I did a lot of reading before buying a TE and came to the conclusion that as long as the individual lens in question was working correctly (operating the frameline selector), there was not much to distinguish the first and second versions. Optically, they are the same. The mount for the second version is a little more compact, but it offers less "shading" than the first version. The second verion has a tab, which individuals may or may not like. The second version also has the DOF scales, which looked very visually confusing to me (and also didn't work for an R-D1).