While 70-200mm lenses are generally the standard for telephoto zooms, if you do not need a wider aperture, a 70-300mm lens can offer you more reach on the telephoto end and is often far cheaper than a 70-200mm f/2.8 or f/4 lens. Such is the case with the Tamron 70-300mm f/4.5-6.3 Di III RXD, and this excellent video review takes a look at how the lens performs in the real world.