100-400mm lenses have long been popular for everything from bird photography to sports, as they offer a tremendously useful focal length range. While Canon offers a premium option of this lens, there is the much more affordable RF 100-400mm f/5.6-8 IS USM for anyone who wants to save some money or a bit of weight in their bag, and this great video review takes a look at the lens and the sort of performance and image quality you can expect from it in practice.