Sony FE 100-400mm F4.5 GM OSS Announced – Constant F4.5 Aperture, Internal Zoom, and Four XD Linear Motors

Lens News

by Johnnie BehiriMay 13^th, 2026

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Sony has unveiled the FE 100-400mm F4.5 GM OSS, a G Master telephoto zoom built around a constant F4.5 aperture across the entire focal range, an internal zoom design, and four XD Linear Motors driving a floating focus system. The new lens sits alongside the existing 2017-vintage FE 100-400mm F4.5-5.6 GM rather than replacing it, occupying a previously empty slot in Sony’s super-telephoto lineup.

The announcement arrives at the same event that introduced the new Alpha 7R VI, and the two products are clearly designed to work together. Sony is positioning the new lens as “the first 100-400mm with no professional compromise,” with the constant F4.5 aperture replacing the original lens’s F4.5-5.6 variable design. The original FE 100-400mm F4.5-5.6 GM OSS became one of the most popular telephoto zooms in the Sony system after its 2017 release, and Sony’s updated lineup chart still keeps it in the Enthusiast and Amateur zoom tier alongside the FE 200-600mm F5.6-6.3 G and the FE 400-800mm F6.3-8 G. The new F4.5 GM moves up one tier into a hybrid Professional/Enthusiast position that has been empty until now.

What constant F4.5 actually changes

Across the 100 to 400mm zoom range, the new lens stays at F4.5. For comparison, the original FE 100-400mm f/4.5-5.6 lens hits F5.6 at the telephoto end, the Sony FE 200-600mm lens arrives at F6.3, and the FE 400-800mm lens stops down to F8.0. At 400mm, the new lens is therefore one stop brighter than the original 100-400 GM, roughly 1.3 stops brighter than the 200-600mm lens at the same focal length, and a full two stops brighter than the 400-800 lens.

For video work, the practical implication is more significant than the stop count suggests. Variable-aperture zooms force an exposure shift mid-move whenever the focal length changes, which either requires manual ISO ramping or auto-exposure compensation that introduces visible brightness pumping. A constant aperture eliminates that problem entirely, which is one reason cinema lens designs almost universally avoid variable apertures. The same logic applies to stills shooters working in shutter-priority modes, where a 2/3-stop aperture shift during a burst on the original 100-400 GM previously meant adjusting ISO mid-sequence or losing shutter speed at the long end.

A new optical formula with 28 elements

The lens uses 20 groups, 28 elements (including one filter), built around a more aggressive special-element count than the original. Sony has specified two Super ED glass elements, three ED glass elements, one XA extreme aspherical element, and one new ED XA element that combines extra-low dispersion with the extreme aspherical surface. The original SEL100400GM, by contrast, used one Super ED and two ED elements, with no XA or ED XA elements.

The ED XA element is the genuinely new piece of glass here. XA elements are manufactured to sub-0.01-micron surface precision and are specifically chosen to suppress onion-ring bokeh, an artifact where surface unevenness on conventional aspherical lenses shows up as concentric rings inside defocused highlights. Combining that surface precision with extra-low dispersion in a single element should, in principle, suppress chromatic aberration and spherical aberration simultaneously without introducing the onion-ring problem that XA elements are designed to solve. Sony also says each lens is individually fine-tuned during manufacturing to maximize bokeh quality, beyond design-level aberration control.

Surface coatings include Nano AR II for flare and ghosting suppression, plus a fluorine coating on the front element to resist contamination. The aperture is built from 11 blades arranged in a circular pattern for smoother ball bokeh.

The internal zoom is the most video-relevant change

For cinematographers, the internal zoom design is arguably the most consequential decision in this lens. The original SEL100400GM was an extending zoom, with the physical length growing from 205mm at 100mm to 289.6mm at 400mm. The new lens stays fixed at 328mm / 12.91 in throughout the zoom range.

Internal zoom matters for several practical reasons in motion work. If you insist on working with this lens on a gimbal, the balance will not shift during a zoom move, which means a one-time balance setup holds across the entire focal range. The lens does not pump air in and out of the barrel as it zooms, reducing dust ingress risk in field conditions. Weight distribution stays constant for handheld operators. And the barrel does not extend into subjects or surrounding obstacles, which matters in press boxes, wildlife blinds, and other space-constrained shooting positions. Sony has also added a zoom smoothness switch with two settings, Smooth and Tight, that adjust the zoom ring torque. The Smooth setting is positioned for tracking fast-moving subjects, while Tight is for fixed-composition work where the operator needs the ring to hold position firmly.

