1/600sec is nice but you can get as low as 1/400sec for moving objects and, if they're not moving, you can get even lower... a little under 1/100sec with the IS on that lens. I would recommend a nice monopod over a beanbag any day. It is indeed tough to shoot at those sorts of focal lengths when there isn't much light, but between IS and a monopod, you should do alright. I like the idea of auto ISO (what kind of camera do you have?) but yea, sometimes it'll get too high. The camera usually likes to bump up the ISO more just to be "safe" - so I would just keep the ISO manual and change it when necessary. In fact, I'd shoot everything manual, if for instance, the light and focal lengths aren't changing much. If they are changing (either or both) then I think you have the right idea, to shoot in Tv. But... I'd set my ISO if I were you.


I'm jealous of your safari!!!! The EF 100-400 is a very nice lens and you'll get some great photos!