Had the same question too before I went on my alaskan trip earlier this year. I ended up buying the 70-300 IS intead of bringing the 70-200 F4L and felt it was a good decision.
Most of the chances to shoot wildlife came during boat tour, bus tour, or even flights during the day. These are not very stable platforms to shoot from, so the IS comes in very useful. The longer reach was also important as well, as we were usually quite far from the targets. The 70-300 IS was also pretty good in the sharpness and contrast, so had no issue shooting wide-open. The focussing was also pretty fast on the 400D.
Also, the lightweight 70-300 IS as opposed to the 100-400 L (another lens to consider as well) helps prevent shoulder/back ache (70-200 F4L is light as well)![]()
Hi mpenza,
thanks for the great insight! based on your comments, the IQ at 300mm is good?
can i assume u bought the lens this year? that means not affected by some barrel sagging problem earlier right