Sony FE 100-400mm f/4 GM II: A Review of the 2026 Lens
April 2, 2026
Quick Summary: The Sony FE 100-400mm f/4 GM II is one of three new lenses Sony plans to release in 2026. Unlike the current f/4.5-5.6 model, the new version will feature a constant f/4 aperture throughout the zoom range, making it particularly appealing for wildlife and sports photography. The release is expected before mid-2026.
The photography community has been abuzz with rumors about three new Sony lenses for months. Among them, the FE 100-400mm f/4 GM II—an updated version of the popular super-telephoto zoom with variable aperture—has attracted particular attention.
But how well-founded are these expectations? And what is known about the new lens so far?
What is known about the Sony FE 100-400mm f/4 GM II
According to information from SonyAlphaRumors, the company is developing three new lenses for full-frame FE-mount cameras. Among them:
100-400mm f/4.0 GM (constant aperture)
100-400mm G (variable aperture)
16-28mm f/2.0 GM
The key difference between the GM II and the current SEL100400GM is its constant f/4 aperture throughout the entire focal length range. The current model has a variable aperture of f/4.5-5.6.
This is a significant improvement. A constant f/4 aperture means stable exposure when zooming and more effective autofocus in low light.
Choose your shooting equipment and order it from JustBuy
After a review, you usually want to move on to the next step: looking at real options, comparing specifications, and understanding what you can buy without a lot of searching. JustBuy is an online tech store featuring cameras, laptops, smartphones, audio equipment, accessories, and other devices for work, photography, and everyday use. Here you can immediately check availability, price, delivery, payment, and warranty terms.
Looking for where to view and buy equipment?
At JustBuy you can:
View current models and their specifications
Compare devices and choose the right option
Check availability, price, delivery, and warranty
Place an order online or get advice before purchasing
👉 Contact JustBuy to select equipment and clarify the terms of purchase.
Comparison with the current SEL100400GM
The current Sony FE 100-400mm f/4.5-5.6 GM OSS has been available since 2017. According to the authoritative resource Dustin Abbott, this lens demonstrates outstanding sharpness and fast autofocus, making it a popular choice for sports and wildlife photography.
In his 2020 review, Phillip Reeve noted that the SEL100400GM has a reputation for sharpness and fast autofocus. According to the source, the lens retails for approximately €2,500 new in Europe, or just under €2,000 used.
Here's a comparison of known specifications:
According to Sony's official specifications on www.sony.ru, the current model has a filter diameter of 77mm and dimensions of 94x205mm. The new version may be larger due to its constant f/4 aperture.
Why a constant f/4 aperture is important
The difference between f/4.5-5.6 and f/4 may seem small on paper, but in practice, it's a significant advantage.
First, a constant aperture ensures a consistent amount of light across the entire zoom range. When shooting at 400mm with f/4, the photographer receives two-thirds of a stop more light than at f/5.6. In low-light conditions—at a stadium in the evening or in a forest at dawn—this is critical.
Second, the autofocus system performs more effectively with a faster aperture. The Sony Alpha 9 III, as mentioned on Alpha Universe, is used by professionals with fast lenses, including telephoto lenses.
Competition and Market Situation
Sony isn't the only company offering lenses in the 100-400mm range. Dustin Abbott noted in his review that there is competition from numerous telephoto lens manufacturers in the same range.
Sony's main competitor is the FE 200-600mm f/5.6-6.3 G OSS. This lens is less expensive and offers a longer zoom range, but is significantly heavier and slower.
Sony's 2026 telephoto lens lineup
For wildlife and sports photographers, compactness and fast aperture are often more important than maximum focal length. That's why the 100-400mm f/4 may be the perfect balance.
When to Expect Announcement and Release
According to SonyAlphaRumors, the company is highly likely to introduce three new lenses by mid-2026. A specific announcement date has not yet been confirmed.
The release could take place later in 2026, possibly in the spring or summer. Sony's typical cycle is an announcement followed by availability 1-2 months later.
What does this mean for photographers?
For those who specialize in wildlife, sports, or reportage photography, the arrival of the 100-400mm f/4 GM II could be a significant upgrade. Advantages of a constant f/4 aperture:
Steady exposure when zooming
More efficient autofocus
Better performance in low light
More beautiful bokeh at wide apertures
Of course, there are potential trade-offs. A lens with a constant f/4 aperture will inevitably be heavier and more expensive than a variable aperture model.
The Reddit community is actively discussing these rumors, and many photographers are willing to accept the added weight for the benefits of a constant aperture.
Alternatives in the Sony Lineup
If the 100-400mm f/4 GM II proves too expensive or heavy, Sony will presumably also release a variable aperture version—the 100-400mm G (not GM). This model will offer a more affordable alternative for enthusiasts.
Furthermore, Sony already has the FE 400mm f/2.8 GM OSS—a flagship super-telephoto prime lens. According to Sony's official website, this lens offers outstanding speed, G Master resolution, and professional reliability, but is significantly heavier and more expensive.
Frequently Asked Questions
When will the Sony FE 100-400mm f/4 GM II be released?
The exact date is not confirmed, but sources suggest a release by mid-2026. The announcement may happen in spring or summer 2026.
How much will the new lens cost?
The official price has not been announced. Considering the current f/4.5-5.6 model costs around €2500, the constant f/4 version may cost €3000–3500 or more.
What is the difference between f/4 and f/4.5-5.6?
A constant f/4 aperture provides the same light across all focal lengths. A variable f/4.5-5.6 means that at 400mm the aperture drops to f/5.6, losing about 2/3 of a stop of light.
Will the lens be compatible with older Sony Alpha cameras?
Yes, all FE lenses are compatible with full-frame Sony E-mount cameras, including A7, A9, and A1 series. It also works with APS-C cameras.
How will GM II differ from the current GM model?
The main difference is the constant f/4 aperture instead of f/4.5-5.6. Improvements in optics, coatings, and autofocus speed are also expected.
Should you buy the current model or wait for the new one?
If constant aperture is critical — it’s worth waiting. If f/4.5-5.6 is enough and you need a lens now — the current SEL100400GM remains a great choice.
What other lenses is Sony planning for 2026?
Rumors suggest Sony is also working on a 100-400mm G with variable aperture and a wide-angle zoom 16-28mm f/2.0 GM.
Conclusion
The Sony FE 100-400mm f/4 GM II promises to be one of the most significant releases of 2026 for photographers specializing in telephoto lenses. Its constant f/4 aperture addresses the main limitation of the current model and takes the lens to a new level of versatility.
While exact specifications, price, and release date have not yet been officially confirmed, rumors from reliable sources indicate a high probability of an announcement in the coming months.
Stay tuned to Sony's official website and reputable resources like SonyAlphaRumors and Alpha Universe for updates.