The Sigma 105-millimeters HSM DG is an aperture medium telephoto macro lens, which has a focal length of 105-millimeters, and the image circle of 35-millimeters, offering an advanced performance of close-up photography. The Sigma lens has a minimum aperture value of f/22, while the maximum aperture stands at f/2.8, making it ideal for close-up photos. Although, the Sigma lens does not have front element rotation, it does include a focus limiter, hypersonic motor, and full-time manual override, as well as optical stabilizer. Moreover, flare and super multi-layer coating reduces ghosting ensuring high contrast images. The angle of view of the Sigma lens is 23.3 degrees while its magnification ratio has the value of 1x or 1:1, providing extremely high optical performance. The system also compensates for astigmatic aberration and spherical aberration, as well as quiet and high-speed autofocus thanks to its Hyper Sonic Monitor. The prima macro lens consists of 16 elements, which have been arranged into 11 groups with nine rounded diaphragm blades.