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Thread: Diff. between exposure time and shuttle speed value?

  1. #1

    Default Diff. between exposure time and shuttle speed value?

    Hi, I was browsing a photo gallery and checking out the EXIF data of the photographs as well.

    In the photo EXIF data table it listed the exposure time and the shuttle speed value of the shot.

    eg. one of the photo has a exposure time of 1/250 sec and the shutter speed value was listed as 1/128sec.

    How can the exposure time be 1/250 when the shutter speed is only 1/128?
    I am getting a little confuse here. What is the different between these two values?

  2. #2


    This could be because the camera is an SLR that has both a mechanical shutter and an electronic shutter (e.g., the Nikon D70).

    Essentially, with such cameras, there are two ways of regulating the amount of time the capture element (film or CCD) is exposed to the light entering from the lens. You can regulate how long the mechanical shutter opens; you can also (or instead of) open the mechanical shutter, and while it is open, regulate how long the CCD is exposed to the light by electronics. This is the "electronic" shutter.

    For example, in the D70, at speeds below X, the mechanical shutter operates to regulate the amount of time light hits the capture element (film or CCD). At speeds above X, the mechanical shutter fires at a high speed, and the electronic shutter regulates the amount of time the light hits the capture element.

    In this case, the "exposure" time would correspond to the electronic shutter time, while the "shutter" speed is the mechanical shutter speed. Note that cameras such as the Canon Digital Rebel have only a mechanical shutter - and that this explains why the D70 has a higher flash sync speed than the Digital Rebel.

    Hope this helps.

  3. #3


    Thanks for your reply! Yes it does help. Never know there is such thing as mechanical and electronic shutters..

    But the photos I was browsing was taken using canon G5. Didn't know it comes with such features..


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