SIGMA 135mm F1.8 DG HSM | Art delivers ultra-sharp images with a beautifully smooth bokeh effect to the out-of-focus areas of the image. It offers the outstanding resolution required for 50MP or higher ultra-high-megapixel DSLRs. By incorporating its latest innovations in design and optical glass and rethinking every aspect of the lens, SIGMA has ensured outstanding image quality all the way to the edges, establishing the new standard in 135mm telephoto lenses. With resolution so crystal-clear that individual hairs can be discerned in a portrait, this large-diameter lens also delivers a beautiful bokeh effect, giving photographers everything they need. It is ideal for close-ups and full-body shots, with subjects standing out against a pleasantly blurred background. In addition to standard portraits, including bridal shots, this lens is a top performer for live events, with its super-fast autofocus capturing subjects with ease. To deliver the ultra-high resolution that brings the best out of 50MP or higher ultra-high-megapixel DSLRs, the focus mechanism features SIGMA’s floating system. No matter what the distance from the subject, this lens offers top performance from the center to the edges of the image. By minimizing distortion as well, the lens delivers impeccable image quality—no need for digital adjustment during image processing. Moreover, the large diameter with F1.8 brightness makes possible a body shot with an impressive bokeh background. In sum, this lens puts a full menu of compositional options at the photographer’s fingertips. The large HSM（Hyper-Sonic Motor）delivers ample torque to the focusing group for outstanding speed, ensuring exceptionally stable performance even at lower speeds. Along with the optimized AF algorithm, this feature delivers fast autofocus photography. In addition, the focus limiter makes AF highly responsive to distance from the subject for even more nimble performance. To use USB Dock, Please attach a USB Dock to your lens' mount part, just like you attach your camera to the lens. Please use the supplied USB Cable and connect to a computer which has the dedicated software “SIGMA Optimization Pro” installed. For further information on how to operate the product, please refer instruction manual of “SIGMA Optimization Pro”.