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Thread: ISO Question

  1. #1

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    ISO Question

    Scenario:
    After metering a scene based on ISO 100 film and placing the shadows on Zone 3, I then expose the image.
    After making the exposure, I realise that the film used was actually 400 ISO film.

    Question:
    Would the shadows now be on Zone 5 ?

  2. #2

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    Re: ISO Question

    Quote Originally Posted by ic-racer View Post
    You under exposed two stops, so now those shadows are going to be on zone one. So, if those are very dark shadows, you negative might come out Ok. If you had put the shadows on zone one in the first place, they would probably be no density on the negative in those areas.
    Thank you

  3. #3
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    Re: ISO Question

    Quote Originally Posted by ic-racer View Post
    You under exposed two stops...
    He metered and exposed for a slow film, but it turned out to be a fast film. The shadows should be amply exposed.

  4. #4

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    Re: ISO Question

    If you metered for ISO 100 and shot on ISO 400 film you OVEREXPOSED by two stops. I take it this is black and white, right? If so, you're probably ok. Who knows, you might have exposed like Edward Weston.

  5. #5

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    Re: ISO Question

    Yep, you overexposed two stops and your Zone III placement is now Zone V. Don't worry, most modern black-and-white (and even color negative) films will hold highlight detail with even more than two-stops overexposure. Just develop normally and print longer. You may be surprised at the great shadow detail you have.

    Doremus

  6. #6
    Resident Heretic Bruce Watson's Avatar
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    Re: ISO Question

    Quote Originally Posted by IanBarber View Post
    Scenario:
    After metering a scene based on ISO 100 film and placing the shadows on Zone 3, I then expose the image. After making the exposure, I realise that the film used was actually 400 ISO film.

    Question:
    Would the shadows now be on Zone 5?
    They would be, yes. Two stops over exposure. You could try developing one stop less. You could go two stops less if you have sufficient development time available. Else you risk streaking.

    But IMHE developing one stop less is almost always sufficient. You'll just get better shadow detail because of the over exposure, and you'll have a little more graininess because of the over density on the film in the highlights. No biggie.

    Bruce Watson

  7. #7
    ic-racer's Avatar
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    Re: ISO Question

    Quote Originally Posted by Oren Grad View Post
    He metered and exposed for a slow film, but it turned out to be a fast film. The shadows should be amply exposed.
    Yes, thank you, I misread. This is more like it. With Large Format film you will likely still be on the plateau.

    Click image for larger version. 

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