Preventing focus rings from drying up, apertures from getting oily, bearings from being worn

Hopefully a simple question. I've started narrowing down my equipment to the things I want to keep in good shape and value. I store my lenses in humidity-controlled cabinets.

But I have noticed a few lenses I've used in the past have had stiff (55mm f2.8 AI-S) focus or dry (50mm f1.2 AI) focus rings. And I had a 24mm f2.0 nFD lens with a lot of play in the focus rings but I sold it off cheap.

I am trying to treat my gear well. What will allow me to prevent similar problems in the future? I figure the grease must be dried from heat, not from low humidity, since it's not water-based?

Policar said:

Hopefully a simple question. I've started narrowing down my equipment to the things I want to keep in good shape and value. I store my lenses in humidity-controlled cabinets.

But I have noticed a few lenses I've used in the past have had stiff (55mm f2.8 AI-S) focus or dry (50mm f1.2 AI) focus rings. And I had a 24mm f2.0 nFD lens with a lot of play in the focus rings but I sold it off cheap.

I am trying to treat my gear well. What will allow me to prevent similar problems in the future? I figure the grease must be dried from heat, not from low humidity, since it's not water-based?

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I think the grease on the helicoids of lenses changes over the decades. Either it dries out or liquefies, which is the cause of the aperture blades becoming oily. The fat that has turned into oil travels through the tube. You can't stop it, but cleaning and re-greasing is possible.

Some Canon FD lenses are known to have problems with bearings that wear out. Then the focus ring gets play.

Are humidity and heat factors? Is the position of the aperture ring and focus ring a factor? I just want to avoid this when I can, as CLA is expensive (particularly for cinema lenses).

I think you're right. The 55mm AI-S is known for both a greasy aperture and stiff focus ring. The one I tried had a clean aperture, I think, but very stiff focus. I will probably just pay for CLAs when I need them. But I want to try to be careful.

Policar said:

Are humidity and heat factors? Is the position of the aperture ring and focus ring a factor? I just want to avoid this when I can, as CLA is expensive (particularly for cinema lenses).

I think you're right. The 55mm AI-S is known for both a greasy aperture and stiff focus ring. The one I tried had a clean aperture, I think, but very stiff focus. I will probably just pay for CLAs when I need them. But I want to try to be careful.

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Heat and humidity are always an unfavorable combination for lenses and can also promote the growth of fungus.

But you shouldn't treat the lenses too delicately. The Nikkors in particular are built for tough use, they can take a lot.

You can also service lenses yourself; I will post further one or two reports on this here.

I would give valuable lenses to the workshop. Last but not least, this increases their value.

Some times the grease itself separated (broke) bad grease from the source, don't leave gear in an oven of a car.
It's like they say with cars the worst thing you can do is not drive it, the second worst thing you can do is drive it.
All systems will break down, entropy....

I've been handed Nikkor lenses from the early 60s that had never been serviced and were just beautiful in feel. Pentax lenses, same thing. The lubricants they used? Storage?

In general, modern greases are much better than older greases for longevity and not separating. But then you have to get the right combination of 'stickiness' and flow. I can't remember specifics right now, but I do remember hearing of lenses that needed grease to fill small gaps to prevent backlash and such. Grease was part of the design. Matching the combination of gap filling and proper stickiness is not easy. I know a guy who was a master in refurbishing antique guns and had a small jar of sperm whale oil because it was the only thing he could find that worked for certain mechanisms from the early 1800s.

Storage! And experience, of you or of the people servicing your lenses. Cinema repair people would be a nice resource since they probably are expected to match resistance, be consistent, etc. across lenses.

The specifications for grease tends to be quite broad. For example, the kind of damping grease used on lens helicoils had a range of -40C to 140C, from the Tribosyn 320 Damping Grease specification. Nye damping grease specifies separation and evaporation of 4% and .08%, respectively, at 100 C for 24 hours. It is highly unlikely that home storage temps is a problem. A car trunk/boot might get close to those levels, though, in a very hot climate. But that's still not a huge negative impact. It's not that the helicoid wears and gets loose, but that the grease changes and makes the helicoid loose or tight. As @Dan Daniel said, the damping grease is part of the design and it is htat grease that gives the "feel" to the focus. The simple fact is that these greases only last so long and need to be refreshed periodically. My Nikkor lenses tend to dry out about every 20 to 25 years. To me, there is little one can do to make mechanical devices last forever.... it's just a fact of life.