Went to a local park with my Canon 7D, 70-200 2.8 lens and the new Yongnuo clone of the Canon extender. I had to compensate some from earlier underexposed images, but I think it's going to work out. The Yongnuo clone is about half the price of the Canon version, but has gotten decent buzz. http://petapixel.com/2015/01/05/yongnuos-clone-canon-2x-teleconverter-costs-180-instead-449/