Image showing Camera Lens Settings

Lenses for crop sensor – DX (Nikon) EF-S (Canon)
Lenses for Full Frame – FX (Nikon) EF (Canon)

Focal length is measured in millimetres for example 18mm, 50mm, 200mm.

Prime lenses have a fixed Focal length
Zoom lenses have a variable Focal length

A standard Focal length is 50 mm on full frame cameras and 35mm on APS crop sensors cameras.

Below the standard Focal length is classed as wide angle
Above the standard Focal length is classed as telephoto

Because of the difference in sensor sizes, APS-C and Micro 4/3rds cameras have smaller sensors and therefore lens focal lengths will be 1.6x for APS-C and 2x for Micro 4/3rds

Most cameras come with a kit lens that is around 24-70mm for Full Frame or 17-35mm for crop sensors