Canon Patent Application: RF APS-C Mirrorless kit lens

I'm going to go out on a limb more than I usually do in classifying these APS-C mirrorless lenses because of the nature of this patent application.  Three reasons make me think this is an RF mount patent application;

1. All the lenses have a very relaxed back focus distance, far greater than the 18mm necessary for the EF-M mount.
2. While the back focus distance is rather large, it's not large enough for the EF-S mount. Also, the lens apertures are too slow for DSLR autofocus.
3. This patent application was submitted in 2019, well after the RF mount became the premier mount for mirrorless in Canon and also well after the EF-M mount had its kit lenses well developed.  Especially new kit lenses of hardly any redeeming quality.

There is no real reason for Canon to be researching a basic kit lens for the EF-M mount at this time, only for the RF mount.  It stands to reason that Canon would do some research in regards to the RF mount and APS-C just in case they do decide at a later date to make APS-C cameras and an ecosystem much like the EF mount.

The submitting of a patent application doesn't mean it's for certain coming, it simply means that Canon is covering their bases. This may never leave being just research and development.  However, it's curious that in subsequent weeks, we've discovered the core of a kit lens series, the normal zoom lens, and the telephoto lens - all very capable of being used on the RF mount.  

As with all patent applications, we caution that this is just a field of research, and evidence of a patent application does not necessarily mean there is going to be an actual product developed.

All these kit lenses are on the ultra-cheap side.  If you notice, they all rely on stretching the wide end of the lens image as their image height is all under 13.66mm on the wide end.  it appears because of the simplicity, while not mentioned, I would presume that these kit lenses are collapsable.

Canon RF-S 15-45mm F4-6.3

focal distance         15.46  24.00  43.65
F number                4.16   4.92   6.50
Half angle (°)         38.73  29.65  17.38
Image High             12.40  13.66  13.66
Total length of lens   96.84  85.69  84.27
BF                     26.19  34.03  49.18

Canon RF-S 18-45mm F4.5-6.3

focal length           18.53  30.00  43.65
F number                4.56   5.48   6.50
Half focal length (°)  33.78  24.48  17.38
Image height           12.40  13.66  13.66
Lens total length      89.11  81.23  81.40
BF                     28.48  38.21  47.77

Canon RF-S 16-45mm F4-6.3

focal length           16.41  24.00  43.65
F number                4.21   4.90   6.50
Half angle of view (°) 37.08  29.65  17.38
Image height           12.40  13.66  13.66
Lens total length      99.00  87.77  83.61
BF                     24.60  31.13  45.64

Canon RF-S 20-45mm F4-6.3

focal length           20.01  27.00  43.65
F number                4.60   5.15   6.50
Half angle of view (°) 31.79  26.84  17.38
Image height           12.40  13.66  13.66
Lens total length      92.00  84.32  83.15
BF                     33.77  39.37  52.69

Japan Patent Application 2021-086024

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