boubou wrote in post #3821197
Don't you think the f/4 with an extendeur will be too slow to capture animals or wildlife?
I use the 70-200 f/4 non IS and 1.4x tcon in daylight and even into dusk of wildlife such as birds with no problem. Add a monopod and you can shoot relatively low shutter speeds at longest FL easily down to 1/160. This combo is pretty cheap too. 98-280mm for about $800.
For my situation IS would be nice but not critical. One thing that I would like though, and something you may consider is the effect the aperture has on your shots. If you really want to isolate subjects and get better bokeh the 2.8s will be better. That is not to say that the f/4s are bad by any means though.
Also, have you ever handled any of these 70-200s? They 70-200 f/4 is super light and the 2.8 IS is larger and quite heavy after a while. I don't really mind the weight and size but some people find it too much. You may want to consider this.
Oh, forgot to add that IMHO, based on experience with the f/4, f/2.8, and f/2.8 IS the f/4 hands down has the best IQ. My copy is quite sharp throughout the FL and throughout the apertures and there is virtually no CA or purple fringing anytime. The other lenses had these issues to some degree.