If you own a Canon EOS R Mirrorless camera and are looking at the RF range of lenses, a comparable option is the Canon RF 15-35mm f2.8 L IS USM. This lens features a very similar zoom range, constant maximum aperture, and USM-style focus motor. It does have one crucial addition though, which is Image Stabilisation. Built-in Stabilisation obviously improves your handheld shoots in all lighting conditions, making this one even more suited to available-light shooting. A feature common to the RF range, the 15-35mm lens features a control ring for you to adjust either aperture, shutter speed, ISO or exposure compensation, as you see fit.