So I'm switching to a 5d mark ii from a T3i. My current telephoto is a 70-200 f4 IS with a 1.4x ii extender. If my math is correct on the crop sensor this gives me the equivalent reach of 448mm. On the 5d it will only be 280mm.
So I need help deciding if I should sell the 70-200 to fund a 100-400. I'm hesitant to do that because I absolutely love the 70-200. It is by far my favorite lens because of the quality of images I get when using it. Even with the extender on its amazing. It looks like the 100-400 isn't quite as good optically but obviously has the reach I currently have.
I shoot for hobby so I'm not going to own both at the same time. Does the 100-400 hold up against the 70-200 in the real world (not lab tests)? Or should I just keep the 70-200 and crop in post?
I shoot mostly landscape and only use telephoto sparingly. When I do us it, its for kids sports, wildlife, birds.