Optically Speaking - Whats better - 100-400L or the 70-300L

Discussion....go!

and ill throw in AF speed as well..

fiveohmike wrote in post #13386427
Discussion....go!

70-300L has better IS and better optics from 100-300mm (to what exact degree i'm not sure) and adds 70-99

but 400mm is 400mm and an upscaled 300mm from the 70-300L definitely won't put the same crisp detail on a distant animal that the 100-400L will, so for any animal that you can't get to fill your frame as you wish at less than 400mm, the 100-400L will do better though all the same absolutely for sure

70-300L AF speed is very nearly like that of the 70-200 f/4 IS

Well, the new 70-300L is sharper across the frame, the least difference being in the middle. It has better IS and weather sealing. I wouldn't doubt it has faster af as well. However it only goes to 300 and the 100-400 goes to... well... 400, lol.