Small button on lens mount

[Bikerbrent]

Greek to me! Not sure what a "screw drive mechanism" is in reference to a camera and auto focus.

If your camera had a built-in autofocus motor (which the D5500 does not), then this is where the screw drive for the lens autofocus system would be. Since the D5500 does not have a autofocus motor built in to the body, then it does NOT have a screw drive to drive the lens autofocus mechanism and instead has the button you see at the 8 o'clock position. That is why only AF-S lens with a built-in autofocus motor, will autofocus on your D5500. By the way, if your camera did have a built-in autofocus motor, you would see what looks like a miniature straight bladed screwdriver blade at this position. This screwdriver blade would turn what looks like a screw head on the lens to drive the lens autofocus. This is why it is called a "screw drive mechanism."

 

[Bob Blaylock]

The item circled is what he is talking about. I don't know what it is for either, but it is on the D5300 also.
View attachment 241500

My D3200 has that too. I think I know what it's for, but I am not certain.

It will most probably the lever for the use of the D type lenses and older(pre G type lenses) that have the aperture ring. When attaching a D lens, you should lock the aperture at the smallest(biggest number) of the lens. f22. align the orange marker to lock the aperture. If the aperture is not set on the smallest, an error message will appear when you attach the lens

That's very close to what I think. I don't have any “D” lenses, I just have the one “G” lens that came with my D3200, and several very old, completely non-electronic lenses.

As you say, with electronic lenses, that are equipped with aperture rings, you're supposed to set the aperture ring to the smallest aperture, or the camera will give an error. I believe the “button” in @cwgrizz's picture is to detect whether the aperture ring is set to its smallest size, and to allow the camera to give an error if it is not.

View attachment 241501
The arrow points to the lever. Just my 2 cents view ☺

That lever is on nearly all F-mount lenses, all the way back to the very first ones in 1959.

Originally, it was to allow open-aperture viewing. Regardless of how the aperture ring was set, the camera could use this lever to force the aperture to be open all the way, while looking through the viewfinder, and then release it to allow the aperture to close to the setting on the aperture ring when the picture is actually being taken.

The AI-S development, I think in the early 1980s, calibrated that lever so that with the aperture ring set to the smallest setting, the camera could use that lever to accurately set the aperture, making shutter-priority auto-exposure possible. That's why, on cameras that use this lever for that purpose, the aperture ring needs to be set to the smallest aperture; otherwise, the camera can only set the aperture as small as where the ring is set. This AI-S development predates lenses with any built-in electronics by over a decade, I believe.

“G” lenses eliminate the aperture ring entirely, and only allow the aperture to be set via this lever.

 

[Fred Kingston]

It's the locking mechanism to lock the lens in position... Press the lens release button on the other side of the mount and you'll see the button retract a bit... When you twist the lens into position on the mount, you'll hear a slight snap as that spring-loaded button snaps into position, locking the lens in position. Pressing the lens release button on the body, retracts that little button, allowing the lens to be un-screwed/from the mount.

 

[480sparky]

The D5200 and D3300 manuals shows it, but don't call it out as to what it's for.

 

[JeGo]

The D5200 and D3300 manuals shows it, but don't call it out as to what it's for.

Well, for where it is located, and from what's been said on this post, I do believe it has something to do with older/different kinds of lenses. Fred said his would move when pressing the lens release button, but mine doesn't move at all unless I press it. It does have a beveled corner though which makes me think that as your twisting a lens on (older/different) it will get pressed down and clicked in to or on to something on the lens.

The D5200 and D3300 manuals shows it, but don't call it out as to what it's for.

Sent from my Nexus 6P using Tapatalk

 

[480sparky]

None of my lenses (current and legacy) have anything on them in that position.

I have E glass, G, D, AI and Pre-AI. Nothing there on any of them. So it's not about old lenses.


Does your lens have anything on it that mates up with it? I know they have a few VII DX lenses, but I don't have any to look at.

 

[JeGo]

None of my lenses (current and legacy) have anything on them in that position.

I have E glass, G, D, AI and Pre-AI. Nothing there on any of them. So it's not about old lenses.


Does your lens have anything on it that mates up with it? I know they have a few VII DX lenses, but I don't have any to look at.

