BSI-CMOS Sensor
Sigma fp L features a 61 megapixel Full Frame BSI-CMOS sensor with dimensions of 36 x 24 mm and a total area of 864 mm2. Its native ISO range is 100 - 25,600 and expands to 6 - 102,400 in boosted mode.
The camera has BSI-CMOS sensor, short for Backside Illuminated Complementary Metal-Oxide-Semiconductor sensor. In traditional CMOS sensors, the wiring and circuitry are located on the front side of the sensor, which can block some of the incoming light. BSI technology flips this design by placing the photosensitive elements (pixels) on the backside of the sensor, allowing more light to reach the pixels. This significantly enhances light sensitivity and improves low-light performance. BSI-CMOS sensors are particularly effective in low-light conditions, as they can capture more light, resulting in brighter and less noisy images. This makes them well-suited for indoor and night photography. BSI-CMOS sensors deliver a higher SNR and reduced cross-talk.
Here is a sensor size comparison chart where you can see how Sigma fp L's Full Frame sensor compares with other types of sensors: