The constant f/2.8 aperture and 4-stop Vibration Reduction combine with an electromagnetic diaphragm for sharp, stable handheld shooting across the 24-70mm range. Advanced optics with aspherical and ED elements, plus weather sealing, deliver professional-grade image quality and durability in a versatile zoom. This lens is best for professional event and studio photographers who need reliable, fast autofocus and consistent exposure in demanding conditions.