If Canon drops this lens next month, it'll mark a big step forward for RF shooters

November is shaping up to be a huge month for Canon. There are strong signs that we'll finally see the launch of the Canon EOS R6 Mark III, the follow-up to Canon's best-selling mirrorless camera, and four new Canon RF lenses: the RF 45mm f/1.2 STM, RF 20-50mm f/4 PZ, RF 24-70mm f/2.8L IS VCM and RF 300-600mm f/4-5.6L IS USM telephoto.

Among the rumored lenses, one in particular stands out: the Canon RF 300-600mm f/4-5.6L IS USM – an RF lens that many have been holding out for. If everything lines up, announcements could land on either November 16 or November 26, or possibly spread across both, as reported by Canon Rumors.

The Canon RF 300-600mm f/4-5.6L IS USM would fill one of the most glaring gaps in the RF lens lineup, and could end up being the lens to watch this year for wildlife, sport, event shooters or anyone who wants more flexibility at the long end. Add Canon's excellent IS and subject detection from newer bodies like the R5 Mark II or R6 Mark II, and this lens could become an essential part of a fast-moving, high-performance kit.

Where would the 300-600mm slot into Canon's current RF lineup?

For Canon RF users, the telephoto options have so far included the RF 100-500mm f/4.5-7.1L and the longer, consumer-priced RF 200-800mm F/6.3-9, announced last year. At the high end, there are the 600mm f/4L and 800mm f/5.6L primes – top-tier lenses in every way, except price and portability.

That leaves a big, obvious gap for a professional-grade zoom that balances range, speed and practicality.

That's exactly where the 300-600mm f/4.5-5.6L could land. If real, it would be the first RF lens to offer this specific range and aperture combination, with a fast f/4 at the short end and a still-very-usable f/5.6 at 600mm. In short, a flexible super-telephoto that doesn't compromise.

It's also a combination that isn't currently offered by Nikon, Sony or any other brand – making it all the more interesting. (For context: Nikon has the Z 180-600mm f/5.6-6.3, a well-priced option but slower and not part of the premium S-line. Sony's FE 200-600mm f/5.6-6.3 G OSS is hugely popular, but still not as fast or built to flagship specs.)

So, is it real?

Canon Rumors has rated the 300-600mm as "very likely," with multiple sources now pointing to November as the month it finally becomes official. It's still unconfirmed, but it's no longer just forum whistling – it's showing up alongside lenses that have appeared in official Canon marketing surveys.

If Canon really does drop this lens next month, it'll mark a big step forward for RF shooters – especially those who've been waiting for a zoom lens with serious reach, speed, and pro-grade construction.

Now, Canon – just say the word.

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