Extension tubes allow you to turn standard fixed focal length lenses into macro lenses. An extension tube kit is available which includes six extender tubes: 0.5 mm, 1 mm, 5 mm, 10 mm, and 22 mm for extension from 0.5 mm to 38.5 mm. The tube(s) mount between the camera and the lens, making it possible for you to focus a C-mount lens at a much closer distance than normal.