This fine lens delivers superb quality over a 100-400 mm range, extendable to 800 mm with an optional teleconverter. An ED XA (Extra-low Dispersion extreme aspherical) element plus XA, Super ED, and ED elements optimise chromatic and spherical aberration for high resolution throughout the zoom range. Maximum aperture is a constant F4.5 while zooming. The ED XA and XA elements contribute to exquisite G Master bokeh.

Advanced algorithms and four of Sony's XD (extreme dynamic) Linear Motors drive the floating focus groups for up to 3x faster AF. Tracking performance has been improved by up to 50%. With the α9 III body, reliable AF tracking is achieved at bursts of up to 120 fps. Focus breathing and zoom related focus and axial shifts are minimised for smooth, professional looking movie imagery.

Magnesium alloy parts and painstaking design have resulted in an overall weight of just 1,840 g. That is remarkably light for a super-telephoto zoom, allowing users to shoot long sessions with minimum fatigue. Inner zoom minimises centre-of-gravity shift when zooming, further enhancing handling and maneuverability. Even the zoom torque has been optimised to ensure smooth operation.

Optical stabilisation works with α in-body stabilisation to achieve outstanding results. A function ring can be assigned to control Preset Focus for quick registration and recall of a specific focus point, APS-C/Full Frame switching that allows quick shifts to the equivalent of 1.5x zoom, or Power Focus. A zoom smoothness switch and security slot are also provided.

In addition to a dust and moisture resistant overall design, the outer surface of the front element features a fluorine coating that prevents adhesion of fingerprints, dust, water, oil, and other contaminants. The coating also makes it easy to wipe the lens surface clean.