Discussion in 'Nikon' started by Erik-Christensen, Aug 21, 2021.
Hyperfocal distance at a certain aperture perhaps?
I really don't know but the notch is only with lenses that have very narrow focusing ring. I guess perhaps it's there so you can attach a larger focusing ring if you are into manual focusing.
Curiouser and curiouser. The manual of these lenses would most likely describe all the parts of the lens. If no one can locate a manual, there are some on eBay. Do let us know.
Trouble is, if it has no function for the user, it won't even be mentioned in the manual.
..and the fact that there are so many venerable Nikon users here that have no clue to what it's for, kinda implies it has no function for the user!
But I still want to know.
I have asked Nikon again - different organization
Not far off the truth I suspect.
I can vaguely dredge up memories of an early AF system that Nikon came up with before the 'screwdriver' attachment built into their lenses.
This prehistoric lash-up consisted of external AF sensors and a robotic lens twister that was matched to only two specially machined lenses when it first came out (one was an 85mm lens, and the other might have been a 200mm, I really can't remember that clearly). Anyhow, the contraption was heavy, bulky, expensive, and probably didn't work that well. So sales must have been dire.
Getting to the point. My guess is that the notch on early AF lenses was there to make them compatible with the above autofocussing robotic-arm contraption.
Also, you have to remember that consumer cameras are only part of what the erstwhile Nippon Kogaku group produce(d). I suspect that their industrial machine-vision department also had a use for lenses that could be externally robotically focused.
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