Sony A9 Mark III Mirrorless Camera

What is a Global Shutter?

Global shutter is a photographic technique that captures all image data simultaneously, distinguishing it from conventional shutter systems that progressively initiate and conclude exposure across the sensor. This method offers various advantages, including the elimination of the common rolling shutter distortion observed in videos and with slower electronic shutters. Another significant benefit is its compatibility with flash synchronization at virtually any shutter speed. In this context, the duration of the flash burst sets the limit, rather than the time required to close the shutter, which in turn determines the shortest duration for full sensor exposure. For instance, Sony asserts that the a9 III can sync at all shutter speeds, including ultra-fast ones up to 1/80,000 second.

Furthermore, a global shutter effectively eliminates the banding issue that can arise with progressive shutters when capturing images under flickering lights. Since the entire image is captured at precisely the same instant, there is no discrepancy in the recording of different phases of a light's flicker cycle across different parts of the image. While exceptionally high shutter speeds may capture the refresh cycle of an LED signboard, any resulting artifacts are attributed to the LEDs themselves, as the camera faithfully records a single moment in time.