Canon Flash and EXIF

mercphotomercphoto Registered Users Posts: 4,550 Major grins
edited November 2, 2005 in Accessories
Hope I posted in the right category. Anyway to tell how hard the flash fired by looking at the metadata, either in a JPG or the RAW file, or by looking at info on the camera or flash itself? Canon 20D and a 580EX Speedlight. What I'd like to be able to do is fire the flash in ETTL2 mode, then determine what flash power was used, then go manual on the flash after that. Kinda like using the camera as a cheap built-in flash meter.
Bill Jurasz - Mercury Photography - Cedar Park, TX
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Comments

  • pathfinderpathfinder Super Moderators Posts: 14,708 moderator
    edited November 2, 2005
    Bill, I have not studied the exif format enough to really know whether that data is recorded or not, but i have never heard of it. But how about this as a work around,

    Since you know your subject distance, and the aperture and F stop used, can't you calculate the approx guide number from that information if you assume the flash exposure was responsible for the lighting ( ie ambient light was not a significant contribution to the exposure).

    Even better, with a 580ex, just shoot with the camera set in manual mode, and the flash will automatically meter and light the shot for you if it can possibly meet the manual shutter and aperture you set.( It usually can - try it and see!) You can dial in -FEC as needed also

    If the shutter speed is set faster than 1/200, you will need to adjust the 580 to high-speeed or focal plane exposure mode.
    Pathfinder - www.pathfinder.smugmug.com

    Moderator of the Technique Forum and Finishing School on Dgrin
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