Flash Shutter Sync - Water Droplet

Flash Mechanics: Shutter Sync

If you’re getting interested in flash photography, a lot of unfamiliar terms may pop up: sync-speed, high-speed sync, rear-curtain sync, to name a few. It’s a lot easier to get a grasp on the terms if you have a better understanding of how flashes work with your camera’s shutter, and ultimately, how your camera’s shutter works. To help explain things, I’ve made this quick video.

This video is intended to be more of an introduction to the concepts involved, rather than instruction on specific techniques.

For what it’s worth, “Sync-Speed” is also frequently called “X-sync” speed, though X-sync usually refers specifically to first-curtain sync.

As usual, if you have any questions or comments (I’m always curious to hear whether anyone has actually watched these things), please let me know in the comments section below.

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  • That was easily the best animated demonstration of the 1st and 2nd curtain mechanism that I have seen so far. My only wish is that you could break down the high-speed sync part even more to demonstrate why the top and bottom of the frame get the same amount of light as the middle of the frame. Thanks!

    • Hi Kenneth,

      Glad you found it useful :) As for the high-speed sync part: the reason that the whole frame gets the same amount of light, even though it’s not all exposed at the same time, is that the flash isn’t working as a “flash” anymore, in HSS mode. It’s more like flipping on a light-switch, and there’s a light on for the full duration of the exposure, and then it turns off again after the exposure. With HSS, the light is a continuous brightness for the whole shot.

      – Matthew

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