In this patent application (2024-099414), Canon is showing off some interesting embodiments to some inner zoom / inner focus lenses for both full frame and crop cameras.
The half-image heights are smaller for both full frame and APS-C and curiously, for all focal lengths. Usually, we see image circle manipulation on the wide end and that disappears as you increase the focal length. Still, this is a “hold my beer” moment for optical design and image circle stretching.
Canon’s goal with these lenses is to facilitate rapid zooming in a compact lens size and is also equipped with a power zoom feature. Could there be a series of kit lenses with power zoom? Other manufacturers have done it – and it would be nice if Canon would as well (especially if the zoom feature could be controlled via USB / tethered operation). That R100 webcam could use a sledgehammer power zoom kit lens.
Canon sets up the patent application with this summary;
In recent years, there has been a demand for zoom lenses that are wide-angle, compact, and high-performance (high resolution). Furthermore, in recent years, there has been an increase in demand for moving images, and in order to achieve smooth zooming operations, there is a demand for zoom lenses with an electric zoom function.
Canon RF-S 14-30mm F4-6.3
| Wide | Medium | Telephoto | |
| Focal length | 14.40 | 21.16 | 29.10 |
| F-number | 4.10 | 5.18 | 6.26 |
| Half Angle of View | 43.6 | 32.8 | 25.3 |
| Half Image height | 11.51 | 12.52 | 12.90 |
| Total Lens Length | 78.75 | 78.75 | 78.75 |
| Back Focus Distance | 11.50 | 11.50 | 11.50 |
Canon RF 24-50mm F4-6.3
This is similar to the already existing Canon RF 24-50mm F4-6.3 IS STM but with a different optical formula and inner zoom. It’s a little longer to support inner zooming (80mm) compared to the collapsed size of the Canon RF 24-50mm F4-6.3 IS STM (58mm).
| Wide | Medium | Telephoto | |
| Focal length | 24.70 | 35.00 | 48.50 |
| F-number | 4.10 | 5.07 | 6.14 |
| Half Angle of View | 41.5 | 31.6 | 24.0 |
| Half Image height | 18.19 | 19.77 | 20.62 |
| Total Lens Length | 107.48 | 107.48 | 107.48 |
| Back Focus Distance | 20.26 | 20.26 | 20.26 |
Canon RF-S 12-28mm F4-6.3
This is an “in-between” optic that wouldn’t be ultra-wide and wouldn’t be a normal zoom as this would be equivalent to 20-45mm on a full frame. I’m not sure how useful it would be, but it’s an interesting idea nonetheless.
| Wide | Medium | Telephoto | |
| Focal length | 12.36 | 20.00 | 27.16 |
| F-number | 4.10 | 5.40 | 6.40 |
| Half Angle of View | 47.9 | 34.1 | 26.2 |
| Half Image height | 10.67 | 12.26 | 12.59 |
| Total Lens Length | 79.81 | 79.81 | 79.81 |
| Back Focus Distance | 11.50 | 11.50 | 11.50 |
As with all patent applications, this is merely a look into Canon’s research and may not end up in an actual product. What this does, is give us a glimpse into Canon’s research.
Japan Patent Application 2024-099414
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much of Canon's assembly is automated these days.