Sony FE 100-400mm f/4.5 GM OSS

The Sony FE 100-400mm f/4.5 GM OSS is a full-frame Sony E-mount telephoto zoom with a constant f/4.5 aperture across the whole 100–400mm range. Sony announced it in May 2026 as the successor to the FE 100-400mm f/4.5-5.6 GM OSS. It zooms internally, so the length never changes, and four XD Linear Motors make autofocus up to 3x faster than its predecessor. It also has an 11-blade circular aperture, optical image stabilisation and a dust- and moisture-resistant build.

Key Specifications

• Focal length: 100–400mm (full frame)
• Maximum aperture: f/4.5, constant across the zoom range
• Minimum aperture: f/32
• Lens construction: 28 elements in 20 groups (ED XA, XA, 2 Super ED and 3 ED elements)
• Aperture blades: 11 (circular)
• Image stabilisation: Yes (OSS — Optical SteadyShot)
• Autofocus: 4 XD Linear Motors, floating internal focus
• Minimum focus distance: 0.64–1.5m | Max. magnification: 0.25x
• Filters: 95mm front, 40.5mm drop-in
• Zoom: internal, the length stays the same
• Weather sealing: dust and moisture resistant
• Weight: 1840g | Length: 32.8cm | Diameter: 119.8mm
• Lens mount: Sony E cameras (full-frame FE)
• Teleconverters: Sony 1.4x (SEL14TC) and 2x (SEL20TC)

How does it differ from the f/4.5-5.6 version?

The FE 100-400mm f/4.5-5.6 GM OSS from 2017 closes down to f/5.6 at 400mm and gets longer as you zoom. The new f/4.5 GM keeps f/4.5 at 400mm, which gives you two-thirds of a stop more light right where you need it most. Because it zooms internally, the balance doesn't shift on a gimbal or monopod, and it doesn't pull in dust while you zoom. The trade-off is size: at 1840g and 32.8cm it is clearly bigger than the 1395g original, and it takes 95mm front filters.

Who is it for?

Wildlife, birds in flight, motorsport and field sports: anywhere your subject moves fast and the light is dropping. Paired with a fast Sony full-frame body such as the Alpha 1 II or Alpha 9 III, the tracking autofocus and constant f/4.5 really come into their own. With Sony's 1.4x teleconverter you get 140–560mm at f/6.3, and with the 2x you get 200–800mm at f/9.