I'm looking into the Kenko line of teleconverters which I have heard good things about. I'll be using it on my Tamron 70-300mm VC. After looking on B&H, I noticed that there are two versions, Teleplus Pro 300 DG ($200+) and Teleplus MC4 DGX ($120ish). The Pro says it is compatible with EOS digital cameras, the MC4 says for EF lenses. Is the MC4 an earlier version, less capable model, or not even compatible with my Tamron? It just seems odd to me that the one designed for EF lenses would be cheaper, unless it is just an earlier version. Not sure if it is worth skimping and getting the cheaper version and risking worse image quality. I was just hoping there were some people who could provide some insight on the Kenko equipment. Thanks!