The FE 28-70mm F2.8 GM, attached to the newly-announced a1 II. Photo: Mitchell Clark

Sony has announced the FE 28-70mm F2 GM, a zoom lens that trades 4mm at the wide end for an aperture that's a stop brighter than the one found on a classic 24-70mm F2.8. It's the company's first constant F2 zoom lens for its E-mount cameras.

The lens's optical formula consists of 20 elements in 14 groups, with three aspherical lenses, three super ED elements, and one ED element. It uses an 11-blade aperture. The front element has an oil and water-resistant flourine coating, and the lens is moisture and dust resistant.

It's far from a compact lens, though it's not as monstrously large as you might expect – it weighs in at 918g (32 oz) and is around 140mm (5.5") long. It has an 86mm filter thread.

Sony makes it obvious what lens it's competing with; highlighting that it's 36% lighter and 11% smaller in diameter than Canon's RF 28-70mm F2 L lens while claiming better corner-to-corner sharpness. The company also says the lens's four linear motors can focus even when shooting at 120fps, and emphasized that they're quieter than the older ring-type ultrasonic style motor in the Canon F2. In fairness, that lens was one of the original RF-mount releases, announced in 2018.

"Sony makes it obvious which lens it's competing with"

The quieter operation should help when shooting video. Other pluses for video: it has an internal focusing mechanism which should make it easier to use the lens on a gimbal, the ability to switch the aperture ring into clickless mode and supports the focus breathing compensation mode included on some Sony bodies. You can also set the manual focus ring to have a linear response, which should make focus pulls easier.

The lens has a variety of switches and buttons. There are two customizable focus hold buttons, an Iris lock switch, the aperture click switch and a zoom smoothness switch that lets you adjust between "smooth" and "tight" torque settings.

It's not the fastest zoom lens available for E-mount: at the time of writing, that prize goes to Sigma's 28-45mm F1.8, though that model has substantially less reach on the tele end and only a 1/3EV increase in light-gathering ability.

The FE 28-70mm F2 GM will be available in mid-December and has an MSRP of $2,899.

Sony FE 28-70mm F2 GM Specifications