Close-up photography is the photography of subjects at a reproduction ratio lower than 1:1. In other words, the size of the image projected by the camera lens onto the film or camera sensor is smaller than the size of the subject. A reproduction ratio of 1:1 is where macro photography begins. This is a fairly universally accepted borderline (except by people in charge of marketing camera lenses). Thus, with a 35 mm camera, close-up photography is done with subjects bigger than the negative size, which is 24 by 36 mm. There is no generally accepted upper limit for the size of close-up subjects. My choice (with which you may or may not agree) is a reproduction ratio of 1:10, more because this is a round and practical number than for any deep theoretical considerations. Many general-purpose lenses have a minimum focusing distance that yields a reproduction ratio varying roughly between 1:5 and 1:10.
The picture at the right is an example of close-up photography (place the mouse cursor on the picture to read its information).
The rest of this page discusses equipment that you can use for close-up photography.
Macro lenses are lenses designed for macro photography, and provide a reproduction ratio of at least 1:1 (this applies to true macro lenses, not consumer zooms marketed as "macro" zooms, which are discussed here). Most macro lenses actually focus from infinity to 1:1, and therefore cover also the close-up range. In fact, macro lenses are simply the best tool for close-up photography.
Lenses with close-up capabilities
If you own a lens which can focus within the close-up range, it will probably be of adequate quality (assuming it does provide the reproduction ratio you need). This applies also to "macro" zooms. Such a lens is the first thing you should try if you don't already own a macro lens.
Close-up lenses are add-on lenses that you screw onto the filter mount in front of a lens. They decrease the minimum focusing distance of the lens they are used with, and typically provide an image quality ranging from adequate to good. Close-up lenses are the only solution available for cameras that do not have interchangeable lenses.
Inverted lens used as a diopter
By using a special coupling ring, it is possible to join two camera lenses facing each other at their filter mounts. One lens is attached to the camera body, while the other faces the subject with its back element. The lens further away from the camera functions in the same way as a close-up lens, and may provide better picture quality than the latter. This method is normally used for macro photography, rather than close-up, but reproduction ratios below 1:1 may also be obtained.
Extension rings are hollow tubes mounted between a lens and the camera body. They increase the distance between the two, and therefore extend the focusing range of the lens to closer distances. Contrary to close-up lenses, extension rings do not introduce their own additional optical aberrations, and a good lens with extension rings is likely to provide better picture quality than with close-up lenses.
Bellows are used to extend the distance between camera body and lens to a higher extent than extension rings, and also provide a way to vary this distance continuously. Bellows are normally used in macro photography, but if you own one, you may also use it for close-up photography, especially with lenses of long focal length. A limitation of bellows is that their minimum extension typically is around 20-30 mm, which may produce a reproduction ratio too high for your needs (i.e., you may have a "hole" left between the range of reproduction ratios available without and with bellows).
A teleconverter mounts between camera body and lens, and increases the focal length of the lens by a fixed factor (usually 1.4 or 2). Teleconverters do not decrease the focusing distance of a lens, but by increasing its focal length they effectively allow the lens to fill the frame with a smaller subject. Therefore, they can be useful in close-up photography. Teleconverters contain optical elements and therefore introduce additional optical aberrations. Picture quality may range between adequate and good, but is lower than with other methods like extension rings.