I am a bit confused here, Emil. For focussing at infinity, one does not need extension tubes for the 120mm makro-planar. The beauty of this lens is that it is a very, very good light telephoto lens which is also optimised for close range makro work. One can debate whether the focal length is more or less suitable for portrait work, but certainly not the image quality. And as I said in an earlier comment, I dislike the unbalance a 501CM gives me handheld with the 180, therefore chose the 120.