Capturing a bird in flight or a fast-break on a basketball court usually requires a combination of patience, precise timing, and a level of technical mastery that takes years to develop. However, spending time with the new Sony 100-400mm f/4.5 GM paired with the A7R VI suggests that the barrier to entry for high-end wildlife and sports photography is dropping significantly.
The synergy between this glass and the camera’s 66MP resolution transforms the shooting experience into what feels like “straightforward mode.” For a street photographer accustomed to shorter focal lengths, the ability to nail a sharp shot of a distant subject without a deep background in ornithology is a testament to how far autofocus and sensor density have evolved.
The Sony 100-400mm f/4.5 GM is positioned as a bridge between enthusiast gear and the brand’s most expensive professional cinema and sports glass. It currently retails for €5,000 / £4,400, a price point that reflects its professional aspirations and the inclusion of a constant aperture—a significant departure from its predecessors.
Engineering for the Field
At first glance, the 100-400mm f/4.5 GM might seem like a simple iteration of the FE 100-400mm F4.5-5.6 GM OSS released in 2017. In reality, the shift to a constant aperture is a fundamental change in how the lens handles light and depth of field across its entire zoom range.
Sony designers reportedly weighed the choice between an f/4 and an f/4.5 constant aperture. The decision to land on f/4.5 was driven by weight savings. At 1,840g, the lens remains a substantial piece of equipment, but it is surprisingly manageable for a telephoto of this reach. Given the efficiency of modern BSI (back-illuminated) full-frame sensors, the half-stop difference is a negligible trade-off for the reduced physical strain during a long day of field work.
The lens barrel is thoughtfully equipped with customizable FN buttons, allowing photographers to adjust key settings without taking their eye off the viewfinder. The inclusion of support for 45mm drop-in filters at the base is a practical victory; it eliminates the need for expensive and cumbersome 95mm front filters, which are often impractical on long telephoto lenses.
The 66MP Advantage and Cropping Potential
While the lens provides the reach, the A7R VI provides the flexibility. The 66MP sensor allows for an aggressive cropping strategy that effectively extends the lens’s reach far beyond 400mm. In practice, this means a photographer can capture a wide shot and crop in significantly—well beyond a standard APS-C crop—while still maintaining enough detail for a high-quality print.
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This is where the constant f/4.5 aperture becomes a strategic asset. Even at the 400mm end, the lens maintains a level of background separation that creates a professional, creamy aesthetic. While the bokeh can occasionally become “busy” depending on the background, it is noticeably smoother than the f/5.6 limit of the 2017 model.
| Feature | 2017 FE 100-400mm GM | New FE 100-400mm GM |
|---|---|---|
| Aperture | f/4.5-5.6 (Variable) | f/4.5 (Constant) |
| Weight | Approx. 1,395g | 1,840g |
| AF Performance | Standard GM | Enhanced Tracking |
| Filter System | Front Filter | 45mm Drop-in Support |
Autofocus and Real-World Tracking
The true strength of this pairing is the autofocus acquisition. Even when compared to high-end G Master primes, the 100-400mm f/4.5 holds its own. While a prime like the FE 50mm f/1.2 GM is inherently faster due to its simpler optical path, the 100-400mm is surprisingly close in responsiveness.
During tests on a busy basketball court, the lens excelled in tracking human subjects. Utilizing the A7R VI’s human-priority focus mode, the system locked onto faces and tracked rapid movement across the court with minimal hunting. The result is a high “hit rate” for shots that would typically be lost to slight focus misses.
For those who are not professional birders or sports photographers, this combination removes the technical anxiety of the shot. The equipment handles the heavy lifting of tracking and resolution, leaving the photographer to focus on composition and timing.
While a full technical assessment of chromatic aberration and low-light distortion is still required, the initial hands-on experience suggests a potent tool for anyone needing serious reach without the bulk of a prime super-telephoto. Users looking for more information on the Sony Alpha ecosystem can find official specifications and compatibility charts on Sony’s professional portals.
The next step for this hardware will be long-term field testing in varied lighting conditions to determine how the f/4.5 aperture holds up in deep twilight and high-contrast environments.
Do you think a constant aperture justifies the price jump for telephoto zooms? Share your thoughts in the comments below.
