Olympus OM-4 - Electrical issues

Discussion in 'Olympus' started by oliver_mills, Apr 2, 2019.

  1. Hello.
    I recently bought an Olympus OM4 with a 50mm f/1.4 lens from an antiques shop. It is in very good physical condition and seems to work well mechanically, but there seem to be several electrical issues. The main issue is the shutter speed in Auto mode, which is significantly slower than the correct meter reading indicated on the LCD display. I have tried testing it to find a fixed pattern (a common error in the shutter speed - e.g. +2 stops) but it seems to vary from about +1 stop to +3 stops longer than the metered speed. Strangely, it is not a problem in spot metering mode - the shutter speed here is correct to the meter. The manual mode, of course, works fine.

    Today was the first time I noticed that the spot metering system was becoming temperamental. As I was testing the shutter speed issue, the spot metering suddenly stopped working - all of the associated buttons and memory levers did not respond. I later realised that the spot metering would only work when the lens switch (a conical button on the lens mount, below the red registration dot) was depressed by the attached lens, and this switch was temperamental. In theory, whenever the lens was removed, the camera would beep and the spot metering would be disabled. Unfortunately, the switch would often randomly disengage if the lens was touched or twisted, causing an erratic barrage of beeping and erroneously disabling the spot metering. Depressing the button with a fingernail (further in than the lens would) seems to create a more solid electrical connection, so I might find a means of fixing the button permanently.

    This video demonstrates the issue with the shutter speed.
     
  2. Hi,
    Maybe if you load a (spoilt) film, you may find that the shutter speed will coincide with the meter reading: the SPD cells looks at the film. If there is no film inside the camera, it will see the black pressure plate, and that will change the shutter speed considerably (it's a "live"system), compared to the reading before you release the shutter.
    As for the switch, maybe a tiny dop of lighterfluid will remove the grime.

    Cheers,
    Jan
     
  3. Correct the meter reading in the viewfinder is kind of for your eye only. A separate metering system is used to control exposure time and this system rely on the reflection off the film.
     
  4. Fantastic, it has worked! I did not know that the camera relied on the film surface to obtain a meter reading, I previously tested the shutter without film, as I did for my other cameras. This is my first film SLR camera with a proper metering system, so I am quite new to this type of camera, but I have been very pleased with its operation so far.
    Thank you very much for your help!
     
  5. Vincent Peri

    Vincent Peri Metairie, LA

    You might want this:

    http://www.cameramanuals.org/olympus_pdf/olympus_om-4t-bw.pdf

    It's a manual for an OM4T (titanium), but I don't know why it wouldn't apply to a regular OM4.

    If you find the manual useful, please send the website owner $3 so he can continue supplying manuals.
     
  6. In spot metering the camera uses the metering to set the shutter speed so it doesn't matter if you have film in the camera or not. When not in spot metering mode it meter off the film plane. This feature is especially useful for extra long exposure when the light can change during the exposure and the camera will automatically adjust for this. I personally do not like this behavior or the use of one metering system for viewfinder readout and another for the actual exposure but our Photonet member Les Sarile (I think I spell his name wrong, My apology to Les) loves it althoug his favorite camera is the Pentax LX and not the OM-4.
     
  7. That is useful to know and seems to align with what I was experiencing. I am surprised that the metering can potentially adjust in real-time during exposure, but I suppose this camera has one of the most advanced metering systems of the time. I have been using an Olympus OM-1N for the last few years, which is excellent to use, but there is something about the OM-4 which makes it feel even more solidly built - perhaps it is the matte black paint and increased weight. £45 seems to have been a very good price from the antiques shop for this OM-4, a Zuiko 50mm f/1.4, and a Recordata 4 back, all in excellent condition.

    Thank you for clarifying how the meter works, I now know that the camera is essentially perfect in operation except for the well-known battery drain issues.
     
  8. You can test this behavior by putting a piece of film at the film gate (so you don't waste film testing). Release the shutter in a rather dark place and see how long the exposure is. The next shot do the same but as soon as you release the shutter shine a light into the lens and you will see the shutter closes much sooner than the first shot.
     

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