[guillaumedavidphd]

Hey there!
I'm experiencing some problems with my 645 NII and 45-85mm f/4.5 lens and thought someone on this forum might know of a solution.

In certain cases the pictures are severely underexposed, to the point that they are not salvageable. The camera has a feature that lets you print the shutter speed and aperture on every picture, and I've been using this to diagnose it. Based on this, the meter in the camera seems to work as the shutter speed and aperture are spot on. However some pictures end up underexposed. A striking example of this is attached to this message: I took two photos successively in the same lighting conditions, and the meter measured 13.5 EV in both cases, but one of the pictures is underexposed beyond salvation while the other is perfect. I suspect it could be a problem with the shutter itself, or the aperture of the lens. I want to point out that the problem seems to happen in P-mode, and not in aperture priority.

Is anyone familiar with this and could point me in the right direction to fix the camera?
Thanks!
-Guillaume

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[Smolk]

It would seem that 1/350 s + F5.6 is roughly equivalent to 1/125s + F9.5, so the metering doesn't differ (although I'm at a loss why it would choose such different apertures/speed combinations).
I'm not sure whether you can check the shutter without film in the camera - perhaps without the film insert, with the special back?

[guillaumedavidphd]

It would seem that 1/350 s + F5.6 is roughly equivalent to 1/125s + F9.5, so the metering doesn't differ (although I'm at a loss why it would choose such different apertures/speed combinations).
I'm not sure whether you can check the shutter without film in the camera - perhaps without the film insert, with the special back?

Thanks for your comment! The aperture/speed combinations are different because in one case the camera was in auto mode (P) and in the other case it was in aperture priority (Av) and I manually dialed in f/5.6. I'm not aware of this special back you're talking about, could you elaborate?

[tuco]

f11 @ 1/125th ( or equivalent) would be a Sunny 16 exposure for higher latitudes or early spring/late fall for 100 film. And it looks pretty sunny out to me.

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Last edited by tuco; 12-31-2021 at 11:42 AM. Reason: Oops

[rpjallan]

The only time I ever remember seeing a problem similar to this was on my dad's LX and it turned out to be a battery/power problem. Unfortunately I can't remember the exact details but it might give you somewhere to start looking.

[Smolk]

If memory serves me well, there is a flat black cap that you can place instead of the film insert and that allows you to check the functions of the camera. It's been some time since I owned the camera though.

[guillaumedavidphd]

So I did some more digging, and it looks like the problem comes from the aperture. Whatever the meter measures, the camera always closes down to f/32 in P mode, which is the smallest aperture the lens supports. Of course, in aperture priority mode this doesn't happen since the aperture is physically dialed in by the user. Now the question is: is it coming from the body, or the lens? Unfortunately I do not have another lens to test the camera with... Any suggestions of things I could try to figure that out?

[guillaumedavidphd]

It seems the culprit is the aperture lever in the camera body (see picture attached). I took a short video of the problem (here: Shared album - Guillaume David - Google Photos) but in a nutshell, the lever is sticking and not moving freely. In aperture priority this sometimes causes the camera to think that the aperture selected with the ring is between 2 physical aperture, and in P mode it causes the camera to think the aperture selected is f/32. Any suggestions as to how to fix this? Alternatively, anyone could recommend a qualified repair person in the US?