10-06-2024, 09:06 AM
(This post was last modified: 10-06-2024, 09:08 AM by MLonlooker.)
Hi stoppingdown,
Regarding your Nikon contacts problem, I had the same issue especially when I went to sell my Nikon AF-S 500mm F4D ....... no AF at all, I cleaned the contacts with alcohol and it sort of improved, but would revert to not working reliably again.
As I was selling it, it had to work, I taped up the rear exit so as protect the optics and went about cleaning with a fine scotch-brite quite briskly until the contacts were shiny again ..... low and behold when I mounted the lens on the D750 it worked like new.
Alcohol cleans grease but does not touch micro corrosion, which is the problem, why Nikon don't gold-plate the contacts I'll never know? ..... a brisk clean wit a scotch-brite would have cured your two 300mm F4 lenses for sure.
This corrosion issue is also what causes AF motors to squeak and eventually stop focusing, the stator has a crystal coating which can form a micro-corrosion in damp conditions .... if you go back and forth with the focus ring, it will start to function again, keep going and the micro-corrosion wears away and the lens focuses normally again.
Motto of the story is to keep your camera gear in dry conditions; no dampness, no corrosion!
Regarding your Nikon contacts problem, I had the same issue especially when I went to sell my Nikon AF-S 500mm F4D ....... no AF at all, I cleaned the contacts with alcohol and it sort of improved, but would revert to not working reliably again.
As I was selling it, it had to work, I taped up the rear exit so as protect the optics and went about cleaning with a fine scotch-brite quite briskly until the contacts were shiny again ..... low and behold when I mounted the lens on the D750 it worked like new.
Alcohol cleans grease but does not touch micro corrosion, which is the problem, why Nikon don't gold-plate the contacts I'll never know? ..... a brisk clean wit a scotch-brite would have cured your two 300mm F4 lenses for sure.
This corrosion issue is also what causes AF motors to squeak and eventually stop focusing, the stator has a crystal coating which can form a micro-corrosion in damp conditions .... if you go back and forth with the focus ring, it will start to function again, keep going and the micro-corrosion wears away and the lens focuses normally again.
Motto of the story is to keep your camera gear in dry conditions; no dampness, no corrosion!