Patent Application for Canon RF 16-28mm F2.8, 16-28mm F2.8-4 and 16-28mm F4 designs

This patent application is interesting from the curiosity standpoint but with Canon already creating both F2.8 and F4 ultra wide angle lenses not to mention a consumer STM I can't really see a place in Canon's current lineup for this lens.

As with all patent applications, it may never make it into production, but it's an indicator on what Canon was looking at doing.  I suspect that this design and the 14-35mm were competing designs.

Also, the back focus on these designs is arguably a little tight - but still doable.  The image quality at 16mm will also suffer from having to be digitally stretched to fit the full frame image circle.  Of course if Canon could make these cheap enough, they would also make a pretty good APS-C kit lens.

Canon RF 16-28mm F2.8

Focal length        16.45   21.00   27.50
F-number             2.88    2.88    2.88
Half angle of view  52.70   47.08   39.08
Real image height   19.00   21.00   21.64
Total length       138.01  130.43  127.00
Back focus          14.00   14.00   14.00

Canon RF 16-28mm F2.8-4

Focal length        16.45   21.00   27.50
F number             2.88    3.50    4.00
Half angle of view  52.70   46.87   38.91 
Actual image height 19.00   21.00   21.64
Total length       121.56  117.78  117.78
Back focus          14.51   14.21   14.50

Canon RF 16-28mm F4

Focal length        16.45   21.00   27.50
F number             4.10    4.10    4.10
Half angle of view  52.69   47.04   39.09
Real image height   19.00   21.00   21.64
Total length       124.60  121.27  121.49
Back focus          14.08   14.08   14.08

Canon Patent Application 2022-112179