Four XD Linear Motors and Sony’s autofocus claims

The new lens drives its floating focus system with four XD Linear Motors, which Sony says have been redesigned to deliver significantly higher thrust than previous generations. Sony’s published performance claims compared to the original SEL100400GM are an autofocus speed improvement of up to 3x and approximately 50 percent better tracking performance, measured under Sony’s own test conditions with the lens held at a fixed focal length. The lens supports up to 120 fps autofocus tracking and continuous shooting when paired with the Alpha 9 III, and 30 fps tracking on the Alpha 7R VI.

As with all manufacturer-supplied performance figures, both the 3x speed claim and the +50% tracking claim need to be verified in real-world use.

Size and weight, and what Sony chose to sacrifice

The new lens measures 119.8 x 328mm / 4.72 x 12.91 in and weighs approximately 1,840g / 64.9 oz. Compared to the original SEL100400GM, which measures 93.9 x 205mm / 3.70 x 8.07 in (minimum length, extending to 289.6mm) at 1,395g / 49.2 oz, that is a substantial step up. The new lens is roughly 26mm wider, 39mm longer at minimum, and 445g heavier than its predecessor. Some of that comes from the constant F4.5 aperture, which requires more glass at the long end. Some comes from the internal zoom mechanism, which adds bulk in exchange for the fixed barrel length. And some comes from the more aggressive special-element count.

For context against Sony’s other super-telephoto zooms, the new lens is actually more compact than the FE 200-600mm F5.6-6.3 G, which measures 111.5 x 318mm at 2,115g, despite the new lens having a similar diameter and length. It is also over 50 percent lighter than the older A-mount Sony 200-400mm f/4 G SSM with the 1.4x extender attached (3,620g). Sony’s framing is that the new lens represents the lightest professional-grade 100-400 constant-aperture option, which is technically true, although it is also the heaviest 100-400 in the Sony lineup by some margin.

Professional-grade operational controls

The control layout is shared with the SEL300F28GM (300mm f/2.8 GM), suggesting Sony intends the new 100-400 to slot directly into pro telephoto kits. On the right side of the barrel, the lens has four focus-hold buttons distributed around the circumference, a function ring, a zoom ring, a focusing ring marked LR MF, and a row of five control switches: focus mode, full-time DMF, focus-range limiter (specified for infinity to 4m), SteadyShot on/off, and SteadyShot mode. The tripod collar locking knob, security slot, and drop-in filter slot all sit on the right as well. On the left side are the zoom smoothness switch and the tripod collar ring-clicking select switch, with strap holes on both sides.

The function ring offers three assignable modes via the camera menu. The default is Power Focus, where rotating the ring right or left moves focus toward infinity or close range, respectively. The second mode is Full Frame / APS-C S35 toggling, where any rotation switches the angle of view between full frame and the Super 35 crop, useful on high-resolution bodies like the Alpha 7R VI or Alpha 1 II for instant additional reach. The third mode is Preset Focus, where the operator can register a specific focus and zoom position by holding the ring, and recall it instantly with a flick.

Built for fixed installations as well as field work

Beyond the standard G Master sealing, the lens includes two features clearly aimed at professional fixed-installation use. A built-in security slot in the tripod collar area accepts a third-party security wire (not supplied), enabling asset protection in press centers, stadiums, studios, and remote shooting locations. Sony notes this is the same security slot specification as on its recent G Master super-telephoto primes. The fluorine front element coating resists contamination and simplifies cleaning when the lens is mounted outdoors for extended periods.

The lens is rated dust and moisture-resistant, with seals on all buttons and rings, though Sony explicitly notes it is not guaranteed to be 100 percent dust or moisture-proof. The tripod foot provides both a 1/4-inch and a 3/8-inch mounting hole. Supplied accessories include a lens hood, a strap, and a lens case.

Teleconverter compatibility extends reach to 800mm

The lens is compatible with both the Sony SEL14TC 1.4x and SEL20TC 2.0x teleconverters. With the 1.4x attached, the effective focal range becomes 140-560mm, and with the 2.0x it becomes 200-800mm. Sony specifically claims that “full G Master quality is maintained when the teleconverters are in use,” which is a notable assertion given that teleconverters typically introduce measurable optical degradation. This is one of the claims that will need verification once the lens reaches reviewers.

With the 2x converter attached, the new lens effectively covers the focal range that previously required the FE 200-600mm F5.6-6.3 G or the FE 400-800mm F6.3-8 G, which is part of why Sony has placed it in a tier above those zooms in the lineup chart.

Pricing and availability

The Sony FE 100-400mm F4.5 GM OSS will set you back $4,298 (€4,567.44), and we will update this article when its availability time is defined.

Does Sony’s first constant F4.5 telephoto zoom move the 100-400 category forward enough to justify carrying an extra 445g over the original? Don’t hesitate to let us know in the comments below!