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Thread: Flash Syn Speed

  1. #1
    Trevor_Tan
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    Default Flash Syn Speed

    Hi Guys,
    Got this questions on Flash Syn Speed. I'm using F80 and it got a flash syn of 1/125. From my understanding, it means that when flash is use, the highest possible speed is 1/125. And any speed above that will have banding effect as the shutter curtain not fully open when flash is trigger. (correct me if I got it wrong)

    My questions:
    1) Does this 1/125 only limit to the build-in flash and what X-contact only mean?
    2) If use SB flash (eg sb50dx or sb28) can the shutter speed be faster than 1/125?
    3) If uses bounce flash, do I need to reduce the speed of shutter slightly (slower then 1/125) or just use it at 1/125.
    4) 1/125 seem kind of slow, is there anyway to increase the speed?
    5) Just an example (not an actural case). In a bright sunny day, I wanted to shoot an a person outdoor, If I use a AP at f3.5 to throw the background out of focus, the meter required a shutter speed of say 1/500. But to remove the nasty shadow on the face, I use fill-in flash (build in). Hence the camera will reduce the speed will reduce to 1/125 (right?). In this case, will the picture be overexposed? I got a feeling that the person will be correctly expose but background will be overexpose. How can I achive a better picture if I want to maintain that kind of f3.5 DOF.

    Thanks for any info input.

  2. #2
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    3) you adjust the aperture rather than the shutter speed.
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  3. #3
    Trevor_Tan
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    Originally posted by mpenza
    3) you adjust the aperture rather than the shutter speed.
    Err so is decrease the aperture size or increase? And why?

  4. #4
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    increase aperture size (reduce the number).

    as to why, ckiang explained it before: http://forums.clubsnap.org/showthrea...ght=flash+sync

    Flash sync speed on focal-plane shutter cameras like SLRs and interchangeable lens rangefinders are between 1/60 to 1/250. On in-lens shutters and electronic shutters like DCs, it can actually be anything. Shutter speed does not affect flash exposure. The manual should state the recommended flash sync speed.

    That said, bear in mind that if your ambient light reading requires a shutter speed of say, 1/125 and you are trying to use 1/60, you will get overexposure, flash or not. In that case, lower your aperture.
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  5. #5

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    1) Both built in and hotshoe
    2) No, see above.
    3) Depends on how much ambient light you want to let in.
    4) Nope, you're stuck with 1/125, unless you change cameras.

  6. #6
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    Default Re: Flash Syn Speed

    Originally posted by Trevor_Tan
    Hi Guys,
    5) Just an example (not an actural case). In a bright sunny day, I wanted to shoot an a person outdoor, If I use a AP at f3.5 to throw the background out of focus, the meter required a shutter speed of say 1/500. But to remove the nasty shadow on the face, I use fill-in flash (build in). Hence the camera will reduce the speed will reduce to 1/125 (right?). In this case, will the picture be overexposed? I got a feeling that the person will be correctly expose but background will be overexpose. How can I achive a better picture if I want to maintain that kind of f3.5 DOF.

    Thanks for any info input.
    The maximum synch speed is fixed on Rangefinders and 35mm SLR's or any camera that uses a film plane shutter. Leaf shutters (in the lens) and non SLR type digital cameras don't have the synch restrictions.

    X contact is for Electronic Flash Units, the other contact type is M or B for flash bulbs.

    As for 5). Yes it will reduce the speed to 1/125 in the case of the F80 and the following are solutions.

    1) Use a slower film such as 50 ISO. If that's not possible then consider option 2.

    2) Use reflectors instead of flash fill.
    The Ang Moh from Hell
    Professional Photography - many are called, few are chosen!

  7. #7
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    If it's going to over expose at the syn speed and you don't want to narrow down your aperture, you can always get NDs to help.

    =)

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