The sensor is the part of the digital camera that captures light to create an image. It is analogous to the film in non-digital cameras. Similar to the coating of light-sensitive material on photographic film, the sensor of a digital camera has light-sensitive cells. In this tutorial we will teach you everything you need to know about this important component.

Although there are technical and design differences in digital camera sensors, they all operate on the same basic principles. A sensor has millions of light-sensitive cells or photodiodes on a wafer of silicon. Each of these generates an electrical charge when struck by a particle of light that enters the camera through the lens. A colored filter produces the proper coloration. Then the camera’s processing turns these electrical charges into an image which is then stored on the camera’s memory or storage card. Each photodiode creates one pixel in the final image. This is where the term megapixel comes from. Pixels are the small pieces of information created by light-sensitive photodiodes. Millions of pixels are combined to create an image.

There are two main types of camera sensors: CCD (Charge Coupled Device) and CMOS (Complimentary Metal-Oxide Semiconductor). There are involved technical differences, including the circuitry design, but both perform the same function. The CMOS processors are easier and more cost effective to produce in larger sizes, so they are often used in larger SLR (Single Lens Reflex) cameras. CMOS processors also use less power, so they are commonly used in mobile phones. Most compact point-and-shoot cameras and camcorders use the more common CCD sensor.

Several other sensor types are also available, but they are much less popular. The Foveon X3, is a newer chip that is actually a type of CMOS sensor with a special color processing. It is currently only being used in some Sigma and Polaroid Cameras. Fujifilm also produces some of their cameras with a special sensor called the Super CCD. This is a conventional CCD with individual photocells that are arranged in a diagonal honeycomb pattern rather than the horizontal/vertical grid pattern used in most sensors.