PC-Nikkor 3,5/28 for OM - Problem with metering

[joachim_hildebrand]

I just bought a PC-Nikkor customized for OM and face the following Problem on a

OM 4Ti: The meter shows way to long times (with no shifting!) which would cause

overexposing of maybe 6 - 7 EV. There is no Problem with my original OM Shift

2,8/35. I have an OM to EOS adaptor for my EOS 5D on which metering with both

lenses works fine. What could be the problem with the 28 PC-Nikkor on the OM 4Ti?

 

Thanks for Your help, Joachim

[richard_s.]

Maybe the lever for seting the aperture is missing or bent on the adapted lens.

 

Check any T2 adapter for OM to see what im talking about.

[basscheffers]

Does that Nikor actualy signal its chosen aperture back to the body in the same way an OM-

lens does? (with a lever)

 

I have admit, I have no idea how Nikkor lenses work in that regard, so just a thought...

[neild]

It must be the mechanical lever for the aperture setting (or an absence of one). The exposure is fine on your 5D because you are using stop-down metering. Can you not also use stop-down metering with the Nikkor when on the OM-4Ti? I know the Zuiko has a button which toggles between stop-down and wide-open - perhaps the Nikkor has a similar feature?

[richard_cochran]

I have no idea how the OM side of things works, but I'll point out that the PC-Nikkor 28mm f/3.5 lens is a preset lens with no auto diaphragm and no meter coupling. In order to accomodate the shifting for perspective control in those days before electronic coupling, the engineers at Nikon decided to entirely forgo all meter coupling and auto diaphragm linkage. You open the diaphragm up manually to focus, then close the diaphragm manually to meter and take the picture.

<p>

A side note: most in-camera meters are only accurate with the lens centered, so if you're using the shift feature, you usually must shift after metering and before taking the picture. But Joachim says he's seeing the problem while the lens is still centered, so this isn't his problem.

<p>

If the OM somehow has meter coupling that is confused and thinks the lens is currently wide open but will stop down 6-7 stops for the exposure, that would be consistent with the symptom Joachim is reporting. I'll leave it to the OM experts here to explain how that might happen, or come up with alternate theories.

[joachim_hildebrand]

UPDATE

 

I inspected the bayonett of other OM lenses. On their outer side they have two "notches". One looks, as it could be turned/removed with a screwdriver. I suspect this one is for stopping the movement when mounting the lens. The other one is barly visible on first sight and rectangular. Both are in the same place on different lenses with different maximum apertures. Otherwise I would think one of these notches tells the camera the widest aperture. Everything on the Nikkor looks the same. But why does it behave different? Maybe one or both notches on the Nikkor are slightly bent or to short. This would mean that even for an only in stop down mode working lens you need a notch. Seems a bit weird as other systems don?t need any notsches for stop down lenses.

 

The OM shift does not tell the camera the set aperture and only works in stop down mode. The linkage lever which intrudes in the camera and which the other lenses have is missing. The button which quickly opens the aperture is only for framing and focusing an not for metering. The same thing does a ring on the PC-Nikkor (aperture preset).

 

Now it gets really weird: I mounted the PC-Nikkor on an OM 2 Body and basically the same happend BUT NOW even when the meter shows a shutter peed of a second, after pressing the release button the shutter speed was much shorter maybe 1/60 or 1/125 sec. As I pointed the lens in an darker area of my room, shutter speeds got longer. It seemed that the OM 2 used the correct speed even when showing the wrong one in the finder. I doublechecked this with the OM 4 Ti but the OM 4 used the shown speeds. Now tell me what is happening here.

[neild]

If the OM-2 is on auto mode it will read the exposure during the photo and adjust accordingly. The OM-4 should also do this, so maybe the OM-4 was in manual mode when you had your problems? (or else the OM-4 needs a service!).