- Sony Alpha Rumors just published the first leaked image of an upcoming Sony FE 100-400mm f/4.5 GM — a constant-aperture telephoto that replaces the older f/4.5-5.6 variable-aperture 100-400mm GM OSS.
- Confirmed: internal zoom design (length doesn’t change while zooming, like the 200-600mm G), f/4.5 fixed aperture across the range — half a stop faster than the existing lens at the long end, and a stop faster at 400mm than competitors with variable apertures.
- Expected price: in the same tier as the 50-150mm f/2 GM ($3,899) — significantly more than the existing 100-400mm GM OSS (~$2,500). Announced for May 2026 alongside the rumoured Sony A7R VI.
- PhotoWorkout angle: this completes Sony’s constant-aperture telephoto progression (50-150 f/2, 70-200 f/2.8 II, 100-400 f/4.5, 200-600 f/5.6-6.3). The wildlife/sports buying decision now turns on whether you need 600mm reach — or whether 400mm at f/4.5 with the new GM build wins.
Sony Alpha Rumors just published the first leaked image of an upcoming Sony GM telephoto: the Sony FE 100-400mm f/4.5 GM. Not a refresh of the existing 100-400mm GM OSS — a different lens entirely, with a constant aperture, an internal zoom barrel, and a price tier that puts it next to the 50-150mm f/2 GM rather than alongside the original 100-400.
The leak surfaces about two weeks before Sony’s expected double-announcement in May 2026, where the lens is reportedly launching alongside the long-rumoured A7R VI 67-megapixel body. For wildlife and sports shooters, this is the most consequential Sony lens announcement of the year.
What’s Actually New About This Lens
The existing Sony FE 100-400mm f/4.5-5.6 GM OSS has been on shelves since 2017. It uses a telescoping zoom (the lens grows when you zoom out to 400mm) and a variable aperture that closes from f/4.5 at the wide end to f/5.6 at the long end. It is, by all accounts, an excellent lens — but it’s now eight years old, and the rest of Sony’s premium telephoto stack has moved on to internal-zoom, constant-aperture designs.
The new lens is the answer. Per Sony Alpha Rumors’ confirmed details:
- Constant f/4.5 aperture across the entire 100-400mm range — half a stop faster at the long end than the existing GM OSS, and a full stop faster than most variable-aperture competitors at 400mm.
- Internal zoom design — the lens does not change physical length when zooming. Same approach as the 200-600mm G OSS, which has been a wildlife favourite since 2019 specifically because of how predictable it handles on a gimbal or tripod.
- GM build — magnesium body, weather sealing in line with the rest of the G Master line.
- Price tier comparable to the 50-150mm f/2 GM ($3,899). Earlier whisper-numbers suggested ~$3,200; the latest leak revises higher.
- The aperture is f/4.5, not f/4 as one earlier leaker (HowToFly) had claimed. Sony Alpha Rumors corrected this in a later post.
Where It Sits in Sony’s Telephoto Lineup
Once this ships, Sony’s premium constant-aperture telephoto stack looks like a clean ladder of focal length, aperture, and price. Each lens covers a different shooter.
What’s notable is that Sony has now built the most complete constant-aperture telephoto progression of any full-frame mirrorless system — Canon’s RF stack still has gaps in the 100-400mm range, and Nikon’s Z line covers the same focal lengths but with fewer constant-aperture options at the long end. The 100-400mm f/4.5 GM is the lens that ties the room together.
For shooters who can’t wait two months, the existing Sony FE 100-400mm f/4.5-5.6 GM OSS is still on shelves at a meaningful discount to where the new lens is expected to land. Same focal range, same GM build, just the older variable-aperture design.
Sony FE 100-400mm f/4.5-5.6 GM OSS
Sony shooters who can’t wait until May for the constant-aperture refresh — the existing 100-400 GM OSS is still one of the sharpest telephoto zooms in the FE lineup
- Excellent optical performance — eight years on shelves and still the reference 100-400 for Sony
- Built-in Optical SteadyShot stabilisation, paired well with IBIS bodies
- Weather-sealed magnesium GM construction
- 1.4× and 2× teleconverter compatible — pushes effective range to 800mm at f/11
- Currently around $2,698 on Amazon — likely to soften further once the new GM ships in May
- Variable f/4.5-5.6 aperture — the new GM is constant f/4.5 (half a stop faster at 400mm)
- Telescoping zoom design (lens grows when zoomed out) — the new GM is internal zoom
- Older AF actuator generation than the latest Sony GM lenses
- About to be the older lens in Sony’s stack — resale value will likely drop after May
The existing 100-400mm GM OSS is the sensible buy if you need the lens this month and 400mm reach without the new GM’s price premium. At $2,698 it’s $1,000+ cheaper than what the new f/4.5 GM is expected to launch at, and the optical performance is still excellent. The catch: you’ll be living with the older variable aperture and telescoping zoom design while the rest of the world moves to constant-aperture, internal-zoom telephotos. If you can wait two months, do.
Wildlife and Sports: 100-400 GM, or 200-600 G?
The buying question this lens forces is sharper than it sounds. Both lenses use internal zoom; both will be GM/G-tier sharp; both target the same shooter. The difference is reach versus light.
