crop factor

Crop factor describes how a camera's image sensor size compares to a standard 35mm film frame. A smaller sensor, common in many digital cameras, captures a narrower field of view with the same lens. This means that a lens appears more "zoomed-in" on a crop sensor than on a full-frame sensor. The crop factor is a number (like 1.5 or 1.6) that tells you how much smaller the sensor is relative to 35mm film. For example, a 50mm lens on a crop sensor with a 1.5 crop factor gives a viewing angle similar to a 75mm lens on a full-frame camera.