I have the 70-200 f4 IS and the 100-400 and I actually find myself using the 100-400 more. The 70-200 is definately the sharper lens but I like the versatility the 100-400 gives me most of the time. The lens is great for outdoor sports and places like the zoo. The range you have, especially if your using a crop camera is very useful (a 640mm 5.6 isn't bad at all). I'm sure the 300 will give you sharper images at that focal length but I personally don't want to be tied down to only one focal length.


The push-pull really isn't that bad and I got used to it fairly quickly. I would go with the 100-400. Just my .02!