The 200-600mm G ($2,000) is heavier (2,115 g vs. an estimated ~1,500–1,700 g for the new lens), reaches further, and costs roughly half as much. It’s variable-aperture (f/5.6-6.3) so you lose nearly a stop of light at the long end. For pure birding or any sport where 600mm matters more than maximum aperture — football from the sidelines, motorsport, distant wildlife — the 200-600 keeps making sense.
The new 100-400mm f/4.5 GM is the better choice if 400mm covers your subject and you’d rather have the constant aperture (faster shutter speeds in low light, cleaner background separation, predictable exposure across the range). Birds in flight at golden hour, indoor gymnastics, BMX in cloudy conditions — anywhere the light gets thin — the constant f/4.5 will earn its premium.
The other tradeoff is body size and travel weight. An internal-zoom 400mm with a constant aperture should be markedly smaller than the 200-600, which makes it the better pick if you fly to your subjects. The 70-200 f/2.8 GM II made similar gains over the original by going internal-zoom; the same playbook here would be a meaningful change for shooters who pack glass into carry-on.
Why the May Double-Announcement Matters
Sony has been quiet on full-frame body launches for almost two years — the A7C R was the last real release, and the A7R V is now four years deep. The A7R VI rumours suggest a 67-megapixel sensor, a refreshed body, and most likely the same processor refresh that’s been threaded through the A1 II and A9 III.
Bundling a new GM telephoto with a flagship resolution body is the same playbook Sony used when the A7R IV launched in 2019 alongside the 200-600mm G — the camera and the lens reinforce each other in coverage. A 67-megapixel sensor benefits from a constant-aperture telephoto more than a typical 24-megapixel sensor would, because the resolution lets shooters crop in past 400mm without losing detail. The two announcements together signal Sony reasserting itself in the wildlife and sports segments where Canon’s R5 II and R1 have taken some mindshare back.
FAQ
When will the Sony 100-400mm f/4.5 GM be officially announced?
Sony Alpha Rumors expects an announcement in May 2026, alongside the long-rumoured A7R VI. A specific announcement date has not been confirmed by Sony, and the leaked image was not accompanied by an official press release.
Is this a replacement for the existing Sony FE 100-400mm f/4.5-5.6 GM OSS?
Effectively, yes. Sony has not announced whether the older GM OSS will be discontinued, but the new lens overlaps its focal range with a faster constant aperture, an internal-zoom design, and a higher price point. Expect the older lens to remain available for a while at clearance pricing — and to become the budget-friendly long telephoto option in the lineup.
How much will it cost?
Sony Alpha Rumors’ latest source places the price in the same tier as the 50-150mm f/2 GM ($3,899). Earlier sources whispered closer to $3,200; the higher figure is the more recent leak. Final pricing will be confirmed at announcement. Expect $3,800–$4,000 USD.
Does it have OSS image stabilisation?
Not yet confirmed in the leaks. The existing 100-400mm GM OSS has built-in optical stabilisation, and most Sony telephotos in this focal range carry it. Whether the new lens will use OSS or rely entirely on in-body stabilisation from the A7R VI remains unclear until Sony’s announcement.
Should wildlife and sports shooters wait for it?
If you already own the 200-600mm G and rarely need wider than 200mm, no — your kit is fine. If you’ve been shopping the existing 100-400mm GM OSS and don’t need the lens this month, waiting until late May for the official announcement is worth it. Pricing on the older lens will likely soften once the new one ships, and the new lens itself is the better tool for any shooter who values constant aperture, internal zoom, and the latest GM build over the older variable-aperture design.
The Bottom Line
The leaked Sony 100-400mm f/4.5 GM is exactly the lens the Sony telephoto stack has been missing: a modern, constant-aperture, internal-zoom GM in the most-used wildlife/sports range. Bundled with the A7R VI in May, the announcement positions Sony to reclaim some of the high-resolution wildlife mindshare Canon’s been picking up. The price will sting — north of $3,800 puts it firmly in pro-tier territory — but for shooters who’d otherwise be looking at a 600mm f/4 prime at $13,000, the value calculus is clear.
We’ll update this post with confirmed specs, sample images, and pricing as soon as Sony’s announcement lands.
Image credit: All editorial graphics by PhotoWorkout. Lens specifications and leak details via Sony Alpha Rumors; pricing references via B&H Photo Video.
Primary Leak Coverage
- Sony Alpha Rumors — First leaked image of the new Sony 100-400mm f/4.5 GM lens – The leaked image and confirmation of the new lens
- Sony Alpha Rumors — Internal zoom and higher price – Confirms internal-zoom design and ~$3,900 price tier
- Sony Alpha Rumors — First exclusive info about the new 100-400mm f/4.5 GM – Original Sony Alpha Rumors story breaking the lens
Lineup Reference
- Sony — FE 200-600mm F5.6-6.3 G OSS official product page – Existing internal-zoom telephoto reference
- B&H — Sony FE 50-150mm f/2 GM – Price-tier reference for the new 100-400 GM ($3,899)
- B&H — Sony FE 70-200mm f/2.8 GM OSS II – Adjacent constant-aperture telephoto in the lineup ($2,800)
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