Range-finder wide angle
Lenses designed for range-finder cameras, such as the Leica M Bessa, r Zeiss Ikon, generally offer superior quality to those for SLR cameras because the optical design can be made symmetrical.
DSLR wide angle
A modern design that is usually compact for a wide-angle lens for SLR cameras, the lens offers the equivalent of a 30mm lens’s field of view.
4/3 format wide angle
This very fast 25mm (37mm equivalent) optic with f/1.4 maximum aperture is typical of the new generation of compact high-performance lenses for small digital SLR cameras.
Adapted from Fundamentals of Photography by Tom Ang (Alfred A. Knopf, 2008; $25)