The Canon RF 28-70mm f/2 L USM is a popular pro lens thanks to an unusually bright aperture – but a recent patent indicates that the optical engineers at Canon are exploring the possibility of an even longer f/2 zoom.
A recent patent published in Japan details a design for a compact, high-performance zoom lens that uses three or more focusing groups rather than the current RF series’ more typical two. Tucked in among the different patent drawings for potential lenses with such a design is a 70-200mm f/2 lens.
The patent, published in Japan on October 16 and first spotted by Canon Rumors , details a design that uses three focusing groups in order to create smaller zooms. While the patent isn’t specifically for one lens, the drawings reference a potential 70-200mm f/2 among even lenses like a 50-85mm f/1.4.
The challenge of making a bright zoom is making it small enough to carry at the same time. Reducing the size of a zoom means bringing optical groups closer to each other. The problem with that, the patent says, is that it leaves no room for the autofocus groups.
The patent hints that using “three or more” focus units could help shorten that distance, making it possible to create a bright zoom lens while avoiding a significant increase in size to get that brighter aperture.
The patent isn’t Canon’s first to reference using more than two focus groups. Another patent earlier this year from Canon explored using three focus groups to increase focusing performance.
Using more focus groups isn’t a completely new idea for Canon either – the company’s Dual Nano USM lenses use two autofocus motors. The newer VCM or Voice Coil lenses often pair the magnetic VCM system with a second smaller Nano USM autofocus motor, like with the Canon RF 35mm f/1.4L VCM.
The recent patent details several potential designs that could use three autofocus groups in order to create a brighter aperture without creating an overly heavy lens. But the possibility of a 70-200mm f/2 is drumming up a bit of excitement, considering how popular the 28-70mm f/2L USM lens is.
The Canon 28-70mm f/2L USM uses an ultrasonic autofocus motor and cuts some of the wide angle off of a more typical 24-70mm – but the lens is still notably heavier than the 24-70mm f/2.8L IS USM.
At 3.1 pounds / 1430g, Canon’s 28-70mm f/2L is actually heavier than the RF 70-200mm f/2.8L IS USM. That’s a perfect example of just how challenging making a reasonably sized 70-200mm with a bright f/2 would be.
Canon’s patents hint at what the company is working on behind the scenes – but the existence of a patent doesn’t guarantee that such a design will eventually become a real product. Canon often sets records for the number of patents filed in a year, which means many of them don’t become actual products. That leaves the concept of a 70-200mm f/2 zoom as wishful thinking and rumors, for now.
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