Why is a Global Shutter a Big Deal - Explained Simply

Imagine you're taking a picture of a fast-moving subject, such as a car racing or a ball being thrown. With a regular camera, the sensor captures the image line by line, from top to bottom. This is like reading a book one line at a time. By the time the camera finishes reading the bottom line, the subject might have moved, causing the image to appear distorted.

A global shutter, on the other hand, is like taking a snapshot with an old-fashioned film camera. All the pixels on the sensor are exposed at the same time, capturing the entire scene in an instant. This prevents distortion caused by movement, especially when photographing fast-moving objects or scenes with rolling lines, such as a propeller.

With a global shutter, the entire image is captured at once, so there's no distortion, even if there's movement during the exposure. This is why global shutters are essential for high-speed photography, sports photography, and situations where precise timing is crucial. Global shutters also provide higher flash speed sync which can give portrait photographers more control.

Flash sync speed is the fastest shutter speed your camera can use with a flash without causing black bands or uneven exposure in the image. This is because the flash emits a burst of light very quickly, and if the shutter is still moving when the flash fires, only a portion of the sensor will be exposed to the light.

Here's why flash sync speed is important:

Freezing motion: When photographing fast-moving subjects, like athletes or dancers, you need a fast shutter speed to freeze the action and prevent blur. However, if your shutter speed is too fast, it may exceed your camera's flash sync speed, resulting in black bands or uneven exposure.

Controlling ambient light: In bright outdoor conditions, you may want to use a flash to fill in shadows or balance the exposure. However, if your shutter speed is too slow, the ambient light will also contribute to the exposure, potentially overexposing the image. A faster flash sync speed allows you to use a faster shutter speed to reduce the impact of ambient light.

Creative effects: Sometimes, you might intentionally use a slow shutter speed with a flash to create creative effects, such as blurring motion or adding light streaks. However, if your camera's flash sync speed is too slow, you may not have the flexibility to achieve these effects.

The New Sony a9iii offers flash sync speed to 1/80,000 second because it offers a global shutter.