Method #1: Any lens you own will focus closer if you can add space between it and your camera. You can do this several ways.

Macro lenses have built-in extension that will let you take close-ups up to lifesize (1:1 or 1x) without any extra accessories. These lenses are more expensive that normal lenses, though, and unless you plan to do a lot of close-up photography, you can do just as well with other means.

Bellows are excellent and can be used with many lenses, but are very expensive and not very easy to use. You also lose a lot of functionality because a bellows seldom preserves any of your camera's auto functions such as diaphragms, autofocus, or, in some cases, certain exposure modes. They are also awkward to use in the field.

Extension tubes are cheaper, more practical, and usually retain most functions of your camera body. Add a 25mm extension tube to a 50mm macro lens and you can take lifesize pictures (you'll need to add 50mm of extension to a normal 50mm lens. Thanks to David Jacobson for pointing this out). There are formulas to determine how much extension you need for other lenses for different magnifications. Check the resources recommended at the end of this article.

Another way to get extension is to use a teleconverter. Teleconverters come in different sizes, the most common being 1.4x, and 2x. They are more expensive than tubes because they have optics, but they are more versatile. Besides being useful for close-up work, a 1.4x converter turns a 200mm telephoto lens into a 280mm lens, and a 2x converter makes it a 400mm lens. The price you pay is a loss of lens speed, a full stop for a 1.4x and two stops for a 2x. So an f/4 200mm lens becomes a f/5.6 280mm lens with a 1.4x converter attached.

However, I find this a simple way to get some extension without carrying a lot of extra junk in my camera pack, and I use it just as often for increasing the focal length of my telephoto lenses for those distant landscapes. If you purchase a teleconverter, buy one matched for your telephoto if possible, or a high quality one from a good lens manufacturer.

Method #2: Adding lenses to your existing lens. Many pros and advanced amateurs use a reversing ring to attach a lens backwards to the camera body. This increases magnification by changing the optical path. A variation is to use the reversing ring to add another shorter lens to the first lens. I haven't tried either of these methods, but they are commonly used and produce excellent results.

Another technique is to add close-up lenses or attachments . These supplementary lenses are fairly cheap and are measured in diopters and can be stacked on the end of your regular lens for close-up work. They are seldom recommended because the results are usually poor.

There is an exception, however. You can use Nikon's telephoto close-up attachments on any manufacturers lenses, and the quality is excellent. These close-up lenses are two-element, corrected optical filters designed for telephoto lenses. There is no light loss with these filters. The 3T (1.5 diopter) and 4T (3.0 diopter) are threaded for 52mm, and the 5T and 6T (1.5 and 3.0 diopters) fit 62mm threads. Put a 4T on a 200mm lens, for example, and you can go from 1.2x to 1.7x.

Method #3: You can combine one or more of the techniques above to meet your close-up photography needs. My technique for close-up photography is simple and low-tech. I use one of the Nikon close-up attachments with or without a teleconverter. I use a 3T with a 35-105mm AF lens and the 6T with a 75-300mm AF lens. I don't have to carry a lot of charts or remember to compensate for light loss. The camera takes care of most of the technical details. I can concentrate on the picture. I start with the close-up lens because full functionality of the camera is retained. Autofocus and multi-segmented metering are available. The daisy at left, for example, was taken with a Nikon 3T close-up attachment on a 35-105mm AF Nikkor mounted on a N90. The film was Velvia.

If I need more magnification, then I add a 1.4x teleconverter. I lose autofocus and matrix metering with the teleconverter, which is not a problem if I'm shooting a flower, but is a problem if I'm chasing a butterfly from bloom to bloom. Bugs don't hang around one place long enough for critical focusing or metering.

If you want to delve into this subject in more detail, or want to learn how to calculate reproduction ratios and other useful things, I'd recommend Close-Up Photography, the KODAK Workshop Series, or The Nature Photographer's Complete Guide to Professional Field Techniques by John Shaw.

Also check out this link, Macro Addicts