You usually place the camera in manual mode, choose a shutter speed of around 1/200 (the max sync speed of your brand of camera), and then set the lens aperture and the flash so they match. The flash has a sensor that measures the amount of light reflected back to the flash (not the sensor) and turns itself off. When you take the picture, the camera tells the camera to turn on, but that's all.
To use an automatic flash, you choose a lens aperture (typically f2.8, f5.6, etc.) and then make the same setting on the flash. It does not talk to the camera, hence can work with almost any brand of camera. A TTL flash usually has multiple contacts on the bottom of the hot shoe.Īn "automatic" flash is a much simpler beast. This is often call TTL, or "through the lens" control. Note that this arrangement will work for any aperture, because it is dependent on the amount of light hitting the sensor. When you take a picture, the camera measures the amount of light hitting the sensor and when exposure is "correct" tells the flash to turn off. As you chance the focal length of a zoom lens the camera controls the flash zoom head and sets it accordingly. This is an "automatic" flash, and not a "dedicated" flash.Ī "dedicated" flash is designed to work with a particular brand of camera (Canon, Nikon, Pentax, etc,) by communicating with the camera. I do not own one, and google wasn't much help either.
I'm guessing this is because it isn't a Canon flash. I put batteries in and the flash unit acknowledges them, but the camera doesn't.
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