One of the disappointments for me with the RF-S system is the normal kit zoom range from 18-45 instead of 15-45mm.
In this patent application, Canon sets out to create a 15-45mm that hopefully isn't plagued with the same quality assurance issues as its older EF-M brother. I swear I went through 5 copies until I finally got one that was on point and quite good. Once I did, I loved the focal range having been used of the 18-55mm kit zooms in the past, the 15-18mm was well appreciated by myself.
In this patent application, Cann wants a small lens with spherical aberrations and others more corrected than prior patents allowed for.
However, in the zoom lens disclosed in Patent Document 1, the entire lens system is large and it is not possible to achieve sufficiently high image quality. Furthermore, in the zoom lens disclosed in Patent Document 2, various aberrations such as spherical aberration and coma aberration are not sufficiently corrected. An object of the present invention is to provide a zoom lens with good optical performance over the entire zoom range.
The EF-M 15-45mm is quite similar in terms of optical design. This design appears to be missing one element between L11 and L12, otherwise it's a very similar design.
The back focus on the embodiments is quite tight, which makes me wonder if this was originally in the pipeline as a EF-M 15-45mm II, instead of an RF-S lens. However, even though the ingress into the mount is significant, there may still be enough room for the lens inside of the mount body to sit the rear element back that far. As such, I'm not putting this as an RF-S lens. It probably was Canon's intention though as I doubt any designer was working on new EF-M designs in 2022.
The age of the RF-S 18-45 for the RF-S probably has little bearing on a newer 15-45 as Canon in the past had replaced an earlier kit lens on mirrorless fairly quickly (3 years).
Canon APS-C 15-45mm F3.5-6.3
Wide-angle Intermediate Telephoto focal length 15.36 29.82 43.10 F number 3.60 5.10 6.44 Half angle of view 35.76 23.75 17.59 Lens total length 76.36 68.85 73.51 BF 10.45 10.45 10.45
Canon APS-C 15-45mm F3.5-6.3
Wide-angle Intermediate Telephoto focal length 15.37 29.58 43.10 F number 3.60 5.10 6.44 Half angle of view 35.41 24.79 17.59 Lens total length 79.34 71.19 76.32 BF 10.18 10.18 10.18
Canon APS-C 16-45mm F3.5-6.3
Wide-angle Intermediate Telephoto F number 3.60 5.10 6.44 focal length 16.23 34.90 43.10 F number 3.61 5.10 6.44 Half angle of view 32.27 20.40 17.59 Lens total length 88.10 84.74 88.68 BF 10.87 10.87 10.87
Source: Japan Patent Office: 2023-182958
79.34 is a little longer but it retracts to 71.19 anyway.
I am assuming that it will be in the most compact position when stored.
The RF-S 18-45 is much smaller than a kit lens needs to be.
They could have just gone with 15-45 but now that we have the RF-S 10-18, 18-45 makes sense.
Nikon has the DX 16-50 on a 1.5x crop.
That alone is good enough reason for Canon to make an RF-S 15-45.
Except for just one use case:
Being small and light for travel or else.
In that case it serves that purpose well, doesn‘t it?
I found the 15-45 to be a nice walkaround on the M's once I found a good copy. I really dont' want to go back to 18mm
I still prefer the 11-22 over the 15-45, though, the extra width is great for getting more environment into indoor shots, like in cramped cafes.
I am not sure that I see the need for a dedicated macro lens.
Although I do expect a few RF-S portrait prime lenses.
Even though those are not as necessary with the bargain EF f/1.8 prime lenses.
So at least 3 APS-C specific 1:1 or better lenses. The 28 and 35 even have a built-in ring light, which I’d like to see in a future RF macro like the MP-R.