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Could a Canon RF 300mm f/2.8L be on the way for mirrorless bodies?

Could a Canon RF 300mm f/2.8L be on the way for mirrorless bodies?
(Image credit: Future)

A Canon RF 300mm f/2.8L lens could be on the way to Canon's full-frame mirrorless systems, bolstering the ever-growing lineup of premium telephoto optics for the EOS R ecosystem. 

Back in October 2020 we reported on the rumored 2021 roadmap for RF mount glass. No less than eight telephoto lenses were listed, including a Canon RF 100-400mm f/5.6-7.1 IS USM and Canon RF 400mm f/2.8L IS USM optics. And now it appears that a Canon RF 300mm f/2.8L can be added to that list, if the latest patent filing by the manufacturer is anything to go by.

• Read more: Best Canon RF lenses

A new patent, discovered by Northlight Images, reveals that the Canon RF 300mm f/2.8L IS USM will have a total length of 274.19mm. Intriguingly, the existing DSLR version, the Canon EF 300mm f/2.8L IS USM II is actually a little shorter at 248mm. That means the new RF variety could be around 10% longer. 

This is a little odd, as the manufacturer's recent RF versions of EF telephotos (such as the Canon RF 70-200mm f/4L IS USM) are both shorter and lighter than their DSLR counterparts. Perhaps there will be a good reason for this, such as implementing new technology, though we're eager to find out if the lens will be heavier as well.

Image stabilization

Canon's EF 300mm f/2.8L IS II USM for DSLRs (Image credit: Canon)

We'd expect the image stabilization (IS) system to feature the same 5-stop, 3-mode system seen on the EF version (with one mode for general shooting, a second for panning shots, and a third that only engages the IS when the shot is being taken, which can work better for erratic subjects and also saves battery life). 

The obvious benefit of the new RF version would be to the ability to use the lens IS in conjunction with the in-body image stabilization featured in the Canon EOS R5 and Canon EOS R6. This combination IS can deliver up to 8 stops of stabilization, and would certainly be very welcome (especially on the rumored Canon EOS R1).

Compatibility with RF teleconverters?

(Image credit: Canon)

We'd expect the Canon RF Extender 1.4x and Canon RFExtender 2x teleconverters to be compatible with such an impressive optic. However, this hasn't been a given with Canon's recent telephotos. 

These teleconverters have a protruding front element, which requires a recession in the back of the lens. The shorter flange distance of the RF mount and the compact design of lenses like the Canon RF 70-200mm f/2.8 IS USM meant that the RF Extenders wouldn't physically fit – much to the chagrin of many users.

It will be interesting to see if Canon design this optic with compatibility in mind, as the ability to extend the 300mm f/2.8 to 420mm f/4 or 600mm f/8 (with the 1.4x and 2x extenders respectively) would be very handy indeed.

And the price?

As for the price, well, the current Canon EF 300mm f/2.8L IS II USM costs $6,099 / £6,069. However, we've seen a premium attached to Canon's mirrorless optics so we would expect the price to be higher than its EF counterpart – how much higher will depend on the technology and features included, as well as any expensive lens elements and coatings.

We've seen this happen with lenses like the Canon RF 85mm f1.2L USM, which costs $2,699 / £2,799 while the Canon EF 85mm f1.2 L II USM for DSLRs is considerably more affordable at $1,799 / £1,999. 

That being said, the RF 85mm f/1.2 is one of the sharpest lenses we've ever used – so the price premium is arguably justified. Only time will tell if the Canon RF 300mm f/2.8L will also follow the same line – and with the 2021 Tokyo Olympic Games on the horizon, we could be hearing more very soon.

Read more:

Best Canon telephoto lenses
Best telephoto lenses
Canon RF 85mm f/1.2L IS USM review
Canon RF 85mm f/1.2L IS USM DS review