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I have a Nikon 100mm f/2.8 Series E mounted on my D300. When I set the aperture on 2.8 on the lens, it is seen as 1.8 on the D300. At its maximum, when set at f/22 on the lens, it is seen at f/16 on the D300. At any aperture, the D300 sees the lens at 1 stop difference from real.
What can cause that and how may I force the D300 to properly recognize the good aperture set on the lens ?
Edit 1 : There is no exposure compensation set
Edit 2 : Some pics of the mount from each side
For that kind of lenses (all without CPU, mainly all manual focus, except the AI-P ones) you have to "declare" them in the SETUP MENU and then Non-CPU lens data if you intend to use the body's metering and selection of aperture.
That way your D300 will know you are at the right aperture.
Do not forget to set the seeting f7 - Aperture setting to Aperture ring as well if you want to use the original aperture ring from the lens.
By doing this you also benefit of the Matrix metering (Color but not 3D) for this old lens.
There are 2 mechanical contacts on the bayonet ring, little metal tabs. One can move, the other is fixed in place. In your top picture you can see the spring that keeps the second in position, and in all of them some wear on the contacts is visible (this is normal, nothing to worry about). The spring loaded one is triggered by the camera to force the aperture open and closed as needed during exposure. The other AFAIK is for calibration/alignment purposes.
There's a third tab on the aperture ring, which on your lens looks suspiciously small, maybe too small to make proper contact with the matching tab on the camera body. this is the tab that communicates the set aperture value to the camera. If it doesn't link up with the matching tab on the camera body, the camera can never know what value is desired.
Mind that this does look consistent with other E series Nikon lenses, so it's not broken :)
And according to this site you're out of luck as the E series does not have meter linkage prongs. More information on the E series here (mind there is another Nikon E series, which are early professional DSLRs, we're talking about the old E series lenses of course).
In short, looks like you're going to have to go full manual using this lens (whichever focal length it is, there is no 200mm Nikon E prime, the longest is 135mm).
I don't know Nikor lenses that well and can't find any documentation on a 200mm f2.8 Series E prime, but if it uses a pin to physically communicate the aperture setting instead of an electronic signal, then it sounds like the depth it is depressing is out of calibration. If it is pushing too little or too far, then it would misregister on the camera body. You could adjust it by either adding or subtracting material from the pin.
Note, this only applies if the lens uses a physical pin to indicate aperture to the camera body. You should be able to verify by looking at the lens mount as you adjust the aperture. It should also let you determine which direction it is off by.
Update: I found this blog posting with a lot of great info and pictures of how the various aperture settings on Nikor lenses have been communicated with the camera body over the years.
