BetterPhoto Q&A
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Photography Question 
Laura Watts

Flash: Dedicated Vs. Non-Dedicated

What is the difference between a dedicated flash and a non-dedicated flash?

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5/5/2005 7:28:20 AM

Kerry L. Walker   In simple terms, a dedicated flash talks to your camera and listens to it. Depending on your flash and your camera, a dedicated flash may set the camera at flash sync, read the light off the film plane and shut itself off when enough light reached the film plane, set the aperture in program mode and even assist your autofocus.

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5/5/2005 7:31:05 AM

Jon Close
BetterPhoto Member Since: 5/18/2000
  A dedicated flash will work with only one brand or line of cameras. It will have several contacts around the large central one in the hotshoe connection. The location and electronic communication protocol varies by camera brand so for example a Nikon-dedicated flash will not work on a Minolta. Sometimes the dedication is very specific - such as the Canon digital EOS cameras can only use flashes with Canon's E-TTL dedication. They cannot use flashes dedicated to Canon's traditional TTL or A-TTL.
A non-dedicated flash has just the one large central contact in the hotshoe, or connects to the camera via the standarized PC sync cord. The only communication between the camera and flash is shorting that connection to make it fire. Using a non-dedicated flash you have to manually set the lens aperture and shutter speed.

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5/5/2005 9:24:12 AM

Amy McCarthy   I have a related question. How do I know what my camera's flash sync is? I have an old Pentax Spotmatic, an older Mamiya something or other and a Canon Rebel 2000. I don't have the manuals for any of them. Also, why is flash sync important?

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6/27/2005 10:39:13 AM

Christopher A. Vedros
BetterPhoto Member Since: 3/14/2005
  Amy, on the older cameras, look at the shutter speed dial, and see if one of the speeds has an X next to it. Many cameras used this to indicate the flash sync speed.

I think the Canon Rebel 2000 has a built-in flash. If so, set the camera to full auto (green box) or P, and pop up the flash. Check to see what shutter speed the camera has auto set to. It will probably be 1/60. I think most of the EOS cameras at that level sync between 1/60 and 1/200.

In general, the flash sync speed is the speed (or range of speeds) at which the camera can ensure that the shutter movement and the flash fire will occur simultaneously. When an exposure is taken where the flash is not sync'd with the shutter, you may end up with a black band across the image or a black top or bottom portion of the image, depending on how the shutter travels.

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6/27/2005 10:57:12 AM

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