A fascinating new Japanese patent application from Canon, JP 2026-167867 (filed April 2, 2025, and published just days ago on October 15, 2026), reveals that Canon is actively working on a massive leap forward for fast, ultra-bright telephoto primes.

By utilizing a revolutionary, next-generation ultra-high-index optical glass (with a refractive index (n_d) reaching an astonishing 2.2 to 2.3), Canon aims to overcome the traditional hurdle of massive, heavy glass elements. This tech has the potential to dramatically shrink the size, weight, and aberrations of wide-aperture lenses.

Among the optical formulas detailed in the patent, two exciting standouts have caught our eye: a Canon RF 100mm f/1.4 full-frame prime and a compact Canon RF-S 65mm f/1.4 APS-C prime. Here is a breakdown of what this could mean for the RF and RF-S systems.

The Breakthrough: Ultra-High-Index Glass

Historically, large-aperture portrait and telephoto primes (like the legendary f/1.2 and f/1.4 lenses) require massive, bulbous front elements to bend light efficiently without producing severe spherical and chromatic aberrations.

Patent JP 2026-167867 focuses on leveraging newly developed high-refractive glass formulations to resolve this. By using materials with an extremely high refractive index (exceeding 2.2), light is bent much more aggressively over a shorter distance.

For photographers, this translates directly to:

• A major reduction in lens length and diameter.
• Shedding substantial weight, making hefty portrait lenses much more handheld-friendly.
• Superior optical performance, by correcting field curvature and spherical aberrations right at the front groups.

RF 100mm f/1.4 (Full Frame)

While Canon’s portrait lineup is already spearheaded by the magnificent RF 85mm f/1.2L and the RF 135mm f/1.8L, there has always been a coveted spot for a fast 100mm.

A 100mm f/1.4 using this high-index glass could bring the dream of telephoto “f/1.2-like” background separation into a much more compact, practical form factor.

Rumors have already circulated about Canon potentially filling the f/1.4 gap with VCM (Voice Coil Motor) hybrid primes. Integrating this newly patented high-index optical formula could yield an ultra-compact RF 100mm f/1.4L VCM that outperforms larger lenses while remaining remarkably lightweight.

RF-S 65mm f/1.4 APS-C (104mm Equivalent)

Perhaps even more exciting for a vast portion of the community is the 65mm f/1.4 APS-C (RF-S) formula.

On Canon’s APS-C bodies (like the EOS R7, R10, and R50), a 65mm focal length has a 1.6x crop factor, giving it a 104mm full-frame equivalent field of view.

• A True “Holy Grail” Portrait Lens for APS-C: Currently, the RF-S lineup is heavily dominated by slower variable-aperture zooms. An RF-S 65mm f/1.4 would instantly become the premier choice for natural, ultra-shallow-depth-of-field portraiture on crop-sensor bodies.
• Ultra-Compact Form: Thanks to the high-index glass, Canon can keep this fast f/1.4 prime tiny, matching the compact footprint and balanced handling that APS-C shooters require.

When Will We See These?

As always with patents, we have to treat this as a glimpse of Canon’s R&D focus rather than a guaranteed product release on next week’s schedule. However, with Canon actively building out its fast prime family and standardizing hybrid VCM autofocus systems, the push for compact, ultra-fast optics is incredibly high. Finding ways to bypass the physical weight limits of standard glass is the key to the future of the RF mount.

Would a compact RF 100mm f/1.4 or an RF-S 65mm f/1.4 find a spot in your gear bag? Let us know in the comments!

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via j-platpat