Canon Extender EF 2X III

I’ve been using this with my 300mm f/2.8L IS II and the autofocus stays snappy even with the 2x reach. The weather sealing gives me confidence shooting in light rain, which is a must for wildlife work.

Went from a 70-200 to a 140-400mm beast without losing any sharpness, the autofocus stays snappy even for birds in flight. It's just a solid, reliable piece of kit that does exactly what it's supposed to.

Used it with my 70-200mm on a safari trip and was shocked how sharp the shots still came out even at 2x. The autofocus locked onto birds in flight without any hesitation. Definitely a solid performer if you need extra reach without carrying a bigger lens.