I'm in need of a new lens school sport/events/general photography to pair with my 5D3. Looking at around $1500 total, definitely can't extend to the Canon 70-200mm f2.8 IS II - laying that to bed from the outset. Thoughts on the following setups? Canon 70-200mm f2.8 (original) + Canon 2x Extender III Sigma 70-200mm f2.8 + Canon 2x Extender III Canon 70-300mm L Canon 100-400mm L My reasoning for the 70-200mm f2.8's + extenders is that I can then also use them for low-light stage performances/low-light indoor sports as well as being generally more versatile. I'll be going 2nd hand for the 70-200's and perhaps the larger ones, although the larger focal lengths do not seem to come up for sale as much. What would you choose for an all-round school lens, keeping in mind 3/4 of all photos will be at sporting carnivals.