35mm camera equivalent
From The Glossary of Digital Photography
Refers to a viewing angle on a digital camera that is the same as the angle one would see using a certain focal-length lens on a 35mm camera. Different digital cameras use different sized digital sensors, which affect the viewing angle using the same lens. For example, some digital cameras have a 1.5 factor, which means that using a 50 mm lens on such a camera would have the same viewing angle as a 75 mm lens on a 35mm film camera. Using that same lens on a digital camera with a full-size sensor would make the viewing angle equal to a 50 mm lens on a 35mm film camera.
