Rolling Shutter and Global Shutter: Readout Methods, Stack Structure, and Shooting Trade-offs

First, distinguish between rolling shutter and global shutter readout methods

Sony's sensor engineers differentiate the two methods as follows: rolling shutter exposes and reads pixels line by line from top to bottom, while global shutter exposes and reads all pixels simultaneously. Here, the comparison is about the sensor's working method, not a synonym for "mechanical shutter" and "electronic shutter."〔G-SHUTTER-01〕

Possible image effects of rolling readout

Line-by-line reading causes different positions in the image to correspond to slightly different acquisition times. Sony uses the tilted distortion of a train photographed from the side to illustrate rolling shutter distortion; their engineering documentation also mentions that, under certain shooting conditions, LED or fluorescent lights may show stripes, and multiple flash triggers at the same time may also result in flash bands. The results vary depending on the camera, readout method, light source, and shooting conditions, and all readout times cannot be inferred from shutter speed alone.〔G-SHUTTER-02〕

Stack structure and shutter readout are different descriptive dimensions

"Stacked" describes the sensor structure, while "global shutter" describes the timing of pixel exposure and readout. Sony's product materials for the α9 III describe it as approximately 24.6 million effective pixels, a full-frame stacked CMOS global shutter sensor with built-in memory. This is the specific implementation of this model and cannot be used to infer that all stacked sensors use global shutters, nor to infer the readout speed of other models.〔G-SHUTTER-03〕

Weigh shooting needs according to model information

For fast-moving subjects or scenes prone to flickering lights, first check the camera manual for global shutter, readout speed, or anti-flicker notes, and then verify with actual shooting conditions. A global shutter does not automatically mean there are no image artifacts. Sony's engineering team points out that the global shutter implementation of the α9 III consumes more power than line-by-line reading and affects the number of shots per charge; this trade-off should be limited to the manufacturer's information for this model and cannot be generalized as a battery conclusion for all global shutter cameras.〔G-SHUTTER-04〕