I don't think anyone can diagnose the problem without seeing the camera
involved, but as a guess I would say your meter is off twoards the
underexposure side.

Compare negatives or slides. Try a roll bracketing the exposures. Check
your shutter speeds. You can do this with a TV set. I don't remember how,
but there are two 312 1/2 lines drawn every 1/50th of a second.

Is the OM2 designed for Mercury batteries? What you describe is almost
exactly the effect of using an alkeline battery in my Nikormat FTn.
(2/3 F stop underexposure). The OM1 used them, the OM1n does not,
was there an OM2n?

Geoff.

FWIW, here's my $0.02

Check the film transport mechanism, and backplate.  Perhaps the film is
not being held flat.

Barring gross mechanical distress, there's not much left for the body to
contribute.  Either the exposure is off slightly, or the focus is out of
whack.  Both are easy to test.  For exposure, simply compare meter
readings of a blank wall, then shoot a few slides and observe the
resulting density.  Focus can be tested by focusing a given lens on the
'good' camera, then transferring the lens to the the other body.  Use
bit of tape, etc., to lock the focus ring.

Exposure correction, if linear, is a simple ASA speed tweak.
If the focus differs, there is probably an adjustable mirror stop
screw/cam to play with.  Adjusting the mirror angle also alters the
focusing-image light path length, allowing you to tune the body's focus
accuracy.

Are you shooting in program mode?  It's possible that one body more
strongly preferrs 'sweet spot' apertures when in full AE.

Other than those possibilities, I got no clue!

-Greg

You may want to join the Olympus mailing group:

http://zuikoholic.com/

and pose the question there.

Others replied about the pressure plate and the meter being off.  One
thing to note, you should use the Silver battery rather than the
alkaline for the OM2 for drain purposes.

Some people throw in the double height lithium cell rather than the dual
SR44 battery and that will throw the meter off.

Are you using the mercury cell in the OM1n, Wein Cell or
are you using an adapter or has the camera been modified to use an
alkaline 625?

JD

There's only a few ways in which the  _body_  can affect the image:

1.  film flatness;

2.  focus accuracy - ie. whether what is in focus on the focusing screen is
exactly the same as what will be focused on the film plane;

(2a. AF accuracy too, though that isn't relevsant in this instance;)

3.  metering accuracy, if you rely on the meter;

4.  metering pattern, if one meter pattern suits your type of subjects
better than another, and you rely on the meter;

5.  programme line, if you use programmed AE;

6.  camera produced vibration - ie. how well things like the mirror and the
movement of the first shutter curtain are damped;

7.  camera flare - ie. how much or how little non-image-forming light is
scattered about in the mirror box;

and an unlikely / unusual one -

8.  any misalignment/damage that affects the image - this is basically if
the plane of the lens mount is out of parallel with the film plane, not a
common thing as you can imagine.

I think the first five of these have all been mentioned already in this
thread, and I'd say metering sounds the most likely culprit for the symptoms
you describe.  Try taking shots on both bodies, using the metered exposure
from one body on the other one, and then vice versa (keep notes).  This will
tell you if it is the metering that is the problem.  Indeed, just seeing if
they read the same exposure when each is pointed at the same scene will be a
very strong clue.

Next most likely cause of the particular symptoms you describe is camera
flare - though I don't know whether the flocking of the OM1n and OM2 differ.

Peter

Check out:

http://www.mir.com.my/rb/photography/hardwares/classics/
    olympusom1n2/om2/om2manual/index.htm

(put the url back together before using).

It discusses the battery issues with the OM2.

Geoff.