Quote Originally Posted by paulnj
Kristen,

Most people here use them to get closer to macro(1:1) or beyond macro when used on a true macro lens. Wildlife shooters with HUGE PRIMES(600F4) use them to reduce the minimum focus distance for smaller subjects . All they are is a spacer between the body and lens that gives you you closer focus distances while robbing you of your infinity focus. The more extention you use, the narrower the gap between close and far focus distances.
Very good explanation Paul. Tubes are very useful, but won't be for everyone. Everyone has a different shooting style and technique. Some will find them useful others not.