I am thinking of getting another lens to go with my colection. It will either be the 100-400L or 300L f/4. Which one would be the better one to get for shooting birds and car racing? I have the 1.4X for the 300L if I got that one but, was thinking about if I needed to zoom out or something. But, anyway, anyone with an idea who has used both and what they decided on?
Thanks,
Dooglla

