I've had the old Nikkor 180 mm f/2.8 ED manual (AIS) lens (the one with the golden ring) for almost 30 years and used it without problems for landscape and general photography. Only recently I tried it for the first time for long-exposure AP (with SW Star Adventurer and AP-modded Nikon D7000). To my frustration I realized that when pointed up (higher than appr. 45-50 degrees), the lens rotates the focusing ring past infinity almost immediately, sliding down under its own weight! I know it's supposed to focus past infinity, that's not the problem, but the slippery nature of the focusing ring. Obviously, for general photography the lens is never in such a steep vertical position, so I have never noticed it before.
I took the lens to authorized Nikon repair shop (the most experienced one in these corners of the world), and they told me that the only thing they could do is to play with the amount of lubricant inside the lens. They definitely did not not want to do it and strongly advised against it, because the focusing works so beautifully and smoothly otherwise.
Anyone else had this problem? Ideas? Just taping the focusing ring after finding perfect focus?
Another question related to the same lens (do not want to start another thread): On some CN threads and blogs (e.g. in this one http://www.astropix....NIKON_180MM.HTM by Jerry Lodriguss) people have recommended guidescope rings to support the lens (since it does not have a mounting collar). Is this really necessary? If the weight of the lens would cause too much flexure on the bayonet, I would presume that Nikon would have put a collar on it to begin with? Again, for general photography, with just the camera body mounted on tripod I've never had any problems. FWIW, I do use it only with Nikon bodies, so I do not need a Nikon-to-Canon adapter between the lens and the body, which obviously might make the combination more flexure-prone and stressful for the bayonet with the rather heavy, unsupported lens.
Edited by Axunator, 03 January 2017 - 08:48 AM.