Canon EF 100-400mm f / 4.5-5.6 L IS USM lens (77mm filter thread) (Accessories)
As previously satisfied owner of the Canon 70-200mm 2.8 L IS lens that I use mainly in sports photography, I had the fainter 100-400er always irritated, because it provides the APS-C my quick Canon 40d an extended telephoto range, which you can use e