Last month I bought a Canon 100-400mm f4.5-5.6 EF L IS USM for $5.00. It's a little beat up and had a small spot of fungus behind the front element. Last weekend I was able to get inside and clean the fungus off. Auto focus and stabilization function as normal. I'll have to work on my getting my exposure right, I'm not very familiar with the Canon system. Photographers of Threads