i have a siggy apo 70-300 and i m not sure wether to go for a tele convertor ir go and hire a nikon from calumet!!!! HELP!!!
I have the 100-400 but would definitely choose the 70-200 for an airshow - far more keepers IMO.
The only time I've used the 70-200mm is for take offs and landings, but nearly ever display I've been to this year and its a few, the 300mm + 1.4x TC has been on the 1D and even then there were some shots too far away. Duxford I got away with a 300mm, but I was right under the display axis, RAIT was a TC, most of the pro at RAIT were using 500mm and 600mm lenses, so 70-200mm just doesn't cut the mustard for today displays unless your not on the crowd line and can get closer to the action.