Simply put, the Canon EF 100mm F/2.8 Macro USM lens is an excellent lens. It provides great optical performance through all parts of the focus range and features a solid body light enough to be well suited to for travel and trekking.
This lens features a maximum aperture of f/2.8 which provides excellent ability to handle lower light situations. Being purpose built as a lens for macro photography it has a close focusing distance of .31 meters at a magnification of 1:1 meaning you can fill the entire image frame with subject matter as small as your camera's image sensor. A focus limit switch allows selection of a narrower .48 meters to infinity focus range to significantly reduce autofocus time as closer focusing distances occupy an amount of focus travel proportionally much greater than in farther focus distances.
It's a versatile choice for a wide range of photographic subjects: nature, scientific, product, miniatures, stamps, baby hands and feet. The 100mm focal length is also suitable for classic portraiture. A Canon ring type USM drive (Ultra Sonic Motor) provides a fast, virtually silent focusing experience with full time manual focus override. The lens is popularly used on Canon EOS full frame bodies and also APS-C sensor DSLR's.For maximum stability and compositional convenience a lens tripod collar is available separately. Magnification can be increased further with the addition of optional extension tubes, close-up filters, or tele-converters. Canon Macro and Ring Lights are also available.
The EF 100mm f/2.8 Macro USM Lens from Canon will focus over the full range from infinity to true life size (1:1 reproduction ratio) macro. Ideal for photographing details and small subject material, it also serves as a very sharp prime telephoto lens for portraiture and other applications. It provides a combination of versatility, image quality and superb handling.
A high-performance ring type Ultrasonic Motor provides fast and silent AF throughout its focus range, and full-time manual focusing permits the close-up or macro shooter to instantly override the AF whenever necessary. A 3-group floating system results in excellent delineation at all focusing distances and a focus range limiter function enables faster autofocus times within one of two appropriate ranges.