Canon has published a new patent outlining a series of prime lenses for full-frame cameras which, if released, I believe will see the camera giant hone in on creating more compact, quiet autofocus lenses.
Patent number P2026059152 was published by the Japan Patent Office on April 07. The patent details designs for several lenses that use an inner-focusing system where the front and back elements don't move, but the middle group does.
The Google-translated document says that the goal is to create "a compact optical system capable of focusing with suppressed aberration fluctations." Abberations, such as colored fringing, can change with settings like aperture, so the patent hints at a lens that focuses on consistently controlling those imperfections in a compact size.
The patent details several potential focus lengths for the design, including a 55mm f/1.8, an 85mm f/1.8, and a 131mm f/2.
What’s interesting is that, while Canon currently does not offer any of these exact prime focal length/aperture combinations within its RF arsenal, it does already have the RF 85mm F1.2L USM and RF 135mm f/1.8L IS USM, albeit these lenses feature an ultrasonic motor (USM), which is generally better for stills.
Canon also has the VCM series, which includes the RF 85mm f/1.4 L VCM, and uses the Voice Coil Motors. But, patents for L-series lenses don't often pop up before the actual announcement, Canon Rumors notes.
The way that the patent describes an internal focusing system makes me think of quieter lenses designed for video. Canon's USM lenses are designed for high-speed autofocus, and optical elements need to move quickly to achieve this. While great for photographing stills, the clunkier and noisier mechanism isn’t ideal for video.
Autofocus driven by a voice coil motor (VCM) is a better alternative for producing videos, as the newer technology locks on to subjects near instantaneously and almost silently.
VCM autofocus is sometimes paired with a Nano USM – an optimized form of traditional USM autofocus – to move different lens groups independently not only quickly, but also smoothly.
Of course, there’s also the possibility that Canon patented at least some of these designs with a view of simply stopping competitors beating it to the punch; considering Canon released the RF 85mm f/1.4L VCM just last year, you could make a strong case for this.
That said, Canon officials recently confirmed the manufacturer plans on continuing to release six to eight RF lenses per year for the foreseeable future.
And with the RF ecosystem already flush with prime lenses featuring stepping-motor-driven autofocus, I see Canon potentially differentiating the patented lenses with VCMs.
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