Bellows: The Original Extension Tube
Bellows are an alternative to extension tubes used for macro and close-up photography. They’re based on a design from older large-format and field cameras, which used a mechanical system to extend and retract a lens from the film plane (which is now your digital sensor).
Much like extension tubes, bellows are positioned between your lens and your camera. They contain no glass optics, and their purpose is to create distance between the lens and the digital sensor to allow for a closer focusing range.
The difference between bellows and extension tubes is that bellows can be adjusted to increase or decrease the distance between the lens and the camera with precise movements. This allows more possibilities for creating the exact level of magnification you desire, and provides more versatility in combination with each lens you own.
Although bellows are a more versatile tool, they are generally not as compact as extension tubes and usually don’t provide auto-focusing controls.
Some high-end bellows systems come equipped with tilt/shift technology, which enables you to alter the orientation of your focal plane and to correct distortion caused by extreme camera angles. Use this piece of equipment when available as an alternative to other distortion correction techniques.