Macro extension tube works by separating lens further from the film or digital sensor. The further away the lens is, the closer the focus, the greater the magnification.
It does not affect image quality as there is no optics inside.
1.Camera Body Mount Adapter
2.Lens Mount Adapter
3.9mm tube (Tube 1)
4.16mm tube (Tube 2)
5.30mm tube (Tube 3)
The more tubes you add, the closer the focus and the greater the magnification.
There are no electrical contacts in the extension tubes. Exposure has to be adjusted manually. Aperture control is not available if you use a lens which does not allow you to manually adjust the aperture (without an aperture ring).