Canon Patent: 28-45mm f/1.2 and 35-70mm f/1.4 Zoom Lenses With Reflective-Transmissive Elements

Canon just dropped a new patent, and it’s making us raise an eyebrow. Published February 27, 2026 (filed August 2024), the patent describes zoom lenses with apertures ranging from f/1.2 to f/1.4 — using reflective-transmissive (mirror) elements to keep things compact.

The Patent Details

The filing (P2026033938) covers several implementations:

• Example 2: 28-45mm f/1.2 — backfocus 0.40mm
• Example 3: 28.5-45mm f/1.4 — backfocus 0.40mm
• Example 5: 35-70mm f/1.4 — backfocus 0.70mm

Example 2

• Focal length: 28.00-45.00
• F-number: 1.20
• Half angle of view: 37.26-25.33
• Image height: 21.30
• Total length: 222.37-171.73
• Back focus: 0.40

Example 3

• Focal length: 28.50-45.00
• F-number: 1.40
• Half angle of view: 35.22-25.68
• Image height: 20.12-21.64
• Total length: 189.76-137.77
• Back focus: 0.40

Example 4

• Focal length: 15.40-36.01
• F-number: 1.42
• Half angle of view: 36.86-20.54
• Image height: 11.54-13.49
• Total length: 165.18
• Back focus: 0.40

Example 5

• Focal length: 35.70-68.00
• F-number: 1.40
• Half angle of view: 28.55-17.65
• Image height: 19.42-21.64
• Total length: 227.59
• Back focus: 0.70

That’s… extremely short backfocus. Like, “we’re not talking about RF mount” short.

Wait, What?

For context, RF-mount lenses need a backfocus of around 20mm+ to clear the mirror. These numbers — 0.40mm and 0.70mm — are barely enough to clear a sensor. This suggests the optical design is intended for:

• Compact cameras — where the lens sits directly on or very close to the sensor
• Surveillance cameras — where catching every photon matters more than shallow DoF
• Cinema sensors — some have extremely short flange distances

Not interchangeable lenses. Canon confirmed this in the filing notes: “backfocus is extremely short so this is not intended for interchangeable lens systems.”

But Here’s The Fun Part

Canon previously filed similar patents for prime lenses using the same reflective-transmissive technology — a 24mm f/0.7 and a 12mm f/1.0. Those were weird enough. Now they’re applying the same trick to zooms, going even wider and faster. A 28-45mm f/1.2 zoom would be absolutely enormous if built with conventional optics. The mirror elements fold the light path, dramatically shrinking total length.

Our Take

Is this coming to an RF-mount lens? Almost certainly not. The backfocus is physically incompatible.

Could this be a hint at future compact camera ambitions? Maybe. The G7 X line is due for a replacement, and a 28-45mm f/1.2 equivalent in a pocketable body would be something to see.

Or maybe Canon just likes filing patents for lenses they’ll never build. We’ve seen stranger things.

Source: Asobinet