If you are using the lens for sport then "IS" is not needed due to the high shutter speeds required to freeze the action. When I had the 70-200 F4L, I used it for horse riding events and didn't need "IS" and when I use my 24-105 IS 4L for the same I turn it off. "IS" is more for stationary objects with slow shutter speed and not for action stopping. Best thing for slow shutter speeds is still use a tripod.


If you are looking at the 70-300mm IS against the 70-200mm 4L the 70-200mm 4L wins hands down.