The Sigma 50mm f/1.4 EX DG HSM is a lens suitable for full frame or APS-C reflex cameras (in this case it is transformed into a medium-the-teleobjective portrait, with a focal length that can oscillate from the 75 mm of the right standard to 100 mm of 4/3); This zoom is also characterized by the typical quality of the art family of the Japanese house, to which it belongs. Equipped with an ultrasonic HSM (Hyper Sonic Motor) engine, the 50 mm allows a very fast and extremely silent focus; In addition, it is always possible to make changes manually. The focusing ring is however very large, ergonomic and comfortable. The perspective has an extensive maximum opening and guarantees first -degree performance thanks to the use of lenses made of SLD glass (Special Low Desserion) and an asferic component Produced in printed glass that serves to correct aberrations and a diaphragm with lamellae rounded; The lenses are then covered with a Super Multi-Layer anti-reflex material, while the optical scheme uses 13 elements in 8 groups. The opening of the focal range up to f/1.4 also returns an excellent blur and allows you to take photos even with little light. The images are clear, with little vignetting and aberrations. Among the strengths of this model of the Sigma there are certainly the construction materials, very good, the meticulous finishes, the sharpness of the photos and the hint and custody included in the price; It also offers the option to replace the bayonet depending on the machine body (it is compatible with the Sigma, Canon, Nikon and Pentax camera). On the other hand, the weight of the 50 mm to someone could be excessive; In addition, the lens does not have the optical stabilizer and the lenses are not tropicalized: which makes it a zoom that are not particularly appropriate to adverse climatic conditions. The Sigma 50mm f/1.4 EX DG HSM is the ideal lens for professional photographers, to be preferably adopting on the sensors with whole format and to portray subjects in the foreground, snapshots, panoramas, shoot photos in the studio or street photography.