mamiya 7 underexposing problem

Discussion in 'Medium Format' started by danny_liao, Aug 10, 2009.

  1. I took it out today and noticed that it's underexposing by several stops. Everything is set correctly...iso320, AEL, aperture, etc. At f4 with ael metering, it's showing me 1/8 of a sec on a bright sunny day in so.cal at noon. Does anyone know what might be the cause? Thanks in advance.
     
  2. Danny,
    If you are getting a reading of 1/8 second on a sunny day, it would be overexposing by several stops(actually quite a number of stops-sunny 16 rule=1/320 second at f16). Try taking the lens off and reseating the lens. Also you could clean the lens contacts with an eraser(carefully).
    Randy
     
  3. Danny,
    If you are getting a reading of 1/8 second on a sunny day, it would be overexposing by several stops(actually quite a number of stops-sunny 16 rule=1/320 second at f16). Try taking the lens off and reseating the lens. Also you could clean the lens contacts with an eraser(carefully).
    Randy
     
  4. Randy,
    Thanks for pointing that out. I meant to say, OVER EXPOSING! I just cleaned the contacts and the problem is still there.
     
  5. Is your lens hood properly attached and not obstructing the field of view?
    Though admittedly, if I'm calculating correctly, nearly 9 stops of EV error - something is seriously wrong there. Even at f/22, assuming your lens didn't report aperture correctly, that's still only about 5 stops.
    My supposition is that something is quite wrong with your camera's meter itself, or whatever circuitry ties back to the display.
     
  6. Hi Danny,
    Try replacing the battery and see if that gives more accurate readings. I've had cameras where the battery was on the verge of going and this lead to strange readings.
    If not... you may have to send it in for an adjustment.
    Cheers
     
  7. Thank you all for your help. I replaced the battery and still the problem exist. Yes, I think there is something wrong with the metering. Now, can anyone suggest a good reliable repair shop in Los Angeles?
    Thanks
     
  8. Have you tested exposure with a different lens? Did the new lense give you the same over exposure reading? If the answer is no, then the problem might be with the lens.
    BTW. What reading did you get when you manually meter?
     
  9. the meter is a spot meter and it's not necessarily centered. someone else here suggested you can find the spot by experimenting in a darkened room with a candle. the spot is near the center on some mamiya 7s and sometimes down and to the right. you'll probably discover the spot was in a shadowy part of your subject, when you got the incorrect reading.
     
  10. david_henderson

    david_henderson www.photography001.com

    I'm afraid the magnitude of this error indicates a probable malfunction rather that user error or the meter being not centred. And as it doesn't meter ttl the fact that the unrealistically long exposure is showing as a meter reading seems to indicate a problem with the meter not a lens.
    The only possibility I can think of is that you have somehow obscured the meter window when taking the reading and exposing. Pretty unlikely I'd have thought.
    Incidentally the meter is not a spot meter. Not being ttl it measures exactly the same area no matter what lens you have fitted, and is centre weighted not a pure spot. Whilst it takes measurements only from the central area of the field of view of a wide angle lens, with the 150 fitted it takes a small part of its reading from outside the frame altogether.
     
  11. You might try Manny's Camera repair, on Sunset Blvd, in Los Angeles. Just north of Downtown. He's a very honest guy, and really enjoys older cameras.

    If you are very clear with the symptoms, and tell him beforehand, he will be honest in whether he thinks he can repair it or not.
    Now, can anyone suggest a good reliable repair shop in Los Angeles?​
     
  12. david -- thanks for correcting my assumptions and lack of clarity.
    i haven't had my 7 for very long, but i have noticed something very similar to what danny describes. a couple times i was setting up a shot and thinking to myself, OK, this will probably be good at about 1/250 and f11 -- and it move the dial to 250 and lens to between 8 and 11, very lightly hold down the shutter release button, peer through the finder and it is flashing 60!! and i think, man, that can't be right! so i pan around a bit until i get a more reasonable suggestion from the meter, then adjust it manually. and end up taking the shot at 1/250 and f8. and it all works out fine.
    bottom line -- healthy skepticism is good, and don't over-rely on a built-in meter.
     

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