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I just have one statement for this patent application (2026-003099), Canon, please, just:
Do it
With the Canon EOS R7 Mark II on the horizon, the zoom with a fast aperture but around the focal lengths necessary for a crop camera would not only be welcomed, but really, it’s necessary. Someone was commenting to me that they miss the Canon EF-S 15-85mm on the RF mount, so here you go, I hope your wishes come true.
This is Canon’s second attempt at this patent application, as they released it previously as well, back in May of 2025. Meaning that Canon is still attempting to get this patent application through the process.
Canon doesn’t say much about the designs, except,
To provide a compact, wide-angle zoom lens that is robust against manufacturing errors and yet offers high optical performance.
There are three embodiments that I’ll focus on because they start at 15mm, which, for Canon’s APS-C crop cameras, is, in my opinion, the optimum focal length for a normal zoom.
Canon RF-S 15-70mm f/4 IS STM
A constant f/4 zoom for Canon’s APS-C system is long overdue. Granted, it’s not the same as the Canon EF 17-55mm f/2.8, but starting at 15mm would be a delicious standard zoom, giving Canon’s APS-C users their 24-105mm equivalent focal length lens.
The lens does take a bit of a stretch hit at 15mm, which isn’t unusual for Canon’s RF non-L designs, but that cleans up before the midpoint of 36mm. The back focus distance of 10.46mm is pretty tight. I’m not sure if we’ve seen a production example of a lens that sits 9.5mm back into the lens mount on a Canon RF camera. The shutter assembly is usually quite close to the sensor plane, so I really don’t think this is a problem, but it’s certainly an extreme example of sitting inside the mount.
| Wide Angle | Middle | Telephoto | |
|---|---|---|---|
| Focal length | 15.45 | 36.03 | 67.94 |
| F-number | 4.12 | 4.12 | 4.12 |
| Half angle of view (°) | 41.27 | 19.59 | 10.60 |
| Image height | 12.66 | 13.66 | 13.66 |
| Lens length | 100.14 | 108.00 | 120.23 |
| Back Focus Distance | 10.46 | 10.79 | 12.37 |
Canon RF-S 15-70mm f/2.8-4 IS STM
This design makes me go back and forth on whether or not I like the preceding design better or this one. Having a maximum aperture of f/2.8 on the wide end is extremely compelling, even if there is a gradual slowing down of the lens past the midpoint of 36mm.
This lens still needs some stretching at its wide angle, but that quickly disappears before the mid-point of the lens, where the image circle is the full size required for Canon’s APS-C sensors (13.66mm). This lens does have an odd movement, with the rear element starting off at 8.5mm inset into the mount, and then increasing to 10mm inset into the mount before moving back out at the telephoto end. This could make it a no-go as it sits even closer to the sensor plane than the preceding example.
| Wide Angle | Middle | Telephoto | |
|---|---|---|---|
| Focal length | 15.45 | 36.47 | 68.05 |
| F-number | 2.88 | 3.81 | 4.12 |
| Half angle of view (°) | 41.28 | 19.17 | 10.42 |
| Image height | 12.66 | 13.66 | 13.66 |
| Lens length | 100.14 | 108.00 | 120.23 |
| Back Focus Distance | 11.46 | 9.98 | 13.02 |
Canon RF-S 15-80mm f/2.8-5.6
After drooling over the prior designs, Canon also introduces a potentially less exciting embodiment, but one that I think would have the greatest chance of getting created of the three.
As with the other designs, the wide-angle requires some stretching from 12.66mm to 13.66mm, but that also goes away by the time you reach the midpoint of the zoom at 36mm.
This zoom is also a little longer than the zooms, making it closer to a better “EF-S 15-85mm”. As well, the back focus distance is where I think is more realistic for a lens on the RF mount, sitting in the mount less than 8mm.
| Wide Angle | Middle | Telephoto | |
|---|---|---|---|
| Focal length | 15.45 | 36.29 | 83.77 |
| F-number | 2.88 | 4.00 | 5.80 |
| Half angle of view (°) | 41.36 | 19.65 | 8.71 |
| Image height | 12.66 | 13.66 | 13.66 |
| Lens length | 101.54 | 116.35 | 133.85 |
| Back Focus Distance | 12.12 | 12.61 | 16.91 |
Closing Thoughts
The Canon EF-S 15-85mm was a welcome addition for Canon EF-S cropped camera users in 2009, and Canon has yet to come out with its equivalent for the RF mount. I know the common convention is to purchase full-frame lenses to use on crop cameras, but that is very impractical for a normal zoom range. Canon certainly needs a lens that starts with 15mm, as it was certainly welcomed by me on the EOS-M mount with the tiny 15-45mm.
Just a Reminder!
With all patents and patent applications, I have to stress constantly – this is simply a look into Canon’s research; the only thing we can quantify accurately is that Canon is researching this. A patent application doesn’t mean they are going to release this in the next month, or even year, or even at all.
Also hope Canon's revising the 18-45 so future budget RF-S bodies have something more useful. Still can't believe they started it at 18mm vs the 15mm of it's predecessor!
A way of decreasing manufacturing costs.
That's been my favourite walk-around if I didn't have the 24-105 mounted.
Or a 10-22 as the extra 4mm is handy compared with the 10-18.
But maybe three lenses?
→ f/2.8 High End Z type 15-60
→ f/4.0 High quality fixed aperture 15-60
→ f/2.8...5.6 good quality var aperture 15-85 like the older EF-S version
And the EF-S 15-85 is of really good quality, very low noise AF, IS and reasonably sharp at least for 4k video - the R7s 32 MPix sensor reveals the non-perfect sharpness but photography is more than just pixel peeping.