Konica AutoReflex T2 - Color Sensitive Meter Wierdness

Discussion in 'Camera Building, Repairs & Modification' started by Lamar, May 12, 2011.

  1. Lamar

    Lamar Member

    Messages:
    361
    Joined:
    Dec 22, 2008
    Location:
    Georgia, USA
    Shooter:
    35mm
    I have an AutoReflex T2. My father purchased it new in 1970 or so and I use it now. I have been fighting a meter problem and think I have found that the meter is oversensitive to the color green. I know it shouldn’t be. I have had the meter calibrated and a full overhaul of the camera at KEH to try to correct the problem but it still persists. Before calibration the camera would underexpose by one stop with 1.5 volt silver oxides or alkalines. Since calibration, if I use 1.4 volt zinc – air batteries the camera consistently over-exposes by one stop. If I use the 1.5 volt batteries it exposes correctly unless there is a significant amount of green in the viewfinder. (Trees, Grass, etc.) at which point it will underexpose by about a stop. Using 1.5 volt batteries the camera passes the sunny 16 test on blue sky and matches the readings on my Nikon FE2, F100, and both F4’s. It also matches pointing at red brick walls, concrete drives, and black asphalt. But when I point it at a green patch of grass or leaves it will underexpose by one stop. (I make sure there is a uniform color and even light distribution in the viewfinder and all meters are set to center-weighted average). Using 1.4 volt zinc-air’s the meter consistently overexposes by one stop in the sunny 16 test and compared against all the other cameras. Testing was done with no filters on the lenses. KEH says the meters are not color sensitive and there is no way to calibrate it to respond differently for specific colors. Has anyone else seen this or does anyone have any suggestions.
     
  2. Ron G

    Ron G Member

    Messages:
    38
    Joined:
    Jul 15, 2009
    Shooter:
    35mm
    With the price of those T2s being what they are these days I would buy two or three to compare with.You may end up with a couple of lenses that you don't have now if you watch your bidding.Ron G
     
  3. Diapositivo

    Diapositivo Subscriber

    Messages:
    2,260
    Joined:
    Nov 1, 2009
    Location:
    Rome, Italy
    Shooter:
    35mm
    My gut feeling says that the camera is not oversensitive to green but to infrared.

    You might maybe compare with something green and something non-green of the same material and temperature, e.g. two plastic objects.

    You could also compare two objects one cold, one hot (water bowl heated at microwave, let's say, near same water bowl of cold water, in identical light conditions).

    I don't know about this specific camera. CdS Light meters have a known shift toward red and infrared, not easily correctable by the makers. "Blue" silicon cells have a blue filter in front of them to help reach a more linear response, and they are supposed to be more linear than CdS.

    CdS is not so reliable: memory effect, slowness in adjusting and non-linearity of colour response make them, IMHO, the worst light meters on Earth. As ever, if you use negative film most everything is good enough, if you use slide film no attention in determining exposure is excessive.
     
  4. Lamar

    Lamar Member

    Messages:
    361
    Joined:
    Dec 22, 2008
    Location:
    Georgia, USA
    Shooter:
    35mm
    Hmm, never thought of that. I honestly don't know much about how the materials used for light meters work. You're absoloutely right about the slide film. The first roll of E6 I ran through it is when I first noticed the problem, never realy noticed it with negative film. I'll stick with negative film for this camara. I can shoot slides with my Nikons.
     
  5. MattKing

    MattKing Subscriber

    Messages:
    16,811
    Joined:
    Apr 24, 2005
    Location:
    Delta, BC, Canada
    Shooter:
    Multi Format
    Green foliage reflects a lot of infra-red light, so I agree with Diapositivo.

    I'd check your Konica's meter against the other meters using something painted with green paint. I would bet that the meters will read the same.

    If you haven't experimented with it before, you might want to try shooting some of the IR sensitive film. At least you have a meter suited to that purpose :smile:.