Front curtain synchronization occurs when a flash fires immediately after the front curtain of a focal plane shutter has completed its travel across the film or digital sensor plane. This ensures that the flash exposes the entire frame evenly at the start of the exposure.
This technique is commonly used in flash photography to freeze motion while still capturing ambient light in the background. Understanding front curtain synchronization helps photographers control exposure, prevent motion blur, and achieve balanced lighting in both studio and outdoor settings.