The CCD: The Pioneer
The CCD (Charge-Coupled Device) transfers electrical charges from one photosite to another sequentially, like a chain of buckets passed hand to hand. A single analog-to-digital converter processes the entire signal.
This approach ensured remarkable response uniformity and very low noise, but at the cost of slow reading speeds, high energy consumption, and blooming sensitivity.
The CMOS: The Modern Revolution
Each photosite on a CMOS sensor has its own amplifier and converter. Reading is parallel and direct, enabling very high frame rates and reduced power consumption.
Key Advantages: Speed (parallel reading for 4K/8K), Energy (extended dive time), Cost (standard manufacturing), Flexibility (autofocus on the sensor, integrated stabilization).
Underwater Application
| For underwater photography, CMOS offers a decisive advantage: phase detection autofocus is directly on the sensor. Underwater, refraction distorts distances, making fast and precise autofocus essential for capturing moving subjects. | Characteristic | CCD (classic) | CMOS (modern) |
|---|---|---|---|
| Signal reading | Sequential | Parallel | |
| Speed | Slow | Very fast | |
| Power consumption | High | Low | |
| Cost | Higher | More accessible | |
| Video | Limited | 4K/8K native | |
| Use in 2026 | Scientific/medical | All devices |