The EF40mm f/2.8 STM comes in an ultra-compact and lightweight design, with a diameter of 68.2mm, a thickness of 22.8mm and weighing 130g making it the slimmest and lightest EF lens produced. A fast f/2.8 aperture, 7-blade circular aperture and aspherical lens elements let the lens achieve a high level of image quality from centre to corner.