High-speed sync

Normally, flashes are set to operate with a camera shutter speed of 1/250 second or slower. If you have a flash attached to your Canon dSLR, you will not be able to set the shutter speed on your camera to a speed faster than 1/250 second. Your camera’s shutter needs a little time to open and close its two “curtains” that allow the image to be exposed onto the sensor. 1/250 is the fastest that it can normally create an exposure and synchronize the flash with it.

However, there may be some instances where you will want to use your flash with a faster shutter speed. For example, what if you want to add a little light to a subject’s face on a very sunny day as fill flash (extra light meant to offset shadows or other darker areas of a normally well-lit subject)? In this situation, you might very well have your shutter speed set for 1/500 second or faster.

Enter high-speed sync, or FP (focal plane) flash. This is an override setting that allows you to shoot a flash at shutter speeds beyond your camera’s limit of 1/250 second. This changes the way your camera’s “curtains” open and close and allows you to shoot a flash image at virtually any shutter speed. What do you lose in this situation? Power. Your flash will fire only with diminished power, lower than it would otherwise use for a given exposure. And, since you’re running in manual flash mode, your flash and camera won’t be using ETTL II.

Focal plane flash works with the 430EX and the 580EX II (and their predecessors), and is controlled by a setting on the back of the flash.

Category: Flashes

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