Sony FE 100-400mm F4.5 GM OSS

The Sony FE 100-400mm F4.5 GM OSS is a super telephoto zoom for full frame Sony E-mount cameras. Sony announced it in May 2026 as the newest member of its G Master series. Unlike the older FE 100-400mm F4.5-5.6 GM OSS, it keeps a constant F4.5 aperture over the whole range, and Sony aims it at wildlife, bird, sports and photojournalism work.

Optical design

The lens has 28 elements in 20 groups. Sony lists a newly developed ED XA element, an XA element, two Super ED elements and three ED elements to control chromatic and spherical aberration. Nano AR Coating II is used against ghosting and flare, and an 11 blade circular diaphragm with controlled spherical aberration shapes the bokeh. The aperture runs from F4.5 to F32, and minimum focus distance is 64 cm with a maximum magnification of 0.25x. Sony says the lens resolves fine detail across the zoom range even wide open.

Autofocus and handling

Four XD linear motors, a floating focus mechanism and new algorithms drive autofocus. In Sony's own tests with the Alpha 9 III, autofocus is up to about 3 times faster and subject tracking about 50 % better than with the FE 100-400mm F4.5-5.6 GM OSS. The lens supports continuous shooting at up to 120 fps with AF/AE tracking on that body. Four focus hold buttons and a function ring can be customized. Built-in stabilization supports Active Mode and coordinated stabilization on compatible bodies, and the lens supports breathing compensation for video. The zoom is inner, so the length stays constant.

Build and size

The lens weighs 1,840 g, measures 119.8 mm in diameter and 328 mm in length and takes 95 mm filters, plus a 40.5 mm drop-in filter slot. Sony uses lightweight magnesium alloy parts and states a dust and moisture resistant design, not fully sealed, with a fluorine coat on the front element. Teleconverters extend the range to 800 mm, or to 1,200 mm equivalent in APS-C mode with the 2x converter.

Where it fits

The older FE 100-400mm F4.5-5.6 GM OSS, the model Sony compares it with, is lighter at 1,395 g but loses light at the long end. Sony's FE 200-600mm F5.6-6.3 G OSS and the FE 400-800mm F6.3-8 G OSS go further but are darker. The new FE 100-400mm F5.6-8 OSS is a much lighter and cheaper alternative with a slower aperture.

Pros and cons

Pros

• Constant F4.5 aperture from 100 to 400 mm
• Faster autofocus than the older GM, per Sony
• Inner zoom with constant length and stable balance
• Teleconverter support for 800 mm

Cons

• Heavier than the older GM (1,840 g versus 1,395 g)
• Large front filter (95 mm)
• G Master pricing tier

Verdict

The FE 100-400mm F4.5 GM OSS is aimed at professionals who want a bright, fast super telephoto zoom. It pays for the constant aperture with weight, so photographers who value light weight more than speed may prefer the older GM.