I have a very similar lens to the one you describe. However, on mine the focus ring is actually rubber or rubberized metal, otherwise it sounds exactly like you describe. Mine too has the 1:1 marked scale, but if you simply focus on a tape measure at the minimum distance and read the markings at the edges (like I did), I think you'll find that it doesn't even magnify to 1:2. It gets close, but not quite. PS the image area of 135 film is 24mm high X 36mm wide or approximately 15/16" X 1 13/32". Now remember that many viewfinders do not show 100% of the image area so you shouldn't be able to see those spans/marlings on the tape measure at minimum focus distance if your lens infact magnifies at 1:1. That should tell you where the lens stands so to speak. I realize however that it still won't answer the question of why those marks are on the barrell. Mine doesn't have a second (1:2) scale. Clifton Painter
