The biggest challenge for a concert photographer is to get the exposure right. It is almost impossible to use the camera’s built-in light meter as it gets confused by the huge differences and changes in light all the time.
For example, when there is a spotlight on the artist but the background is -like it often is- very dark, the camera compensates in order to lighten the background leading to overexposure on the artist. So most of the time it is better to go for manual exposure. But that means constant checking on the back of the camera if the exposure is still right. With a bit of practice, one will manage to adjust quickly to what goes on on stage but you still do have a fair chance to miss a scene or two. In this scenario, a mirrorless camera has big advantages. In the electronic viewfinder (or on the screen on the back) you see the actual exposure. And that means you don’t need to check the exposure each and every time. You can simply adjust and see the effect of that.
The Canon EOS R adds to that a new exposure mode that makes this even easier, the Fv or Flexible Priority mode. It combines the control of full manual exposure mode, aperture priority (Av) and shutter priority (Tv) with full auto. Here’s how it works: When set to Fv, aperture, shutter speed and ISO are all set to auto. But you can now adjust each of these manually, and the others will respond accordingly to maintain proper exposure. Or as I use it for concert photography; setting the ISO, the aperture and shutter speed to the desired values and choose ISO value to be controlled by the front wheel. Whenever the exposure is off, I dial in a different iso value. If I for some reason want to change one the of the other values I can use the back wheel to select them. And then change using the front wheel. All without taking my eye off the viewfinder and seeing the immediate effect.
A few other things I noticed while shooting this concert, the EOS R autofocus had no trouble to acquire focus. It did it fast and was spot-on. My 1Dx at much more trouble acquiring focus, sometimes hunting and not always spot-on. Incredibly helpful was the face detect, fast enough for this kind of concert I only have to develop more memory muscle to quickly jump from one face to another.