Canon Reportedly Working on an RF 300-600mm F/5.6L IS USM Super Telephoto Lens

Rumors surrounding Canon’s next big super telephoto release have been heating up, and it looks like the company might have something unexpected in the works. While many had been anticipating the RF 200-500mm F/4L IS USM, new information suggests Canon could be preparing an entirely different lens: the RF 300-600mm F/5.6L IS USM.

According to a report from Canon Rumors, sources familiar with the matter claim the upcoming lens will be priced “below $10,000” and could be noticeably lighter than Canon’s RF 400mm and 600mm prime lenses.

A Possible Rival to Sigma&rsrsquo;s 300-600mm F/4 DG OS Sports

Sigma recently introduced its 300-600mm F/4 DG OS Sports, priced at $6,599, and early impressions have been strong. If Canon’s rumored lens lands close to that price point — even with its slightly slower f/5.6 aperture — it could become a serious competitor.

Weight may play a key role here. The Sigma lens is a hefty 3.97 kg, making it less practical for handheld shooting. By going with an f/5.6 maximum aperture, Canon could keep the size and weight in check. Canon Rumors speculates the new RF lens could come closer to the RF 100-300mm F/2.8L IS USM, which comes in at a far more manageable 2.59 kg.

Canon RF 300-600mm f/5.6L IS USM, Here We Go Again – https://t.co/tFqmsBZRCU pic.twitter.com/VtEpDh5fXL

— Canon Rumors (@canonrumorsguy) August 22, 2025

Built-In Teleconverter or Separate Accessory?

There’s also speculation that Canon could consider adding a built-in 1.4x teleconverter, similar to what we’ve seen in the EF 200-400mm F/4L IS USM. That older lens offered added flexibility but came with a trade-off: a bulkier build and a weight of over 3 kg.

For this rumored RF 300-600mm, Canon might prioritize keeping things light and more compact. In that case, a separate teleconverter accessory would make more sense than integrating one directly into the lens design.

Will We See the RF 300-600mm Soon?

As of now, there’s no release window or patent filing tied to the RF 300-600mm F/5.6L IS USM, which usually signals that development is still in its early stages. If the reports are accurate, we may be looking at a 2026 release timeframe at the earliest.

Canon hasn’t confirmed anything yet, but if the rumors hold, the company could soon have a powerful and relatively portable super telephoto lens that slots neatly between its RF primes and third-party competitors.

We’ll be keeping an eye on this one and will update you as soon as more details surface. In the meantime, check out our in-depht review of the Sigma 300-600mm F/4 DG OS Sports.