Most digital compact cameras have non-interchangeable zoom lenses which have been designed to work with a specific sensor size. Some prosumer models allow to extend the zoom range via converters. Because of the small sensor sizes, the lenses used in digital compact cameras have to be of much higher optical quality than glass which would be "acceptable" on a 35mm camera. This is less of an issue with digital SLRs with because their sensors are much larger.

Typical sensor size of 3, 4, and 5 megapixel digital compact cameras	Typical sensor size of 6 megapixel digital SLRs

See also focal length.