Just bought an FM, Metering Issue

[zebulus]

So I just got a Nikon FM from KEH. There seems to be an issue with it, but im not sure if its me or the camera.

Every lens I mount on it stops down when I change the aperture. I have the AI ring set properly, and the main lens im using on it is the Tokina 28-85 AT-X AI, but I took it to a camera shop over the weekend and tried an 85 1.4 and a 50mm 1.8 series E on it and it did the same thing, would stop down when I moved the aperture ring, even though the camera was set to auto indexing.

Anyone familiar with this issue, is it the camera?

 

[Nick Merritt]

It does sound like the camera, since that's the consistent factor here. Just so I'm clear -- the little tab on the aperture coupling ring (that enables the use of non-AI lenses in stop-down mode) is flipped up and out of the way, correct? You probably said this a couple of times in your note, but I wanted to be sure I understood.

 

[Ian C]

I believe there might be something wrong with the body. It sounds like the depth of field preview mechanism is stuck in the engaged position—at least internally. This is operated by the lever to the left of the lens mount as you face it. The lever rotates forward & down to stop down the aperture. It’s spring loaded and should return to the normal viewing position as soon as you release it.

However—there might be nothing wrong if the meter coupling tab is in the “raised” position. Simply lower it to engage the meter coupling ridge of an AI type lens. I think it needs to be in the lower position to hold the aperture open for viewing with an AI lens.

See page 26 “Stop down exposure measurement” here.

http://www.cameramanuals.org/nikon_pdf/nikon_fm.pdf

 

[zebulus]

It does sound like the camera, since that's the consistent factor here. Just so I'm clear -- the little tab on the aperture coupling ring (that enables the use of non-AI lenses in stop-down mode) is flipped up and out of the way, correct? You probably said this a couple of times in your note, but I wanted to be sure I understood.

No its in the down position because im using an AI lens. My understanding was I would only flip it up and out of the way if I were using a non-AI lens, correct?

@Ian C, that's what I thought too, but whats wierd is with the lens off, when I depress the DOF preview lever, the little pin moves down, like it is supposed to. But I know its not my lens because I have an N2020 that it works fine on.

Should I call KEH? I just bought the thing so its covered by their 6 month warranty.

 

[Ian C]

Yes, if the meter coupling tab is in the down position and you’re using an AI lens and the lens stays stopped down to the aperture position set on the lens’s preset ring, then the camera needs to be exchanged for one the works properly.

The nice thing about buying from KEH is that the company will replace or refund the price of something that fails within the first 6 months after the sale. I've found it to be a good place to buy used equipment.

 

[zebulus]

That's what I needed to know! Thank you for your help guys.

 

[Aja B]

No its in the down position because im using an AI lens. My understanding was I would only flip it up and out of the way if I were using a non-AI lens, correct?

That's correct.

The aperture lever in your FM may be bent. It appears to be stopping down, as you have visually verified, but it is not engaging the aperture lever on the lens. The aperture most certainly should not be stopping down when you rotate the ap ring. The FM needs to be repaired, plain and simple.