I just have the 2 kit lenses that came with the camera. And like I said, when I twist my lenses on and off I can't see it move at all. I keep calling it a button but it's more like a lever. You would think that with an over 400 page reference manual and a well over 100 page owners manual that Nikon could have at least told what it was.

Sent from my Nexus 6P using Tapatalk

 

[Blacktop]

It's the muffler gasket.:indecisiveness:

 

[480sparky]

Looking at Nikon's manuals for their new 1.4 and 2.0 Version III TC's they have what Nikon is calling a Minimum aperture signal post (EE servo coupling post). It appears to mate up with this myster switch. So maybe it has something to do with using the newer E-class lenses with a teleconverter.

 

[JeGo]

Looking at Nikon's manuals for their new 1.4 and 2.0 Version III TC's they have what Nikon is calling a Minimum aperture signal post (EE servo coupling post). It appears to mate up with this myster switch. So maybe it has something to do with using the newer E-class lenses with a teleconverter.

Hmmm, I'll have to look at that a little closer. It would have to be on the outside of the mounting ring if that's the case.

Sent from my Nexus 6P using Tapatalk

 

[cwgrizz]

Hmmm, I'll have to look at that a little closer. It would have to be on the outside of the mounting ring if that's the case.

Sent from my Nexus 6P using Tapatalk

The TC Convertors do have a tab that moves the little button.

Sent from my iPhone using Tapatalk

 

[JeGo]

The TC Convertors do have a tab that moves the little button.

Sent from my iPhone using Tapatalk

And that does what?

Sent from my Nexus 6P using Tapatalk

 

[480sparky]

It appears to prevent some lenses from using certain TCs. According to Nikon:

Because the maximum aperture coupling ridge and minimum aperture signal post are eliminated with the AF-S TELECONVERTER TC-14E III, “FEE” is displayed on the camera body when these lenses are used, disabling shooting.

Source: Nikon | Imaging Products | AF-S TELECONVERTER TC-14E III

 

[cwgrizz]

And that does what?

Sent from my Nexus 6P using Tapatalk

IT tells the camera that the minimum aperture setting is changed because the TC is connected, I believe.

 

[RobV]

I have a D5300, and a "D" (?) lens NIKKOR 300mm f/4 AF - Nikon Product Database

It seem to be a switch to let the camera know this type of lens is mounted. My D lens has a tab on it to meet this switch.

 

[RobV]

It will most probably the lever for the use of the D type lenses and older(pre G type lenses) that have the aperture ring. When attaching a D lens, you should lock the aperture at the smallest(biggest number) of the lens. f22. align the orange marker to lock the aperture. If the aperture is not set on the smallest, an error message will appear when you attach the lens

The arrow points to the lever. Just my 2 cents view ☺

On this lens, my Green "circle" is the tab that pushes on the mystery switch.

 

[JeGo]

I have a D5300, and a "D" (?) lens NIKKOR 300mm f/4 AF - Nikon Product Database

It seem to be a switch to let the camera know this type of lens is mounted. My D lens has a tab on it to meet this switch.

View attachment 241668

View attachment 241669

Ah ok! Not sure what a "D" lens is but I will look it up. Thanks RobV!

Sent from my Nexus 6P using Tapatalk

 

[480sparky]

Ah ok! Not sure what a "D" lens is but I will look it up. Thanks RobV!

Sent from my Nexus 6P using Tapatalk

A "D lens is the generation before the G. The "D" stands for Distance. It was an improvement over the first round of AF lenses, the D meaning the lens transmitted the focus distance the lens set itself to during AF and told the camera this information via the electrical contacts. The improved proper exposure using speedlights of the day.

 

[Bikerbrent]

It's a thingamajig that interacts with the thingamabob causing the doohickey to send a signal to the whatchamacallit. This allows the camera take a picture. That’s all anyone needs to know about button!

 

[Metal Jacket]

Just checked on my old Sigma 300 F4 and its has a tag which pushes on the button ..D lens ?
Maybe not, there is no button on the D7100 and the same lens works fine on that .....
More tests show that the protrusion on the lens moves with the aperture ring and only aligns when at smallest aperture ( f 22) .That makes the feeler inside the camera open the aperture for focusing.
With the D7100 etc this must be done electronically as there is no lens mount side button.