AF180 ED-IF, the first "crinkle finished" one, non-D. The closest marked distance is 1.5m/5 feet, but it focuses a bit closer than that. I used the 20mm Kenko tube,and focused by moving myself forward and backward to absolute Minimum Focus Distance. Images USM'd 200/.3/0 then reduced 50%, same USM, then 1000 pixels wide, then USM's same,then shrunk to 640x wide and USM'd. These show you the smallest frame area you can get with this 180 with a 20mm tube...the 25mm tube will get you closer still.Focus range is apprx. 39 to 81 inches from the focal plane indicator on the S2...subtract 8 and 3/4 inches for front of the lens measurements of the focusing range with the 20mm tube installed.