Great to rent if you know you’ll be needing it or just in case, the EF 1.4X II extender is a great piece of kit to have in your bag. Working with lenses 135mm and up as well as select zooms, the extender multiples the given lens’s focal length by 1.4x. The results of adding the adapter reduces the lens’s effective aperture by 1 stop, yet autofocus is retained for lenses featuring an f/4 aperture or faster. The second iteration, this adapter adds enhanced weather sealing and improved coatings for less barrell reflectivity. Compatible with 135mm lenses and longer (not including 135mm soft focus), as well as the following zooms: EF 70-200 f/2.8L, 70-200 f/2.8L IS, 70-200 f/4.0L, 70-200 f/4.0L IS USM, and 100-400 f/4.5-5.6L IS