A stacked sensor is a type of image sensor used in digital cameras, including mirrorless cameras. It is called a “stacked” sensor because it is composed of multiple layers of photodetectors and other components, which are stacked on top of each other in a vertical arrangement. This design allows for a smaller, more compact sensor, as well as faster image processing and improved performance in certain areas.

One of the main benefits of a stacked sensor is its ability to capture high-speed images and video. Because the layers of the sensor are vertically stacked, data can be transferred more quickly between them, allowing for faster image processing and continuous shooting speeds. This can be especially useful for photographers who need to capture fast-moving subjects or action scenes.

Stacked sensors also offer improved low-light performance, as they are able to capture more light due to their larger surface area. This can result in better image quality in dimly-lit conditions, as well as reduced noise and greater dynamic range.

Another advantage of stacked sensors is their ability to incorporate additional features and functions into the sensor itself. These can include phase detection autofocus (PDAF) pixels, image stabilization (IS) elements, and other components that would normally take up space on the main image sensor. This can allow for more compact camera bodies and improved performance in certain areas.

Overall, stacked sensors offer a number of benefits for photographers, including faster image processing, improved low-light performance, and the ability to incorporate additional features into the sensor itself. These advantages make them an attractive choice for mirrorless cameras, as well as other types of digital cameras.