Every other month, we come across patents that could result in the development of a new lens. Some are created for research purposes, while others tend to result in real lenses much later. There are other instances when you hear reports of launch dates, but they never truly materialize. An example is Canon RF 200-500mm f4L IS USM, which we have reported on since 2023, but there has been no official launch. But now, there are other articles that hint at the launch of another focal range that could rival Sigma.
According to Canon Rumors, sources have said that a new lens is on the horizon, which may be launched before the Canon RF 200-500mm f4L IS USM, the RF 300-600mm f/5.6L IS USM. While there have been patents of the 200-500mm before, the 300-600mm lens only has designs of vaiable apertures. In addition, there were also reports of a super-telephoto lens, with a constant aperture of f5.6. However, that has also not been seen yet.
Coming back to the Canon 300-600mm lens, no other specifications have been revealed yet. All we know is that the lens is going to release and that it will be lighter than Sigma. Sigma has already announced 300-600mm f/4 DG OS Sports, which is priced at $5999. However, it is only available for Sony E and Leica L mounts. It could be the case that a new Canon 300-600mm is likely to rival this in many ways. First off, the Canon L series‘ lens size and weight. With newer iterations, the company is making bigger lenses smaller and more compact. The Sigma 300-600mm weighs 3,985g for the L-mount, and so the Canon version could be around 2700g to 7500g.

There is also the aperture, which could make a huge difference. Canon already has RF 600mm f/4L IS USM, but the $13K price tag and the size make it impossible for some to buy or lug it around. In that regard, the Canon 300-600mm could fill in the gap, which is likely to be less than $13K but definitely more than $6K. The constant f5.6 aperture is a trade-off, but some would be far happy to do so.
In addition, there is speculation that Canon may also update its RF 400mm f/2.8L IS USM and RF 600mm f/4L IS USM with 1.4 teleconverters built-in. Both lenses were introduced in 2022, and it is possible that would like to make changes before the 2026 World Cup or the Olympics. For instance, in our test, the 600mm lens had less sharpness, while the 400mm faced a bit of paint wear-off.
Although the Canon 300-600mm is not an inexpensive lens, it is likely to be targeted at users, professionals, and high-end enthusiasts who need that extra bit of zoom range. With more companies focusing on telephoto lenses, it appears that Canon does not want to be left behind. And that is fair. A constant f5.6 aperture across the zoom range would be welcomed, but a lens that is also affordable would be a better direction for the company.
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