Focal length
Brandpuntsafstand · Lens & optics
The distance (in mm) between the optical centre of the lens and the sensor.
A short focal length (10-35mm) captures a wide scene: you see a lot of the surroundings. A long focal length (85-600mm) magnifies the subject and compresses space. 50mm is equivalent to what the human eye sees on a full-frame camera.
Tools that help with this: