Second-curtain sync

Your camera uses mechanical devices called curtains to open and close its shutter. The default setting is for your Speedlite to fire at the beginning of the exposure, called first-curtain sync. In most cases this is just fine; however, when taking long exposures of a moving subject when using flash, the result is the subject is illuminated at the left side of the photo (assuming it is moving from left to right), and a long trail of light going from left to right in front of the moving subject makes the subject look like it is going backward. This is a situation that can occur with any photo taken where the flash takes significantly less time than the exposure.

Second-curtain sync overcomes this problem by forcing your flash to fire at the end of the exposure. The trail of light then comes behind the subject, illuminating at the end of the image, and it appears on the right-hand side (when moving from left to right across the frame).

You will probably want to use Flash Exposure Lock with this type of an image to avoid a preflash, which can meter incorrectly if your subject will be in a different place in your image between the beginning and end of the exposure. Using Bulb mode can work well with second-curtain sync, as well. Note also that you cannot use a stroboscopic effect with the second-curtain sync mode.

Category: Flashes

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