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Thread: Exposure factor of B&W PL?

  1. #1

    Join Date
    Jan 2001
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    Exposure factor of B&W PL?

    Recently I got a B&W PL, but I could not find anything about exposure factor on the box, and they didn't print it on the ring. Anybody can get me tips? Thank you.

  2. #2
    Shadow Catcher
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    Exposure factor of B&W PL?

    What is a B&W PL? Pat

  3. #3
    Robert A. Zeichner's Avatar
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    Feb 1999
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    Exposure factor of B&W PL?

    I'm going to guess this is a polarizer. If so, you might start at 1-2/ 3 to 2 stops. I suppose you could also meter through it at a flat target like a grey card.

  4. #4

    Exposure factor of B&W PL?

    I expect it's a B&W manufactured linear polariser you're referring to.I'd go with the above, 1.5 to 2 stops, but it really depends on how much polarised light is reflecting from the subject. Stick it over your meter or take a TTL reading.

  5. #5

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    Exposure factor of B&W PL?

    Pete's statement that the factor depends on the amount of polarized light sounds logical but I believe it is incorrect. The factor is the same regardless of the amount of polarized light. See, e.g., Adams, "The Camera," p. 169. "The filter factor for a polarizer is usually 2.5; it is not correct to assume that the exposure factor increases as the amount of polarization increases, since this would result in overexposure of the non-polarized areas."
    Brian Ellis
    Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
    a mile away and you'll have their shoes.

  6. #6

    Join Date
    Mar 2001
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    92

    Exposure factor of B&W PL?

    I use a polarizer quite a bit and I allow 2.5 stops for it. I shoot 4x5 transparencies and that factor is right most always. you can meter through it if you want to be sure.

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