Which Nikon lenses are non-plastic?
Those protruding metal knobs were used so old cameras could determine what aperture was being used (a little rod from the camera fit into the middle of the knob and when you moved the aperture dial, it moved the rod)
There are many others, like the 85mm f/1.4D, 300mm f/4D and 80-200mm f/2.8D. I think the 105mm f/2 DC and 135mm f/2 DC as well. and the 28mm f/1.4D...
It is pretty easy to tell from pictures once you do some research.
Speaking of which, this website has pictures of practically every Nikon F lens.
Visit my Flickr!!
I own two lenses which are older than I am.