Canon EF 70-200mm f/4L IS USM
Canon EF 70-200mm f/4L IS USM Lens Review
By: What Digital Camera (Feb 20, 2013)
Overall, the f/4 lens clearly plays second fiddle on paper but it is a very easy lens to carry and to use. Though it is expensive it is only roughly half that of the f/2.8 version, based on Canons SRPs. So there's probably a case for saying Canon has made the f/4 lens too good compared with the f/2.8 version. Its compromises and limitations are slight but its price advantage is substantial.