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Thread: Multiple Exposure Question

  1. #1

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    Multiple Exposure Question

    I am wanting to try out some multiple exposure on the same negative of the same scene on some coastal work tomorrow.

    Scenario:
    The meter reading is 1/4 second at f22 but to use 1/125th second at f22, divide 125 by 4, the answer is 31 multiple exposures at 1/125th.

    Is there anything else I need to be aware of or will the 31 exposures at 1/125th give me the same density as a single exposure at 1/4

  2. #2
    Jac@stafford.net's Avatar
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    Re: Multiple Exposure Question

    Nooooo. Exposures are not linear. The good news is ~ five exposures.

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    Re: Multiple Exposure Question

    Quote Originally Posted by Jac@stafford.net View Post
    Nooooo. Exposures are not linear. The good news is ~ five exposures.
    Can you explain how you arrived at 5 please

  4. #4
    Jac@stafford.net's Avatar
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    Re: Multiple Exposure Question

    Quote Originally Posted by IanBarber View Post
    Can you explain how you arrived at 5 please
    1/4 to 1/8
    1/8 to 1/15
    1/15 to 1/30
    1/30 to 1/60
    1/60 to 1/125

    Five stops

    I am sure someone will correct me if I am wrong.
    .

  5. #5

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    Re: Multiple Exposure Question

    Quote Originally Posted by Jac@stafford.net View Post
    1/4 to 1/8
    1/8 to 1/15
    1/15 to 1/30
    1/30 to 1/60
    1/60 to 1/125

    Five stops

    What would happen if I took 31 exposures at 1/125th. Would the density on the negative not build up to equal one exposure at 1/4

  6. #6

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    Re: Multiple Exposure Question

    And then some.

  7. #7

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    Re: Multiple Exposure Question

    I'd never given it much thought but it seems like it would be way over exposed. If I did feel the need to put 31 exposures on a sheet of film though I'd start with close to proper exposure and build (or subtract) from there likely using a combination of film, developing, and neutral density. The OP seems to want to use 1/125 so shutter speed doesn't seem an option. Could be an interesting experiment, not for me but maybe someone somewhere.

  8. #8
    Jac@stafford.net's Avatar
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    Re: Multiple Exposure Question

    Quote Originally Posted by jamesaz View Post
    I'd never given it much thought but it seems like it would be way over exposed. If I did feel the need to put 31 exposures on a sheet of film though I'd start with close to proper exposure and build (or subtract) from there likely using a combination of film, developing, and neutral density. The OP seems to want to use 1/125 so shutter speed doesn't seem an option. Could be an interesting experiment, not for me but maybe someone somewhere.
    The OP is not wanting to make 31 exposures. He simply wants to know how many exposures to equal a certain exposure.

  9. #9

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    Re: Multiple Exposure Question

    5 stops is correct, but stops are on a logarithmic scale with a base of 2: each stop doubles the exposure; shutter speeds are on a linear scale , though the speeds on the dial have been chosen to reflect a doubling with each step (with slight fudging, e.g. 125th should actually be 1/128th). So 5 stops amounts to 2 to the 5th times the exposure which is equal to 32.

    However, not all multiple exposures act linearly, as film tends to have a minimum exposure threshold, and the shorter exposures might not meet it in the shadows. You may find a bit higher contrast with the multiple exposures, and deeper shadows. Experiment to find out. Ansel Adams used pre-exposure to provide a minimum exposure to control contrast in certain situations for this reason. Pre-exposure is using an out of focus single tone subject placed at Zone 1 to give the entire piece of film an exposure equal to base black. It is out of focus to be sure there is no texture recorded.

  10. #10

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    Re: Multiple Exposure Question

    1/4 second at f22 - 1 exposure
    1/8 second at f22 - 2 exposures
    1/15 second at f22 - 4 exposures
    1/30 second at f22 - 8 exposures
    1/60 second at f22 - 16 exposures
    1/125 second at f22 - 32 exposures

    You were WAY off!!!

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