Composite of reduced but uncropped images made with Canon 50mm f/1.8II and Kenko Extension Tubes. Only three of the 7 possible combinations are shown with the others intermediate. Note that there is a gap between the size image possible with no tubes at the near focus (.45m/1.5ft) and when using the 12mm (smallest) tube with the lens set on Infinity. As expected, the small amount of additional extension from the lens mount has little effect when added to all three tubes but it allows some benefit when used with the shortest tube.