Highlights ef-mount lens/full-frame format aperture range: f/2.8 to f/22 one aspherical element super spectra coating stm stepping motor for smooth, silent af rounded 7-blade diaphragm features characterized by its slim, pancake design, the ef 40mm f/2.8 stm from canon is a sleek and versatile short-normal prime that is ideal for everyday, walk-around shooting. Its f/2.8 maximum aperture helps to realize its slim stature, and also suits working in difficult lighting conditions and offers control over depth of field for working with selective focus techniques. One aspherical element has been incorporated in the optical design, and helps to reduce distortion and spherical aberrations for high sharpness and clarity. A super spectra coating has also been applied, which helps to minimize lens flare and ghosting for improved contrast and color fidelity in strong lighting conditions. Additionally, when benefiting both photo and video applications, an stm stepping af motor is used.