The use of extension tubes or bellows becomes vital in macro photography.
The closer the subject is to the front lens, the more the image that forms on the sensor moves away from the front lens. It therefore becomes indispensable to use the extension tubes or bellows to move back the sensor from the optics in ordre to obtain a sharp image of the subject.
Extension tubes are generally available in different widths (here 12, 20 and 36mm) and can be inserted between the lens and the camera either one by one or by coupling them.
I use the rings of Kenko because their ratio quality-price is very good. They transmit camera commands with good timing and one can benefit from the AF as well as the vibration reduction system when the lens is attached in direct.