m42 metering adjustment

Discussion in '35mm Cameras and Accessories' started by truls, May 4, 2012.

  1. truls

    truls Member

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    It is about 25 years since I did some hobby photography...
    Some of my knowledge is forgotten. Now I have bought a cheap APS film SLR camera (Canon IX7) and two m42 lenses (Helios 44, Industar 50-2), mounted on a EOS to m42 with metering capabilities.. The pictures turns out very sharp, but I have problem with consistent underexposed pictures. Is there a camera or m42 lens problem, or do I have to adjust ASA settings manually? Using the "sunny 16" rule gives proper pictures, but metering gives underexposure.

    Anyone?
     
  2. steven_e007

    steven_e007 Member

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    I don't know the IX7 at all... but it must have through the lens metering so that takes care of whatever funnies might belong to the lens.

    Are you setting the film speed manually or relying on the DX coding? Either way... if you get good exposures with 'Sunny 16' but not with the meter... it certainly sounds like a metering problem. If you point the camera at a mid grey card in bright sun at mid day - what shutter speed does it advocate (or select) for f16 at 100 ISO?

    If the meter is reading incorrectly, but is still consistent and proportional to the light intensity (i.e: it is just a stop or two out) then you can select a different ISO value and cope with it. This is very common on old selenium cell meters, less so on relatively modern cameras. If it is just reading nonsense - maybe you need to pick up a cheap external meter?
     
  3. truls

    truls Member

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    I borrowed my wife's camera, and cloudy conditions showed 125/f.8 at ISO 100. My camera proposed 1/500 at f.8 at ISO 100 (stop down metering). Maybe it is a simple solution setting ISO manually 2 stops lower. The Canon IX7 is like other Canon EOS, same lens mount etc, but APS film format. As I was suprised by the error in metering I thought maybe the m42 lenses are spesial and there were some spesial settings some of You pros knew about. Thanks for your time!
     
  4. steven_e007

    steven_e007 Member

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    No - a lens is a lens... but does the camera expect to read the aperture settings from the lens? As I said, I don't know the IX7 at all, but being a modern (ish) camera maybe it expects to read the aperture settings electronically from the lens? If the lens doesn't have the contacts (which it almost certainly won't have) then maybe the camera thinks the lens is at full aperture at the point of exposing the film, when reality it is closing down to whatever you've selected, hence under exposing.

    Have you selected the manual setting on the lens and actually closed the aperture down whilst metering? Some lenses have a button you can press to do this, others you have to select manual and stopped the lens down (and some can't do it at all...).

    Could this be the problem?
     
  5. truls

    truls Member

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    Hello,
    The EOS->m42 adapter is reading the lens stopped down, and have contacts for communication between camera/lens (only aperture priority/manual). I have to meter by setting an aperture, then the camera should select the correct shutter. It works, but the selected shutter is too fast (2 stops). It don't work on automatic, the camera can't control the aperture. I will try to shoot a 12-roll test film (ISO 100) at ISO 25. Outdoor the sunny 16 is easy to use, but inside the guessing is worse.
     
  6. Alan Johnson

    Alan Johnson Subscriber

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    I know the procedure for the EOS Rebel S11,perhaps your camera may work like this:
    (1) Stop down the lens to the aperture required (of course this cannot be done with an auto only M42 lens).
    (2) Set the camera to aperture priority but do not set this to the required aperture,rather set it as indicated here:
    http://photonotes.org/articles/eos-manual-lenses/