Sony FE 100-400mm f4.5 OSS GM Lens

What’s new?

The Sony FE 100–400mm f4.5 G Master introduces a series of engineering updates that improve resolution, autofocus response and exposure consistency across the zoom range. The revised optical design introduces Super ED, ED, ED XA and XA elements to reduce chromatic and spherical aberrations more effectively and maintain contrast towards the edges of the frame, particularly at longer focal lengths. Four XD Linear Motors replace the previous drive system, increasing autofocus speed by up to three times and improving tracking accuracy by approximately 50%*, while also supporting high-frame-rate AF tracking. A constant f4.5 aperture eliminates exposure shifts when zooming, keeping shutter speed and depth of field consistent during reframing.

Operational changes offer greater handling stability and control speed. The internal zoom mechanism keeps the lens length fixed, maintaining balance and reducing dust intake when adjusting focal length. A new function ring provides direct access to focus control, format switching, and preset recall, allowing direct adjustments without leaving your shooting position. Combined with improved bokeh rendering, rear drop-in filter support and expanded physical controls, these changes provide more consistent handling and faster response for a more cohesive shooting experience.

*when used with the A9 III under Sony test conditions with a fixed zoom

Optical design and image quality

The lens features a refined 28-element construction arranged into 20 groups, including two Super ED elements, three ED elements, one ED XA element and one XA element. This combination reduces chromatic and spherical aberrations across the zoom range, maintaining resolution from centre to corner at both wide and telephoto positions. Sony has also applied the Nano AR Coating II to reduce internal reflections, lowering flare and ghosting when shooting into strong light. This coating helps maintain contrast and detail in backlit scenes and at longer focal lengths where contrast typically drops.

The upgraded 11-blade circular aperture maintains a rounded iris shape as it stops down, producing uniform defocused highlights. XA elements reduce onion-ring effects in out-of-focus areas, resulting in smoother tonal transitions. This optical behaviour produces consistent background separation when isolating distant subjects, particularly in wildlife and sports photography, when you can’t get closer to your subject.

Aperture and exposure

Arguably the most important upgrade for a telephoto zoom, the aperture is now fixed at f4.5 throughout the 100–400mm zoom range. This upgrade removes exposure variation when changing focal length, allowing shutter speed and ISO to remain fixed during reframing. Depth-of-field characteristics also remain consistent, maintaining the same subject separation across the zoom range. This technology allows continuous shooting without frequent exposure adjustments when zooming.

Autofocus and stabilisation

With four XD Linear Motors now driving a floating focus system, multiple focus groups move independently to increase focus speed while maintaining positional accuracy during continuous tracking. The floating design also reduces aberrations at close focusing distances, improving image quality when working nearer to the subject. Thanks to this design, users experience more reliable autofocus acquisition and retention when tracking subjects with unpredictable movement.

High-frame-rate autofocus tracking is supported when paired with compatible Alpha bodies, maintaining focus accuracy during continuous bursts. Optical SteadyShot stabilisation compensates for camera shake at long focal lengths, with Active mode increasing correction during movement. In practice, these features reduce frame-to-frame movement when shooting handheld and help maintain consistent framing without external support.

Design and operation

The internal zoom mechanism keeps the lens length constant during focal length changes, maintaining a consistent centre of gravity and improving balance when shooting handheld or when mounted. It also reduces the likelihood of drawing dust into the lens compared to extending zoom designs, supporting more stable handling over time. Users can also adjust zoom torque with a switch for smooth or tight settings. Smooth mode enables rapid focal-length changes when tracking movement, while tight mode increases resistance to prevent unintended zooming.

A programmable function ring provides direct access to Power Focus, APS-C switching and preset focus recall, allowing direct adjustments without navigating camera menus. Additional external controls include multiple focus-hold buttons, a focus range limiter, stabilisation switches and full-time DMF, with controls placed for easy access whether shooting horizontally or vertically.

Build and durability

The lens features a dust- and moisture-resistant construction with sealing around buttons and rings. While it’s not 100% dust- and moisture-proof, the seal significantly reduces the likelihood of dust or moisture entering the lens during outdoor use. A fluorine coating on the front element also repels water, oil and dirt, allowing contaminants to be removed more easily without affecting the surface. For added outdoor security, Sony has also included a built-in security slot, allowing users to tether the lens in fixed positions for remote or unattended setups.

Despite its extended reach, this telephoto lens is relatively compact at approximately 1,840g, weighing less than both the 200–600mm class and traditional 200–400mm f4 models. The internal zoom structure avoids extension, keeping the centre of gravity stable and reducing mechanical wear over time. This combination of weight and fixed length supports longer handheld use with less fatigue.

What’s in the box?

• 1 x Sony FE 100-400mm f4.5 GM OSS Lens
• 1 x Lens Hood ALC-SH187
• 1 x Lens Front Cap ALC-F95S
• 1 x Lens Rear Cap ALC-R1EM
• 1 x Soft Case
• 1 x Lens Strap
• 1 x Case Strap
• 1 x Slot-in Filter