Olympus OM-2: advice / help sought

[David Lyga]

Recently, I bought a 'used' OM-2 (the original, not the 'n') and it is in near mint condition with 1.4/50. The meter works flawlessly in both manual and auto. In manual, the shutter speeds are accurately timed.

My problem is this: in auto the meter, as I said, works flawlessly but the timing of the shutter in auto is about 1.5 to 2 steps too slow. For example, if the meter says 1/30 sec the real timing is 1/8. If the meter says 1/8 sec the real timing is 1/2 sec. As I stated before, in manual there is not this problem.

Is there a different circuit for the meter needle vs the timing chip? Is this problem common? This is easily 'got around' by knowing this in advance but in auto, negatives are over-exposed if one is not cognizant of correcting this. I have not yet checked the faster speeds and do not know if, for example, when the meter says 1/1000 the timing is really 1/250, so this problem just might be with only slower speeds. I would be interested in feedback. Thank you. - David Lyga.

 

[chriscrawfordphoto]

The meter on autoexposure mode is only accurate if there is film in the camera. If you shoot the camera empty, the shutter stays open too long. This is because the OM-2 (and the 2n, 2s, 4, and 4T) all read directly off the film in auto mode. No film in the camera means the meter cell sees the black pressure plate and thinks the light is dim!

 

[RH Designs]

When new the OM-2 and other auto OMs came with a little piece of card you put in the film gate to mimic the presence of film if you want to check the auto speeds. Otherwise as Chris says auto speeds will seem to be too slow. In the OM-2(n) the OTF auto metering uses a completely separate circuit from the v/f meter. The acid test is to run some film through the camera of course!

 

[David Lyga]

Thank you both for 1) reminding me that I am not infallible and 2) helping me to re-invent the wheel.

I would have never have come to that conclusion because it was so obvious. This forum serves its purpose with folks like yourselves. - David Lyga.

 

[mr rusty]

Hmmm. I think only a partial answer, because above 1/60th the metering is not off the film, but off the white dots on the shutter curtain, so the faster speeds won't be affected by this theory. more here http://www.mir.com.my/rb/photography/hardwares/classics/olympusom1n2/om2/htmls/index2.htm

Don't know what country you are in but if you need them there are good olympus techs in both UK & US. John Hermanson is the OM guru in the US http://www.zuiko.com/ and I recommend Mike Spencer at http://www.camerarepairs-r-us.co.uk/ in the UK - he's done both my OM1 and OM2.

 

[MattKing]

Hmmm. I think only a partial answer, because above 1/60th the metering is not off the film, but off the white dots on the shutter curtain, so the faster speeds won't be affected by this theory. more here http://www.mir.com.my/rb/photography/hardwares/classics/olympusom1n2/om2/htmls/index2.htm

Even if the indicated speed is faster than 1/60, at least part of the metering is off the pressure plate, because the shutter does open, and the film plane is at least partly exposed, so the different reflectivity does matter.

And of course the lack of film at the film plane will tend to slow down the shutter speed (delay the start of the second, closing curtain).

 

[David Lyga]

And the pressure plate is black, necessitating the meter to force more exposure. My original concern was with slow speeds which I aurally tested without film. I did, after reading the replies, place a medium gray piece of paper on the film gate and aurally tested again. Perfection. - David Lyga.

 

[mr rusty]

Hi David. Great thread! I learned something more about how this great camera works. If you haven't already seen it, there is good technical description about all the electronics behind this in the service guide found here http://olympus.dementia.org/Hardware/

 

[John Hermanson]

If lens is not mounted (and no test card loaded), then the shutter speed indicated in the vf is meaningless. f stop coupling ring in body is at the (at least) f32 position, while amount of light entering chamber is like f 1.0 due to no lens. Even a medium toned piece of "post it" at the film plane is good for testing otf shutter speed. Cross over from reading off the film to reading the first curtain is between 1/30 and 1/60. John