This compact, high-performance 35 mm full frame format mid-range zoom lens has been specifically designed bring out the full performance potential of the a7-series full frame E-mount bodies. True to the "Tessar" concept, the SEL2470Z offers superior sharpness and contrast in an ultra-compact lens design.A constant F4 maximum aperture throughout the zoom range allows the user to use optimum exposure parameters that will create the desired "look" at any focal length. The ability to use F4 at the telephoto end of the zoom range also reduces the need to use high ISO settings, and allows the use of high shutter speeds to capture action when necessary. A circular aperture design helps to deliver smooth background defocusing.