Full-frame G Master standard zoom lensThe ultimate choice for professional portrait, travel and event photographers seeking the highest possible optical performance. The XA element reduces aberration and delivers the ultimate resolution throughout the entire zoom range and aperture range, as well as from corner to corner of all image files.Designed to achieve 50 line pairs/mm resolving powerIt is not easy to achieve spatial frequency of 50 lines pairs per millimeter at a lens's widest aperture, but that is Sony's baseline for G Master design. Unprecedented resolution and other demanding design parameters yield outstanding reproduction of the most detailed subjects and scenes with superior contrast throughout every frame. G Master resolution is simply the highest in its class.Previously unattainable surface precisionBuilt with three aspherical elements including a newly developed and essential ingredient for astonishing resolution - is a new XA (extreme aspherical) lens element with better that 0.01-micron surface precision. The extremely precise XA element reduces aberration and delivers the ultimate resolution throughout the entire zoom range and aperture range, as well as from corner to corner of all image files.Constant F2.8 max aperture maintains exposure and depth of fieldConstant F2.8 max aperture maintains exposure and depth of field regardless of the focal range you choose to zoom to. When changing yo