Extension tubes do some strange things to the focal plane, as well as narrow the depth of field and shorten the focal range (you cant focuss to infinity, or indeed anywhere distant). I have tried mine on telephoto and wide angle zooms as well as macro lenses. If anything a fixed length macro is the easiest lens to use them on! With a zoom lens, the change in focal plane that occurred on zooming even a little was quite dramatic, and it took some careful adjusting of zoom and manual focus to get things right.
|