Using flash to freeze motion

[csphua]

Hi all,


If my target is not posing for the shot, I know I should set the shutter speed to 1/60 or faster to avoid motion blur. If I shoot indoor using 580EX II, can I set the shutter speed to slower speed (perhaps 1/40) to allow more light to enter my kit lens? Will flash in this case able to avoid motion blur when I use lower shutter speed?

[neuroanatomist]

That's completely dependent on how much ambient light there is in the room. If it's pitch black, flash will eliminate motion blur. If there's enough ambient light to illuminate the subject with the aperture selected, and the subject is moving, 1/40 s will give you some blur. You might be able to get away with 1/30 s if the subject is posing/holding still. If it's a toddler running around the room, you'll need 1/125 or faster. You can also use a slow shutter and the C.Fn setting for second-curtain sync and then the motion blur will be in the proper direction (behind the subject) as a creative effect.

[Sean Setters]

Hi all,


If my target is not posing for the shot, I know I should set the shutter speed to 1/60 or faster to avoid motion blur. If I shoot indoor using 580EX II, can I set the shutter speed to slower speed (perhaps 1/40) to allow more light to enter my kit lens? Will flash in this case able to avoid motion blur when I use lower shutter speed?
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Neuroanatomist is correct. If ambient is adding to the exposure, you won't be able to freeze motion using the flash. My suggestion is to bump up the ISO and use a shorter shutter speed. Today's cameras have come a long way in the ISO noise department--you might as well make use of the latest and greatest in technology (that is, if you have a relatively recent camera).