The Canon EF 100-400mm f/4.5-5.6L IS II USM Lens offers professional grade build quality, fast, accurate and quiet AF, very effective image stabilization and very impressive wide open image quality over the entire and very useful 100-400mm telephoto focal length range. Downsides?

If you want a quality telephoto zoom with longer reach, consider the EF 100-400mm IS USM, now available in a Mark II edition. Compatible with both cropped and full-frame bodies (and delivering equivalent coverage up to 640mm on the former), it's ideal for capturing distant action or wildlife.