Like loads of people, I have been on the lookout for a good second hand Cannon 300mm f2.8, but the prices are high to say the least. I have been offered the chance to buy a mint Sigma 300mm f2.8 EX DG HSM and just wondering if any of you have used or own one and could vouch for its quality vrs the Canon. The price is about half of what a decent Canon would be btw. Thanks