View Full Version : Jupiter 12 on Kiev: Smooth off camera, rough on camera.
Yesterday I received a used Jupiter 12 from 1970 together with the corresponding finder. Off the camera the lens focusses 100% smooth as it has been recently relubed. But when I put it on the camera (Kneb 4am), focus is smooth with a bit more resistance until about 2m. Then it gets a bit stiff and again easier to turn at about 1,5m. No real problem here, as long as I focus via the lens, but next to impossible on the cameras focus-wheel.
The camera focusses fine with the Helios 103, helicals seem to be a bit dry and have a small amount of play as about any well worn lens-helical but run freely without any change in resistance.
Do I have to live with that kind of behaviour, will a cla of the camerras helical fix it or is there any shortcut to remedy this?
I don't know about the Kiev version, but I had a similar problem with a J-12 on a Fed-2. It was caused by the rangefinder arm in the camera getting fouled against the side of a rear part of the lens - just enough to make it stiff to focus. I solved it by bending the rangefinder lever upwards slightly (which can then require recalibration of the rangefinder - I was lucky and mine was still fine). I don't know if that's your problem too, but it might at least be worth looking for it - I'd suggest inspecting it with the back off to see.
CLA of the focussing helical of the lens should cure overall stiffness. Stiffness at distances closer than 1.5m or so could be due to the standard lens bayonet lock (the spring to hold the 50mm lenses in place) coming in contact with the lens mounted on external bayonet.
My inital reaction is that if the lens is smooth off the camera but not when attached then the camera may be at fault, or as I found with some H-103s that the lens may be 'just' fouling the insides of the camera. In my case one Kiev had been touched up with matt black paint inside and the minute extra thickness was enough to make one H-103 unusable on one but not the other. I gently scraped a little black off the side where no light ever goes ( :-) ) and they are now interchangeable.
Just a thought.
I have this issue as well. My J-12 is perfectly smooth off-camera and has a slight tight-spot when mounted. Looks like it's a common problem!
..........Do I have to live with that kind of behaviour, will a cla of the camerras helical fix it or is there any shortcut to remedy this?
In my opinion CLA of the helical mount is not only very easy (see KSS) but mandatory. The "trap" waiting for you at this stage is called "grease". Use a bit of oil until the helical mount moves ABSOLUTELY free. It will not be achieved with grease, unless you do it with Russ Pinchbeck, at his home.
As for the J-12, let's see if you can run away from the total dismount explained at the KSS. Against all other folks that ill say I am not right, apply A BIT of solvent to the rear parts metal parts and you can also release the spring (see KSS) and apply A BIT of solvent again. At this stage you are not looking just for a soft rotation but for an ABSOLUTELY FREE rotation of the distance scale.
BUT, USING YOUR COMMON SENSE, IF THE J-12 DOESN'T IMPROVE TO ABSOLUTELY FREE MOVEMENT DON'T FORCE IT BY INCREASING THE DOSIS OF SOLVENT, because by using just a bit, you are already making an infraction.
It is expected by me that by the combination of both focused CLAs, your J-12 once mounted on your camera will not rotate as an Helios, BUT REASONABLY SOFT.
It this doesn't help you will have to perform the full KSS dis-assembly of the J-12, which I avoided, due to not owning a spaner to deal with the dangerous front element.
Same problem with J-8 on Zorki 3M
Regarding Ruben's advice - I wouldn't do it. Kiev mount J-12 is easy enough to disassemble only with (reasonably thin) needle nose pliers.
Neither oil nor a solvent will help here. Oil migrates easily, and solvent will evaporate and you're back where were before.
Same problem with J-8 on Zorki 3M
If LTM lens is hard to turn when mounted and easy when off camera - it's because of dry grease. A CLA will solve that.
This can also be caused by the RF cam of the J-12 when it makes contact with the internal mount of the Kiev. The RF cam is spring-loaded and must move freely with the internal mount of the Kiev. If it does not move freely, it causes this unevenness. Holding the lens in your hand, move the "spindle" "RF Cam" ie part that makes the connection with the internal helical of the camera. If it is stiff and uneven, dry flood cleaning it with some lighter fluid.
Worked for me.
Thank you to everyone for their input. I tried Brian's recommendation but unfortunately nothing changed and the spring loaded back part of the lens seemed to slide freely anyway (except when not pushed on at an angle). I will not go ahead and disassemble lens or camera at this point as I'm afraid to aggrevate the lenses or cameras condition to solve a minor problem. The binding at 2m is rather weak and goes nearly unnoticed in real life use as long as I don't try to use the focus wheel on the camera.
I decided to live with it as long as it doesn't get worse. Thanks again!
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