Olympus 50mm f/2.0 Telephoto Macro ED Lens for Olympus Digital SLR Cameras Specially treated to shed water droplets, and engineered to withstand the rigorous demands of professional use Designed to capitalize on the design advantages of the OLYMPUS Four Thirds System Large f/2.0 aperture, with minimum weight and bulk 50mm range -- equivalent to 100mm in conventional 35mm photography For use with the OLYMPUS E-1 and other Four Thirds Series Digital SLR Cameras, as specified