With the amazing Canon EF 200-400mm f/4L IS USM Lens getting a nearly-equally amazing $800.00 price reduction, I felt compelled to share an image captured with this lens.
In the spring, black bears come out of hibernation and the cubs enter their new world, full of first-time experiences waiting to happen. This little cub may have never seen an iris before and though it was still nursing from its mom, must have thought the iris looked like candy. After pulling some unopened flower buds from their stems and carrying them around like toys, this little cub approached the big open flower. It proceeded with great effort to pull the flower off of the stem. Too cute.
With a cub this young, you can count on the mother being close by. The zoom focal length range of this lens allowed me to frame the cub reasonably tightly at 560mm with the built-in 1.4x extender switched into the optical path (with some cropping) and then quickly zoom out to 270mm sans extender to vertically capture the momma bear standing upright with a cub between her legs. No single prime lens would have worked in this situation (unless the widest-needed focal length was selected with most images needing significant cropping).