A flat lens, ideal for travel and street photography. Its advanced optical design ensures excellent image quality, while a large f / 2.8 maximum aperture enables handheld shooting in low light. STM focus provides smooth, almost silent autofocus when shooting movies.A fast maximum aperture of f / 2.8 provides plenty of light so you can shoot in dark shooting conditions without the use of flash. It's perfect for creating shallow depth of field effects so you can isolate your subject against a soft, unfocused background.