Extension tubes are hollow metal tubes that attach between the camera and lens.
The longer the tube or combination of tubes, the greater the degree of magnification. A bellows unit consists of front and rear standards, which couple to the lens and camera body joined by a flexible, accordion-like extension. Reversing Rings and Stacking Rings Reversing the lens on the camera face plate, with the aid of a reversing ring, increases magnification and may actually improve image quality. A reversing ring is an adapter that mounts to the camera on one side and the front of the lens on the other. Automatic functions are lost when the lens is reversed, so the lens must be stopped down to the correct shooting aperture either manually or with a double cable release made specifically for that purpose.