button on 200mm f/4 Nikkor-Q lens hood ???

The last version of the 200mm f/4 Nikkor-Q lens has a chrome button at the base of the built in lens hood. See for example, the photos in the link below...

https://www.destoutz.ch/lenses_telephoto_200mm.html

What is this button for and how does it work?
I recently bought one of these lenses and I cannot figure out what this button is for or how it works...

It seems like it has something to do with the lens hood, ostensibly a lock mechanism or something but, I cannot figure it out. Anybody know for sure or have an instruction manual?

TiA.

Venturing a guess - It looks like a lock button for the sliding lens hood. Push button down, slide lens shade forward until it locks in place. Push button down to reverse the procedure. Keeps the hood from sliding forward when not needed.

I watched a video on YouTube where a guy (Richard Haw, a member here) disassembled one of these lenses. It is clear now that the feature in question is not a button at all but a spring housing. There is a spring and small steel ball under it that, when the lens hood is extended, kinda softly locks the lens hood in place. Its not really a lock at all because, naturally when the lens hood is pushed back, the spring allows the little steel ball to pop up out of the channel around the rim of the lens.

mmmm...thar be a lotta words for a simple idea. Hope that makes sense.

And what about a little hole above the "buton" ?

vlasta said:

And what about a little hole above the "buton" ?

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I'm not sure but looking again at Richard Haw's YouTube video, where he disassembles this lens, it looks like it might be an access hole to allow one to get at a screw beneath the hood (?).

Mines a little limp.....shade tube that is.
How does yours perform? Im not fussed on mine, but to be honest havent used it much. They maybe cheap for a reason.

awty said:

Mines a little limp.....shade tube that is.
How does yours perform? I'm not fussed on mine, but to be honest haven't used it much. They maybe cheap for a reason.

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I just got it. Arrived earlier this week. Picked it up from KEH in BGN condition. As might be expected, it looks almost new. Once extended, the shade stays put and takes a bit of force to move it back to the stowed position.
I've got a roll of FP4+ in one of the Nikons and am kinda waiting to get away from the house to give it a spin but...may need to try it closer to home.
I've wanted one of these for a long time...something about all those photos of Vietnam war photo journalist.

How does your perform optically? They're supposed to be very good.

awty said:

Mines a little limp.....shade tube that is.
How does yours perform? Im not fussed on mine, but to be honest havent used it much. They maybe cheap for a reason.

Click to expand...

"Mine's a little limp" too, but thought it was because of my age
I

I just got one on Saturday - I was puzzling over the same thing. I can't find anything that the little hole lines up with though. I did notice that the hood works very smoothly and that there are no marks on the underlying surface from the ball bearing riding up and down on the lens barrel. Thanks for the explanation!

Andy