While some photographers will endeavor to use the Canon EOS R’s magic touchbar for changing their ISO, that’s not the best use. Personally, I set my lens control ring to aperture and set ISO and shutter speed to the camera’s dials. So, what is the touchbar useful for? Honestly, not a whole lot while shooting. But, where it comes into use is with playback.
Through the settings, you can set it up so that tapping the left side rates an image and the right side locks it. This means that, when you’re going through images on the camera, you can star and rate in camera. Lots of photographers love doing that on the computer, but if you do it in-camera you can make your post-production a lot faster. You’re going to chimp your LCD and go through the images anyway, so why not add stars to the photos? Upon import into Capture One or Lightroom, you can get to those rated images immediately, and they can be the first ones you edit. Then, the other photos can be sorted a bit later.
So, when you’re shooting the magic touch bar may be essentially useless. But, if you’re reviewing your images after a wedding, event, or portrait shoot, then you can make the editing and delivery process go faster.
If you’re a Canon EOS R owner, I encourage you to give it a shot.