A classic for close-ups, the Canon EF-mount 105mm f/2.8 EX DG OS HSM Macro from Sigma is a short-telephoto prime characterized by its ability to achieve a 1:1, life-size magnification along with a 1' minimum focusing distance for macro applications. The optical design employs two SLD elements to virtually eliminate chromatic aberrations and color fringing throughout the focusing range for improved clarity and color rendering. A Super Multi-Layer Coating has also been applied for greater contrast when working in strong lighting conditions.
The primary reason to use a macro lens is for the high, 1:1, 1x reproduction ability macro lenses possess. The Sigma 105mm f/2.8 EX DG OS HSM Macro Lens and similar true (in my opinion) macro lenses can reproduce the subject at life size on the camera's imaging sensor. Since your camera's imaging sensor is tiny compared to your monitor or your print, subjects reproduced at life-size on the imaging sensor can appear MUCH larger than life-size. For most macro lenses, the high reproduction ratio is completely a bonus over an equivalent non-macro lens, because the macro lens also has a standard lens' capabilities (more on this to come).
The 105mm f/2.8 EX DG OS HSM Macro Lens is Sigma's first macro lens to feature OS (Optical Stabilization) and replaces the . The Sigma 105 OS Macro lens has been in my kit for just over two years and has seen intermittently regular use. I have been quite pleased with the results the lens has delivered for me.