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Thread: Canon AV mode flash sync speed

  1. #1

    Default Canon AV mode flash sync speed

    Hi all,

    i have some question regarding the sync speed for my canon 450D.
    Whenever i set to <P> mode or auto mode with my flash activated, my shutter speed would be 1/60 with f2.8 but when i set the camera mode from <p> mode to AV mode, the shutter speed would be ~1sec althought the aperture remains at f2.8. I had set AV in C.fn to auto. iissit suppose for canon camera to work in this way cos i heard from my fren that for nikon the shutter speed will be sync with the flash when the mode is set to aperture priority. Thanks newbie here...


  2. #2

    Default Re: Canon AV mode flash sync speed

    Quote Originally Posted by teck21 View Post
    Hi all,

    i have some question regarding the sync speed for my canon 450D.
    Whenever i set to <P> mode or auto mode with my flash activated, my shutter speed would be 1/60 with f2.8 but when i set the camera mode from <p> mode to AV mode, the shutter speed would be ~1sec althought the aperture remains at f2.8. I had set AV in C.fn to auto. iissit suppose for canon camera to work in this way cos i heard from my fren that for nikon the shutter speed will be sync with the flash when the mode is set to aperture priority. Thanks newbie here...

    Here's a good source of information on the Canon EOS flash system, http://photonotes.org/articles/eos-flash/

  3. #3

    Default Re: Canon AV mode flash sync speed

    Increase ISO speed to achieve handholding speed. In low light, Av mode reduces ambient exposure by 1 stop when flash is used.

  4. #4
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    Default Re: Canon AV mode flash sync speed

    Quote Originally Posted by grantyale View Post
    Increase ISO speed to achieve handholding speed. In low light, Av mode reduces ambient exposure by 1 stop when flash is used.
    How much do you want to increase from 1s to handhold speed of let's say 1/30sec? If you start with 1 sec at ISO 100 you'll get ISO 3200 for 1/30s. Not sure if such a noisy image is what TS wants to achieve.
    Better read the documentation behind the link. The metering mode here is also important to determine which part of the image is used for the exposure metering. Finally, the exposure meter doesn't need to show 0EV when flash is used. One can get good images with -2EV and FEC at +1. Can be done in Av or M.

  5. #5

    Default Re: Canon AV mode flash sync speed

    Quote Originally Posted by 2evans View Post
    Here's a good source of information on the Canon EOS flash system, http://photonotes.org/articles/eos-flash/
    wow that's was a very good piece of information thanks for sharing... now then i know they will not assume flash is on when dial is set to Av

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