Touchscreens on cameras aren’t so much a bad idea as one that should be used in moderation. A nice slim Panasonic that doesn’t want to ruin its look with buttons should certainly have a touchscreen. But a DSLR? I don’t think it would work out, but Canon has apparently put enough thought into it that they’ve decided to file a patent. It’s nothing revolutionary and it’s far from a full product walkthrough, but it’s worth taking a look at, if only to recognize how simple it could be when implemented.
The most frequently-adjusted settings, aperture and shutter speed, would be changed by vertical or horizontal swipes. Other settings would be accessible through simple touchable menus; the simple rear LCD layout of current Canon LCDs would be easy to modify to allow this. It would disable the touchscreen when you put your eye up to the viewfinder, much as it does today.
It’s not a question of whether it can be done; if they wanted to, they could have made something like this years ago. The question is whether they can make it better than the dials and buttons SLR users have been thumbing for decades. Being able to adjust the shutter down a couple steps without removing your eye from the viewfinder is an example of something that might be difficult with a touchscreen. At the same time, navigating and editing your photos in-camera would be simpler if you could swipe, zoom, and so on.
At any rate, it’s not a product announcement. Canon merely had some ideas and wanted to get them on the record as their intellectual property. Maybe in a year or two we’ll see something more substantial.