Sigma Telephoto 180mm f/3.5 EX APO Macro DG Autofocus Lens for Pentax AF

Taking picture of small animals and insects can be difficult, because they often run or fly away, or can be dangerous or become aggressive if you approach them. Therefore it is advantageous to have a greater working distance between the camera and such subjects. Longer focal length lens can provide this greater distance, but most long lens do not focus close enough to provide a large image of small subjects. The tele-macro type lens solves this problem by producing a large, high quality image, up to life-size, while maintaining a long working distance. This can enable you to capture on film the world of photomicrography, without disturbing the subjects. The 180mm F3.5 APO MACRO lens has a very narrow field of view, and can allow very narrow depth-of-field for selective focus and less distracting backgrounds. This lens is most desirable for photographers who are serious about producing high quality images both of macro subjects at life-size reproduction, as well as normal telephotography. Floating Inner Focusing System The Floating Inner Focus System of the APO MACRO 180mm F3.5 EX HSM provides high quality optical performance and superior handling and stability. This system moves two lens groups within the lens, so the lens' physical length remains unchanged. This technique also maintains good correction for Spherical Aberration and Astigmatism, and provides extremely high optical performance from infinity to 1:1 Macro. It is possible to use 1.4x or 2x Sigma Apo Tele Converters. Macro photography can be further enhanced by the 1.4x APO EX tele-converter, which allows the photographer to use the new SIGMA APO 180mm F3.5 MACRO lens as a 252mm F5 lens while maintaining auto focus function from infinity to 1.2m(47.2 in.) with Canon, Nikon and Sigma cameras. At distances closer than 1.2m (47.2 in.) the lens automatically switches to MF mode. When this lens and the 1.4x EX tele-converter are used with Minolta or Pentax cameras the lens must be focused manually. When used with the 2x EX tele-converter, the 180mm F3.5 len