This probably belongs in the lens forum, but I figure that only macro shooters might know the answer, so I am placing it here.
My standard macro lens is the Canon 100mm L. This lens will not take a Canon telextender directly, but some folks have noted that you can mount the lens on a telextender if you place a 12mm extension tube between the two. I've experimented a bit with a Canon 1.4X II but wonder if anyone has learned more than I have about this.
As a very rough approximation, I found that the combination decreases MWD by about 1 cm. It increases maximum magnification to roughly 1.6:1. One can of course reach this level of magnification with a longer extension, without the telextender, but at the cost of a much shorter MWD. And for a given level of magnification, it gives a greater working distance than the lens alone.
Has anyone experimented to determine the optical quality of this combination? I have no idea what putting empty space between the lens and the extender does to image quality.
Thanks for any information.
