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A Canon patent report describes a telephoto zoom designed with space inside the lens for an extender. In one reported example, inserting an approximately 1.4x extender changes the range from 103–294mm at f/2.91 to 143.99–411mm at f/4.10, while the stated overall length remains 370mm. These are patent-example figures, not specifications or test results for a released lens.
What the reported Canon patent describes
IMAGING PRESS reports that Japanese publication JP 2026-152979 describes a telephoto zoom optical design that reserves space toward the rear of the lens for an extender group. That arrangement differs from a conventional external teleconverter, which mounts between the camera and lens. The report says the light bundle is narrower in the reserved area, potentially allowing smaller extender glass; this is an explanation of the design rationale, not a demonstrated product result. IMAGING PRESS’s report on JP 2026-152979
The report’s principal example pairs a base zoom and an extender configuration with the same stated overall length:
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| Patent example configuration | Reported focal-length range | Reported maximum aperture | Reported overall length |
|---|---|---|---|
| Base zoom | 103–294mm | f/2.91 | 370mm |
| With extender inserted | 143.99–411mm | f/4.10 | 370mm |
These figures are attributed to patent examples by IMAGING PRESS (2026); they are optical-design figures, not measurements of a production lens. The report also lists other calculated examples with stated lengths of 360mm and 370mm, but they likewise should not be treated as product specifications. IMAGING PRESS’s summary of the example designs
#1 Best Overall
- This extender seamlessly attaches to select RF series lenses
- Increases the focal length by a factor of 1.4x
- Max focal length: 1.4
- Package Dimensions: 12.192 L x 18.542 H x 12.192 W (centimeters)
What the focal-length and aperture change means
The example’s range grows by approximately 1.4x at each end: 103mm becomes 143.99mm, and 294mm becomes 411mm. The aperture changes from f/2.91 to f/4.10, reflecting the light loss associated with increasing focal length through an extender. Canon’s educational guidance describes its RF and EF extenders as multiplying focal length by 1.4x or 2x while reducing lens speed. The patent example’s numbers are consistent with that general trade-off, but do not establish real-world exposure, autofocus, or image-quality performance for this design. Canon’s extender guidance
How this differs from existing Canon options
External teleconverters
Canon’s existing extenders attach to compatible lenses; compatibility is lens-specific. The report does not establish whether this patent design would use a standard Canon extender, which camera mount it might support, or whether any existing camera or lens could work with it. The concept described is an extender group housed within the lens rather than an accessory mounted externally.
Rank #2
- Dust- and water-resistant
- Increases the focal length by a factor of 2x
- Engineered with a combination of advanced optics, optimized coatings and high-quality construction
- Item Package Weight: 1.5 pounds
Canon’s earlier built-in extender lens
Canon has previously marketed the EF 200-400mm f/4L IS USM Extender 1.4x, a different telephoto zoom with a built-in, switchable 1.4x extender. It is a historical product comparison, not evidence that the reported patent will become a product. The sources do not establish its current availability. Canon EF 200-400mm f/4L IS USM Extender 1.4x
Drop-in filters are a separate feature
Canon also makes an EF-EOS R adapter with a drop-in-filter feature. That refers to a filter arrangement in an adapter, not the internal teleconverter optical design described in the patent report. Canon EF-EOS R adapter with drop-in filter
Rank #3
- Compatible with Select EF Mount Lenses. Note: This lens is only compatible with fixed focal length L-series lenses 135mm and over, as well as the EF 70-200/2.8L, EF 70-200/2.8L IS, EF 70-200/4L, and EF 100-400/4.5-5.6L
- 2.0x magnification factor
- 9 elements in 5 groups lens construction
- Spectra coating reduces ghosting/flare
Does the patent mean a new Canon lens is coming?
No product announcement is established by the patent report. It does not confirm a product name, retail price, shipping date, final specifications, or mount. The report is secondary coverage, and the official patent record and legal-status history were not available in the cited sources. Filing date, inventors, prosecution status, and the definitive scope of the claims therefore remain unverified. A patent describes a proposed design; it is not confirmation of commercial plans. IMAGING PRESS’s report
Performance details are also unknown: the sources do not establish weight, handling, autofocus behavior, image quality, or weather sealing. The numerical examples should be read only as reported patent calculations, not promises about a finished lens.
Quick Recap
Best Value
- 2.0X Teleconverter Extender Converter: The VILTROX C-AF 2X II auto focus 2.0X teleconverter expands the telephoto shooting range without increasing the number of lenses. It is especially suitable for users who want to use a telephoto lens to shoot wildlife, sports, etc.
- 4 Groups of 7 Optical Structures: The C-AF 2X II optical design takes full advantage of the performance of the main lens while minimizing the various aberrations that may occur when using the teleconverter. Even if the image is cropped, good rendering performance can be maintained.
- Autofocus: Compatible with Canon's high-performance autofocus technology, you can focus by pressing the shutter to get a fast and smooth focus experience. The anti-shake system on the camera body and main lens is still effective in helping users capture the decisive moment.
- EXIF Information Transmission: The magnification mirror is equipped with a microchip and exposed metal electronic contacts, which can realize data transmission between the lens, the magnification mirror, and the camera, and realize the compatibility between the lens and the camera.
- Compability: Designed for Canon EF mount telephoto lenses from 135mm to 600mm, including popular models like 70-200mm and 100-400mm.Compatible with various Canon DSLR camera bodies, including 5D Mark II, 80D, 760D, and 7D series.
Rank #4
- The 2X Teleconverter can make the focal length of all the Canon EF lenses increased to 2 times, Built-in 4 groups, 7 pcs optics, and the exposure factor enlarge approx 4. (equals to 2 aperture).
- Compatible for Canon EF Mount Lens.[Notice:It only compatible with fixed focal length L-series lenses 100mm and over, as well as the EF 70-200mm f/2.8L, EF 70-200mm f/2.8L IS, EF 70-200mm f/4L, and EF 100-400mm f/4.5-5.6L.]
- Support lens Auto Focus function.Outstanding image quality thanks to new optical design and improved AF performance. The focus speed is really fast and can track the subject, and lock the subject flexibly and accurately.
- Lens coatings are optimized to minimize ghosting and flare. With the aperture adjustment lever on the adapter, you can adjust the aperture fast.
- With an upgraded USB firmware interface, it supports USB firmware upgrading, and through subsequent upgrades, the adapter can improve its function, and fix bugs.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
