When I started out shooting wildlife I had a 55-250mm lens. One of the biggest draw backs was I found myself cropping way to much to get the picture I wanted. So I bought the 100-400mm and was real happy with it (with and added benefit of better IQ). You cannot always get close enough to animals to get a good clear view of there eyes which seems to really enhance the picture. So the extra reach does help a lot. In fact, I find myself at 400mm most of the time. You can go with a 400mm prime, but I also find the zoom to be handy because the 400mm was to big for shooting things like my kids soccer games (sports with good light outdoors). So the 100-400mm range worked good for me (although I would love to have the 500mm, it is a bit out of budget for me).


On of the big complaints I hear/read for the 100-400mmis the push/pull zoom action, but it was never really an issue for me.It was something that I got used to quickly, and it never really bothered me. I used this lens so much that when I got other lenses I had to get used to the rotational zoom action again.


Just my two cents for what ever it is worth.


Pat