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Thread: Multiple Exposure Question

  1. #11

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    Re: Multiple Exposure Question

    This subject has been throughly discussed here (at length) at least a couple times over the past couple of years... Please go through the archives and find it...

    No matter what, even if you photograph something on a black background, it will build-up base and overall density differently than a single exposure, and not the same (much flatter contrast etc), and I really don't understand why so many exposures would be needed on a sheet of film, when other sheets could be shot, and combined later somehow... (Limited subject matter/choices & overall density problems...) There are times to split exposures (CC filter changes/color, movement, adding elements, montage, etc), but without masking, the image gets terribly complicated, and harder to print every step of the way...

    I like to put problems before solutions, instead of solutions that are looking for a problem (but that's just me)... And try not to hold technical concepts as "koool", and that being the underlining reason to do it... (Or I could be printing epic photographs on the heads of pins... Cool, right!?!!!)

    (Don't mind me, I'm in a weird mood today...)

    Steve K

  2. #12
    Jac@stafford.net's Avatar
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    Re: Multiple Exposure Question

    Quote Originally Posted by xkaes View Post
    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!!!
    Were you ignoring that each exposure accumulates to the final result?

  3. #13

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    Re: Multiple Exposure Question

    Quote Originally Posted by LabRat View Post
    I really don't understand why so many exposures would be needed on a sheet of film
    Here's one that I've used myself many times. I'm at the beach with a bunch of rocks. I can take one exposure at short or long shutter speeds -- at whatever f-stop. With the longer exposures I get more blurrrrr of the waves crashing. Or I can take 64 exposures of the same scene with a short exposure time with the waves frozen at different positions. Completely different effect.

  4. #14

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    Re: Multiple Exposure Question

    Quote Originally Posted by Jac@stafford.net View Post
    Were you ignoring that each exposure accumulates to the final result?
    Last time I checked 1/8 + 1/8 = 2/8 = 1/4. But it's been a while since I took calculus.

  5. #15

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    Re: Multiple Exposure Question

    Quote Originally Posted by xkaes View Post
    Here's one that I've used myself many times. I'm at the beach with a bunch of rocks. I can take one exposure at short or long shutter speeds -- at whatever f-stop. With the longer exposures I get more blurrrrr of the waves crashing. Or I can take 64 exposures of the same scene with a short exposure time with the waves frozen at different positions. Completely different effect.
    Just more complicated... (You mean 64 underexposed exposures???)

    Get to the beach much???

    Steve K

  6. #16

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    Re: Multiple Exposure Question

    Quote Originally Posted by LabRat View Post
    Just more complicated... (You mean 64 underexposed exposures???)

    Get to the beach much???

    Steve K
    Yeah, I know, math is complicated. Even more complex than getting to the beach. FYI, it works on rivers and streams as well, as I and many other photographers, who know how to divide, can attest. Go buy a calculator and try it yourself.

  7. #17

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    Re: Multiple Exposure Question

    Quote Originally Posted by xkaes View Post
    Yeah, I know, math is complicated. Even more complex than getting to the beach. FYI, it works on rivers and streams as well, as I and many other photographers, who know how to divide, can attest. Go buy a calculator and try it yourself.
    Go figure...

    Steve K

  8. #18

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    Re: Multiple Exposure Question

    Quote Originally Posted by xkaes View Post
    Here's one that I've used myself many times. I'm at the beach with a bunch of rocks. I can take one exposure at short or long shutter speeds -- at whatever f-stop. With the longer exposures I get more blurrrrr of the waves crashing. Or I can take 64 exposures of the same scene with a short exposure time with the waves frozen at different positions. Completely different effect.
    This is exactly what I am trying to achieve. So going back to my initial question, do I have the math right in order to calculate the number of required exposures

  9. #19

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    Re: Multiple Exposure Question

    Quote Originally Posted by IanBarber View Post
    This is exactly what I am trying to achieve. So going back to my initial question, do I have the math right in order to calculate the number of required exposures
    Ian,

    Your math is correct. The way xkaes figures, one comes up with 32 exposures, but the difference is trivial. In this case, Jac is wrong (uncharacteristically). You need a lot more than five exposures at 1/125 to equal 1/4 sec. Think of it this way: 1/4 second is 250 milliseconds; 1/125 second is 8 milliseconds. Divide 250 by 8 to find how many exposures you need. Answer: 31.25.

    However, keep in mind that there is such a thing as the intermittency effect, which basically states that many short exposures do not exactly equal one long exposure. If I were in your place, I would use 40 or more exposures.

    FWIW, I use cumulative exposures to make up one total exposure all the time, although usually only 4-10 different exposures. It's a great way to stop wind, keep passers-by and cars out of your shots and get rid of blinking lights.

    Best,

    Doremus

  10. #20

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    Re: Multiple Exposure Question

    Quote Originally Posted by Doremus Scudder View Post
    Ian,

    Your math is correct. The way xkaes figures, one comes up with 32 exposures, but the difference is trivial. In this case, Jac is wrong (uncharacteristically). You need a lot more than five exposures at 1/125 to equal 1/4 sec. Think of it this way: 1/4 second is 250 milliseconds; 1/125 second is 8 milliseconds. Divide 250 by 8 to find how many exposures you need. Answer: 31.25.

    However, keep in mind that there is such a thing as the intermittency effect, which basically states that many short exposures do not exactly equal one long exposure. If I were in your place, I would use 40 or more exposures.

    FWIW, I use cumulative exposures to make up one total exposure all the time, although usually only 4-10 different exposures. It's a great way to stop wind, keep passers-by and cars out of your shots and get rid of blinking lights.

    Best,

    Doremus
    Thanks for the clarification, I was not aware of the intermittency effect, is it just a case of adding a few more to take this into effect or do you calculate it through a formula

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