Canon Patent: 70-200mm F4 IS And APS-C 18-50mm F4 IS

A new Canon patent application, published on May 29, 2025, offers a peek into some potentially exciting new lenses. It outlines a few optical designs that closely resemble a “70-200mm F4” and an “APS-C 18-50mm F4”, both seemingly inner zoom lenses, meaning their physical length stays constant while zooming.

Patent Overview

• Publication Number: P2025082363
• Publication Date: 2025-05-29
• Title: Zoom Lens and Imaging Device
• Filing Date: 2023-11-17
• Applicant: Canon Inc. (ID: 000001007)
• Summary: The patent describes a compact, lightweight, positive-lead-type zoom lens design, optimized to correct various aberrations even at longer telephoto focal lengths.

Example Designs

Example 1 (Likely full-frame 70-200mm F4)

• Focal Length: 73.68–194.48mm
• Aperture: F4.10
• Half Angle of View: 16.36°–6.35°
• Image Height: 21.64mm
• Total Length: 198.01mm
• Back Focus: 49.13–65.78mm

Example 2 (Likely APS-C 18-50mm F4)

• Focal Length: 18.54–52.02mm
• Aperture: F4.10
• Half Angle of View: 33.06°–14.50°
• Image Height: 13.66mm
• Total Length: 130.47mm
• Back Focus: 14.72mm (constant)

Both examples maintain a consistent lens length while zooming, which is classic inner zoom behavior. This could be a move targeting video shooters, especially given the growing demand for compact, stable optics. It’s also possible this research influenced the development of lenses like the RF-S 14-30mm F4-6.3 IS STM PZ, which was also patented around the same timeframe.

So, is Canon working on an inner zoom 70-200mm F4? Technically, the RF70-200mm F4 L IS USM already exists, so launching another F4 zoom in the same range might seem redundant. But with the newer RF70-200mm F2.8 L IS USM Z in the mix, maybe we’re looking at a slimmed-down F4 version of that. It wouldn’t be out of character for Canon to double down if they see a niche worth filling.

[via asobinet]