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I recently bought a Jupiter 37am lens, which is a 135mm f/3.5 retro telephoto lens. The lens looks good and the glass is clean, but I have an issues with it.

The focus ring is very stiff and hard to turn. I noticed some dark lubricants leaking from the back of the lens, near the mount and I guess that it's over-lubricated. I am worried that the lens may be corrupted or damaged. Is this normal for this lens or I should ask for refund?

Has anyone else experienced this problem with this lens? Any advice or suggestions would be appreciated. Thank you.

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user2085899
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Jupiter 37AM is an old, soviet-era lens. It has a pre-set aperture mechanism, that amount of old grease is perfectly normal for that lens. Even if there are oil on the aperture blades, due to its pre-set aperture mechanism, it does not affect anything, even when used on native-mount M42 cameras. On digital cameras, it can not affect anything in any way, because it is used with an adapter.

The stiffness of the focus ring also indicates that it sat unused for quite some time. To get it less stiff, slowly rotate the focus ring back and forth through the whole range as much as needed, to redistribute the grease through the focusing helicoid. It should start to feel less stiff after a few times.

elkarrde
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Over greased and probably the wrong viscosity is it's difficult to turn. I'd take it apart, clean out what's there and re-grease with something like a #10 helicoid grease.

AJS
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    Nope, that's the grease it was built with, and it's within the specification. It's just old, and it sat unused in who-knows-what conditions for decades. Sure, taking it apart and relubricating would help - if you have the tools and the skill to do that reliably. – elkarrde Oct 05 '23 at 12:10
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It's a widespread problem with a lot of USSR lenses - they use lubricant which hardens over time and must be replaced.

Euri Pinhollow
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