Canon Patent Application: Powershot lenses including an 18-70mm design

In this patent application that we discovered, we have found an intriguing number of what appears to be powershot compact camera lens designs.  It's usually a pretty simple process to determine if a lens design is destined for the powershot compact cameras.  What is different from a powershot lens design, is that the image height parameter usually differs through the zoom range. Perhaps, unfortunately, it's common for Canon to design a lens so that the image circle is actually smaller than the sensor at the widest focal length, thus needing in-camera corrections to correct for the significant image distortion that would occur.  This patent application actually addresses this and the effect that this distortion has on autofocus.

In machine converted Japanese, and patent language to boot Canon describes their intention as;

In  order to obtain a high optical performance over the entire screen with little variation in aberration during focusing while having a predetermined angle of view for the zoom lens, the zoom type, the refractive power of the focus lens group, the lens configuration, etc. It is necessary to set appropriately. Furthermore, it is necessary to appropriately set the lens configuration of the lens unit positioned on the object side of the focus lens unit. 

An object of the present invention is to provide a zoom lens having high optical performance over an entire object distance and an image pickup apparatus having the zoom lens, which reduces aberration fluctuation when focusing at a wide angle of view. 

This patent application has basically all the different G series compact camera lenses in it, including one we've never seen before - an 18-70mmm powershot lens design.  Nikon got everyone excited when they announced the Nikon DL 18-50mm and then turned around and canceled the project on everyone including myself (it was going to be my first nikon camera).  Could this be a sign that Canon is thinking about coming up with a model similar?  Time will tell.

We will show three examples that this patent application goes into, there are more, but they are simply variations of the same 3 themes;

First we have the "normal" zoom of the powershot G series 1" cameras; this example covers 24-115mm in equivalent focal length on a 1" sensor.

zoom ratio 4.74 
focal length 9.00 22.58 42.68   
F number 2.06 3.09 4.12   
half field angle 35.71 10.47   
image height 6.47 7.65 7.89   
lens total length 60.38 65.31 77.00 
BF 3.00 10.18 8.34  

This next example covers a lens design for an APS-C sized sensor, something similar to the G1X Mark III perhaps, with a focal length of 24-70mm equivalent.

zoom ratio 2.75 
focal length 15.62 28.71 42.97   
F number 2.50 2.88 3.15   
half angle of view (degrees) 35.65 24.78 17.63   
image height 11.20 13.25 13.66   
lens Length 85.01 71.06 73.01   
BF 3.00 19.72 16.57  

The final example and possibly the most interesting, is a zoom lens for a 1" sensor with an 18-70mm equivalent focal length.  Canon if you are listening, yes, please.

zoom ratios 3.66 
focal length 6.79 12.87 24.88   
F-number 1.85 2.50 2.88   
half angle of view (degrees) 43.60 30.74 17.59   
image height 6.47 7.65 7.89   
lens total length 60.00 54.02 54.00   
BF 3.00 4.04 6.02

Again, as with all patent applications. This is an area of Canon research, it may never end up in an actual product.

Japan Patent Application 2019-091099