EF 100-300mm f/4.5-5.6 USM, so it still works with my Canon EOS 1D, but it's really slow indoors. Not bad detail for hand held, f4.5 1/40s ISO800 100mm. I'm going to use it for carry around to avoid breaking an L series lens again which I need for weddings. Below was sharper due to more light, f10, 1/400, ISO 200, 100mm.
