DX Coding, Exposure tolerance

Discussion in '35mm Cameras and Accessories' started by abruzzi, Sep 16, 2018.

  1. abruzzi

    abruzzi Member

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    I was looking at the DX coding chart today, and I thought its interesting what the second row is for. It records the number of exposures on the roll, and the”exposure tolerance.” I pulled two rolls of Fuji I had—Superia X-TRA 400 and Velvia 50. The C41 film has the code for +3/-1 and the slide film has the code for +/-(1/2), which seems about right. Which of course begs the question, do any cameras actually read the exposure tolerance codes, and if so, what do they do with it? (I looked at the only DX enabled camera I have, the Nikon F4, and it only has a single row of sensors.)
     
  2. AgX

    AgX Member

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    I assume that tolerance information only makes sense with complex metering systems.
     
  3. EdoNork

    EdoNork Member

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    Maybe used by the Minilabs equipment?
     
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    abruzzi

    abruzzi Member

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    yeah, I was just curious if and how the information was used. I was thinking that a matrix system could adjust by in inferring dynamic range, though that not really what the data indicates.
     
  5. darkroommike

    darkroommike Subscriber

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    Having worked in a mini-lab I'll say no. Unlike APS, with 35mm, the cartridge is discarded before the roll is processed or printed, and not reattached after processing.
     
  6. MattKing

    MattKing Subscriber
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    It would tell the camera that slide film is present.
     
  7. darkroommike

    darkroommike Subscriber

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    Yeah but only if your camera supports the second row of DX pins. I just checked the manual on the F6 and it doesn't mention anything about that DX feature. Does anyone have a camera example that has two rows of DX pins in the body?
     
  8. darkroommike

    darkroommike Subscriber

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    I am going to quote myself, the DX cartridge code was not used in mini-labs, and very few mini-lab printing machines supported the DX edge code. In any case that's ancient history.
     
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    abruzzi

    abruzzi Member

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    The other thought I had was maybe for later consumer cameras that implemented “exposure compensation” with buttons and an LCD, they might have read the code, and limited how much exposure compensation you could dial in based on the DX information.

    Or maybe it was never actually implemented. I doubt I’ll ever see a camera that uses it, I’m mostly just curious if and how it was used.
     
  10. pentaxuser

    pentaxuser Subscriber

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    It is a good question. There has to have been a reason for it but for what that could be used and by what means?

    pentaxuser
     
  11. Agulliver

    Agulliver Member
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    In theory a camera or lab could use the information....but I'm unsure if it was ever widely implemented. Possibly something that the DX code designers intended but which was rarely used in real life.
     
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