"The third-generation of the internationally best-selling EF50mm f/1.8 series standard lens, the EF50mm f/1.8 STM, which has a body that includes a metallic mount, makes use of a stepping motor (STM) that ensures silent, speedy autofocus drive operation. The lens construction, consisting of 6 elements in 5 groups and a 7-blade circular aperture, has optimized lens coatings that suppress the occurrence of flare and ghosting, resulting in high image quality. With its lightweight, compact design that belies a surprisingly large diameter, this lens is convenient and easy to use for any scene, and allows for effortless taking of photos with a large, beautiful background blur. Max aperture: f/1.8 With STM motor Filter size: 49mm "