Canon RF 50mm f/1.8 STM Lens Compact, lightweight, and close-focusing, the Canon RF 50mm f/1.8 STM is a sleek normal-length prime offering a classic, versatile field of view and an especially compact design. An ideal lens for every day, walkaround shooting, this 50mm f/1.8 is characterized by its bright design for available light shooting and apt depth of field control. The optical design incorporates one aspherical element, which reduces spherical aberrations and distortion, and also sports a Super Spectra coating to minimize flare and ghosting for improved contrast and color accuracy. Also, an STM motor affords impressively quiet and smooth autofocus performance and full-time manual focus override. Additionally, a configurable Control Ring lets you adjust exposure settings, including ISO, aperture, and exposure compensation, from the lens itself.