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Old Mar 21, 2008, 10:26 AM   #1
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hey! probally another dumb ? from me but whats a digital slave flash? it came with my camera (as a gift) and i dont know what it is or what it is used for! thanks in advance!
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Old Mar 21, 2008, 10:46 AM   #2
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It's an optically triggered flash designed to fire whenever it sees the camera's main flash fire (usually so you can add more flash range or get a more diffused flash compared to what the camera's built in flash provides).

Digital slaves are designed to ignore metering preflashes from digital cameras (most digital camera models use a separate flash for metering, before the flash for the actual exposure).

So any optically triggered device will need to be "digital aware" so that it knows to fire on the main flash versus the preflash. Some of them will have settings for how many preflashes to ignore (some cameras may use more than one preflash before the main flash burst).

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Old Mar 21, 2008, 10:48 AM   #3
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thanks jimc! can you give me an exapmple of when to use it? night time?
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Old Mar 21, 2008, 10:58 AM   #4
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Anytime you exceed your camera's flash range (or want better light from a flash compared to what the camera's built in flash is likely providing). Check the specifications for your camera model and you'll see flash range listed.

With most non-DSLR models, you'll usually see the range at the wide end of the zoom (least apparent magnification) and the flash range when zoomed in all the way (most apparent magnification). Flash range will decrease as you zoom in more with most lenses (because they are not as bright on their longer end).

You will need a flash in most indoor lighting for moving subjects (i.e., your people photos) with most digital camera models if you do not want motion blur from subject movement (and/or higher noise levels with loss of detail from noise reduction if you increase ISO speed too much).

A slave flash is going to be useful to increase your flash range some with most cameras. You can also position some of them away from the camera to provide more even lighting, or lighting that is not as flat as using the camera's flash alone would provide.

P.S.

You may also want to use a flash outdoors if your subject is backlit or in shadows to help illuminate them, so that you don't have as wide of an exposure difference between the brighter parts of the image and your subject.

You may also want to do the opposite (use a faster shutter speed and/or higher f/stop number for a smaller aperture and/or lower ISO speed with a flash so that your subject is the only portion of the image that is properly illuminated).

That way, you'd have a darker background with your subject in the foreground illumninated and they would be isolated from a distracting background more. If using that technique, increase shutter speed using manual exposure first to darken the rest of the exposure until you reach the fastest flash sync speed supported (since that won't impact your flash range like using a lower ISO speed or different aperture setting would).

There are many conditions where a flash can come in handy.

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