This portrait-length L-series prime is designed for full-frame Canon EF-mount DSLRs,however can also be used with APS-C models where it will provide a 136mm equivalent focal length. Notably fast f/1.4 maximum aperture offers extensive control over depth of field for working with selective focus techniques.This bright design also benefits working in low-light conditions. One glass-molded aspherical element helps to reduce distortion and spherical aberrations for improved sharpness and clarity. An Air Sphere Coating (ASC) has been applied to lens elements to reduce backlit flaring and ghosting for maintained light transmission and high contrast in strong lighting conditions. A ring-type Ultrasonic Motor (USM),along with optimized AF algorithms,is employed to deliver fast, precise,and near-silent autofocus performance. Optical image stabilization minimizes the effects of camera shake by compensating for up to four stops of shutter speed. Full-time manual focus operation is available for fine-tuning of your focus position when working in the AF mode. Fluorine coatings on the front and rear surfaces help reduce fingerprints and smudging. A weather-resistant design protects the lens from dust and moisture to enable its use in inclement conditions. Nine rounded diaphragm blades contribute to a pleasing out of focus quality that benefits the use of shallow depth of field and selective focus techniques.