April 13, 2024

What is Global Shutter? And How It Works


The recent announcement of the Sony a9III has sparked widespread interest in global shutter technology. This innovative camera, equipped with a global shutter sensor, is the first full-frame mirrorless camera to offer this advanced feature. Before the A9III, global shutter was a niche player for video, but Sony’s move has democratized it, starting conversations about its impact for photographers. 

This article explores the intricacies of global shutter, delving into its workings, advantages, and vast potential for the imaging industry and creatives.

What is Global Shutter?

Global shutter exposes all pixels on a sensor simultaneously, unlike the gradual scanning of rolling shutters. Think of it as a snapshot, capturing the entire scene at once, dodging the distortions typical of fast-paced action. 

Crucial in photography and filmmaking, this technology, exemplified by the Sony a9III, ensures precision in dynamic moments, eliminating the notorious “jello effect” that often plagues traditional rolling shutters when panning quickly or trying to capture a fast-moving subject.

Photo is a screenshot from AdoramaTV’s Sony a9 III video

How Does Global Shutter Work?

Imagine a camera sensor as a grid of light detectors. Global shutter works like a flash photograph, where an electronic signal quickly turns off each pixel simultaneously, preventing light from being recorded. When the shutter opens, light hits all detectors at once, capturing the entire scene in one instant.

When the shutter opens, light hits all detectors at once, freezing the moment in flash-photography style. The result is distortion-free imagery, ideal for sports, wildlife, or any action-packed scene. This global shutter tech, while a tad more intricate and costly to craft, ensures precise flash exposures. 

The Sony a9III emerges as a groundbreaking solution to the challenges posed by rolling shutters, marking the debut of a global shutter in a full-frame mirrorless camera. The stacked CMOS sensor not only achieves this milestone but offers exceptional processing power and speed.

Thanks to these technological advancements, the camera boasts impressive capabilities, including shooting at 120fps in 14-bit RAW for up to 192 frames with real-time autofocus, flash sync at any shutter speed, and a maximum shutter speed of 1/80000.

The global shutter mechanism offers several benefits over rolling shutters:

  • Eliminates rolling shutter distortion: Global shutter captures the entire scene at once, preventing warped lines caused by rolling shutters.
  • No blackout: Unlike rolling shutters, global shutters don’t cause a blackout in the viewfinder, making it easier to track subjects.
  • Accurate flash exposures: Global shutter ensures that the flash is synchronized with the shutter speed, resulting in accurate flash exposures.
  • Ideal for fast-moving subjects: The global shutter’s ability to freeze fast-moving subjects without distortion makes it ideal for action photography.
The diaphragm of a camera lens aperture,digital DSLR photography lens
Photo from Adobe Stock

Other Shutters

Electronic shutters are powered by electronic signals that pair with their mechanical counterparts, bringing speed and enabling swift shutter speeds but adding its own unique issue—occasional banding.

Old-school mechanical shutters open and close, controlling exposure time with a hint of noise. Operating line by line or with a physical curtain, they differ from the global shutter, which exposes the entire sensor at once. 

rolling shutter is a type of image capture mechanism that is generally more cost effective and most commonly used on CMOS sensors. Unlike global shutters, rolling shutters also scan the sensor line by line, capturing the image in a sequential manner. 

Understanding these shutter siblings provides perspective on the global shutter’s prowess. Each has its rhythm, but the global shutter steals the spotlight with its simultaneous exposure magic, eliminating distortions and blackouts but resulting in precise flash exposure for a seamless photographic performance.

Benefits of Global Shutter

Unlike rolling shutters, global shutters maintain a clear view throughout the scanning process, eliminating blackout disruptions in the viewfinder. In the dimly lit realms of low-light photography, global shutters become a guiding light, capturing sharp, distortion-free images at faster shutter speeds and minimizing reliance on high ISO settings, thereby reducing noise. 

These shutters also play a pivotal role in achieving an authentic film look by capturing the entire scene simultaneously and erasing artifacts. Moreover, solo creators may find an added advantage with global shutters—a potential reduction in strobing with lights that are not film-friendly, translating into downstream cost savings. 

Photo from Adobe Stock

Real World Global Shutter Examples:

  • Sports and Action Photography: Global shutter’s ability to freeze motion without distortion makes it ideal to capture athletes in action, such as runners crossing the finish line, soccer players kicking the ball, or basketball players dunking.
  • Wildlife Photography: Tracking and capturing elusive animals in their natural habitat, such as birds in flight, cheetahs sprinting, or elephants roaming, requires the ability to freeze motion and eliminate artifacts. Global Shutter enables wildlife photographers to capture these moments with exceptional clarity and detail.
  • Studio Photography: Ensure consistent and accurate flash synchronization for high-quality, balanced lighting.
  • Low-Light Photography: Maintain image quality in dimly lit environments without compromising sharpness.

How Might Global Shutter Affect Photography?

Global shutter has the potential to become the new standard for high-performance cameras, offering a significant advantage in image quality and performance. Envision distortion-free images in dynamic genres like sports or wildlife. Beyond photography, its precision may revolutionize object tracking, motion analysis, and autofocus capabilities.

As global shutter technology continues to develop and mature, camera design and manufacturing is bound to grow, broadening access to global shutter-equipped cameras. The overall impact could usher in a revolutionary era of high-quality, distortion-free imaging, shaping the future of visual storytelling with this technological advancement. 

Final Thoughts

Global shutter stands as a pivotal stride in camera technology, bestowing a spectrum of benefits upon users. Continuous improvements in resolution, sensitivity, and cost position global shutters for increased adoption among photographers and content creators. 

Christopher Piccione

Christopher is a freelance podcast and video editor, actor, and screenplay writer living in New York City. He is incredibly passionate about traveling, hobby photography, and filmmaking when he can afford it. A fan of dogs, cats, & a mean burrito. You can occasionally catch him on TV, the silver screen, or a film festival near you.

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