Nikon began putting a rubber ring at the lens mount to prevent dust, dirt, and water from getting into the mount with one of the early revisions of the exotic telephoto lenses and has tended to put them on all but the lowest-cost kit lenses ever since. At this point, the following lenses have this ring:
- DX primes: 35mm f/1.8G, 40mm f/2.8G, 85mm f/3.5G
- DX zooms: 10-24mm f/3.5-4.5G, 16-80mm f/2.8-4E, 16-85mm f/3.5-5.6G, 17-55mm f/2.8G, 18-70mm f/3.5-4.5G, 18-140mm f/3.5-4.5G, 18-200mm f/3.5-5.6G, 18-300mm f/3.5-5.6G and f/3.5-6.3G, 55-300mm f/4-5.6G
- FX primes: all the f/1.4G and f/1.8G primes, the 45mm f/2.8D PC-E, 60mm f/2.8G, 85mm f/2.8D PC-E, 105mm f/2.8G, plus all the G- and E-type exotics (200mm to 800mm)
- FX zooms: 14-24mm f/2.8G, 16-35mm f/4G, 18-35mm f/3.5-4.5G, 24-70mm f/2.8 G and E versions, 24-85mm f/3.5-4.5G, 24-120mm f/4G, 28-300mm f/3.5-5.6G, 70-300mm f/4-5.6G (most recent version), 70-200mm f/2.8G and f/4G, 80-400mm f/4.5-5.6G VR, 200-400mm f/4G (both versions), and 200-500mm f/5.6E
Most of the more expensive Nikkors (e.g. f/2.8 zooms and the exotic telephotos) also have gasketing behind switches and focus display windows.
The following lenses have protective fluorine treating on the front element that tends to shed water:
- 16-80mm f/2.8-4E DX
- 24-70mm f/2.8E
- 300mm f/4E
- 400mm f/2.8E, 500mm f/4E, and 600mm f/4E
All that said, Nikon does not claim weather resistance for any of their lenses that I know of, other than the AW lens series for the AW1 camera.
As lenses get more and more electronics and motors in them, this can be a bit disconcerting to some. My experience says that most Nikkors are sealed well enough to be usable in light mist and rain without really being concerned, though.
Generally my rule of thumb is this: if I can’t keep the front element of the lens clean for shooting, I need to put the lens away or protect it.