What Is Sensor Size and What Does It Mean When Talking About Photography?

In photography sensor size describes the physical dimensions of a sensor. Sensor size can be measured in mm or in inches, for example a ‘full frame’ sensor measures 36 x 24mm and a ‘micro four thirds’ or ‘4/3’ sensor measures 18 x 35mm. Sensor size relates to the physical dimensions of the sensor itself, not its imaging area. Sensor size can dramatically effect the overall quality of the output of a sensor, for example if we compare a full frame 20mp sensor with a 1″ 20mp sensor. The smaller dimensions of the 1″ sensor will require the use of much smaller pixels to achieve a resolution of 20mp, which will in turn result in decreased light sensitivity and increased susceptibility to noise. Conversely however larger sensors require larger bodies to house them, and larger lenses to cover their image area therefore impacting portability.