different , they did use glue to keep elements together and many of them unclean able. To clean blades not easy on any of them , need practice and patient , easy to waist hours to put blades together. I did try once and never more I rather put into lenses expert hands and pay around 20 GBP for service.


PostPosted: Sun Oct 30, 2011 2:02 pm    Post subject: Reply with quote
Attila wrote:
In general all Russian and east German lenses are cleanable well if you have proper tools. Japanese lenses are different , they did use glue to keep elements together and many of them unclean able. To clean blades not easy on any of them , need practice and patient , easy to waist hours to put blades together. I did try once and never more I rather put into lenses expert hands and pay around 20 GBP for service.


Well you are lucky for about £20, in the UK labour costs are very expensive although it would be nice if we could find an old retired camera technician who just wants some spare money for cigarettes and beer Wink


PostPosted: Sun Oct 30, 2011 2:20 pm    Post subject: Reply with quote
Laughing If you send here two -three lenses postal costs to both way another 20 GBP , my pro repair man accept lenses by postal service.

http://www.mflenses.com/camera-service.html


PostPosted: Sun Oct 30, 2011 5:35 pm    Post subject: Reply with quote
Excalibur wrote:
...but my flektogon although mint needs a complete strip down as when the fuel dries the iris doesn't work properly.

That's understandable. You need to wash away the "muck". You can't use large volumes of petrol but warm soapy water is cheap and safe. I've serviced quite a few Sonnars and Flektogons, and in some of those it was necessary to clean the aperture assembly. The warm soapy water method worked well.


PostPosted: Sun Oct 30, 2011 5:54 pm    Post subject: Reply with quote
Attila wrote:
Laughing If you send here two -three lenses postal costs to both way another 20 GBP , my pro repair man accept lenses by postal service.

http://www.mflenses.com/camera-service.html


That's worth knowing...thank you
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