Leaked Sony FE 100-400mm f/4.5 GM lens hints at internal zoom redesign

Sony’s next 100-400mm may be less about chasing a brighter number and more about fixing the handling problems that matter in the field. Early leak images and specs point to a rumored FE 100-400mm f/4.5 GM II with internal zoom, a fixed-length body, and a more premium position in Sony’s telephoto lineup, exactly the kind of redesign that changes how a lens rides on a monopod, balances on a body, and seals up against dust and moisture.

That would mark a sharp shift from the current FE 100-400mm F4.5-5.6 GM OSS, which Sony officially introduced on April 19, 2017 as the first super-telephoto zoom in its flagship G Master series. The existing lens covers 100mm to 400mm with a variable f/4.5-5.6 aperture, an extending zoom barrel, a minimum focus distance of 0.98 meters, and a maximum magnification of 0.35x. Sony has pitched it as a fast, precise autofocus tool with professional-grade mobility, reliability, and operability for sports, wildlife, and similar subjects.

The rumored update suggests Sony sees room to improve the real-world experience, not just the optics. Internal zoom would keep the lens length constant through the range, a design that can make tracking birds in flight or following a sideline play feel steadier and less awkward than an extending barrel. It also hints at better weather resistance and a more balanced front-heavy feel, two traits that matter when a long lens spends hours outside.

Price could be the biggest test of patience. Current rumors place the new lens in the same neighborhood as Sony’s FE 50-150mm F2 GM, which launched around $3,899 to $3,999 depending on region. That would push the 100-400mm f/4.5 GM II firmly into prestige territory, and it is a reminder that Sony is not likely aiming this lens at casual buyers looking for a cheap reach upgrade.

Timing may also be close. Rumors point to a May 2026 announcement, possibly alongside the Sony a7R VI, and Sony Alpha Universe lists Alpha In Residence in New York City for May 14-15, 2026. If Sony uses that window to show the lens publicly, buyers deciding between the current 100-400mm GM and a possible replacement will have a very clear choice: buy now for a proven zoom, wait for the internal-zoom redesign, or ignore the premium jump entirely if the current lens already covers the job.