Key Features
EF-Mount Lens/Full-Frame Format
Aperture Range: f/2.8 to f/22
One Aspherical Element
Super Spectra Coating

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, benefitting both photo and video applications, an STM stepping AF motor is used to realize quick, accurate, and near-silent autofocus performance.

Short normal-length prime is designed for full-frame Canon EF-mount DSLRs, however can also be used with APS-C models where it provides a 64mm equivalent focal length.
Modestly bright f/2.8 maximum aperture benefits working in low-light, affords control over depth of field, and helps to keep the overall physical design compact and lightweight.
Pancake form factor measures less than 1" thick for an ultra-portable, versatile design.
One aspherical element limits distortion and spherical aberration in order to realize greater sharpness and accurate rendering.
Super Spectra coating has been applied to individual elements to minimize ghosting and flare for greater contrast and color neutrality when working in strong lighting conditions.
An STM stepping AF motor realizes smooth, near-silent autofocus that is complemented by a rear focus system, advanced AF algorithms, and a high-speed CPU for fast AF performance.
Rounded seven-blade diaphragm contributes to a pleasing out of focus quality that benefits the use of shallow depth of field and selective focus techniques.