Bellows, a concept that comes from Latin follis, can be used to refer to the device that allows to accumulate air and then expel it in a specific direction. These instruments usually consist of a container with a flexible skin on its sides, a valve that allows air to enter, and a barrel through which, when the sides are folded and the volume of the device is reduced, the air comes out.
The bellows, in short, are mechanical devices that store air for later, when subjected to a certain Pressure, expel it with a certain purpose. This object inflates when air enters its structure and deflates when it is released.
The bellows generally has a valve that avoids the return of the expelled air, although it can also have different openings for the inlet and outlet. Its operation is similar to that of a pneumatic pump.
In the field of metallurgy Bellows are used to blow air into the fuel, increasing the amount of heat and the level of combustion. The forge that is used when forge Metals, for example, have a bellows to stoke the fire.
Musical instruments like the bandoneon, the accordion, the pipe organ and certain bagpipes they also have bellows. In these cases, the device contributes to supplying air or regulating that which the musician expels by blowing.
In the field of PhotographyFinally, the bellows is a accessory It is used in certain cameras to favor lens movement and make focusing easier. These bellows, which fold and expand as needed, create a dark space between the lenses and the film or plate.
Bellows are part of a group of accessories in which there are also the extension tubes or rings. It is an ideal complement to the objectives it serves to make approach photographs. It is known as close-up photography or approach to that which brings the object closer and makes it larger, thus improving the observer’s appreciation of its details. Thanks to this type of capture, the human being can see certain features of the world that surrounds him that usually go unnoticed by him.
Although the bellows and extension tubes are different pieces, each with its own characteristics and purposes, their operation is quite similar. For example, the two are placed between the lens and the camera to increase the distance between the focal plane and the subject to be captured. Through its use it is possible to descend below the minimum distance limit of focus, thanks to which the object takes up more space than it normally would.
One of the main differences between extension tubes and bellows is that the latter allow the user to adjust the degree of clearance between the lens and the camera body. For this they usually have a high precision mechanism that consists of metal bars on which the objective every time we turn some knobs in the desired direction, depending on whether we want to zoom in or out.
One thing that both accessories have in common is that they can retain the automatic features of the camera, although this varies by model and has a significant impact on the price. Extension bellows are supplied with a plug that allows insertion of a double release cable, which operates the shutter and the diaphragm at the same time, so that the aperture can be held open for focus and closed at the time of shooting.