The smc Pentax-DA* 55mm f/1.4 SDM lens is a professional prime lens for the Pentax K-mount. It is designed for portrait usehttp://www.dpreview.com/lensreviews/pentax_55_1p4_p15/ DPReview: Pentax smc DA* 55mm 1:1.4 SDM review with a 35mm equivalent focal length of 82.5mm. The lens features weather sealing, an SDM ultrasonic motor for quiet autofocus, and has 9 rounded diaphragm blades for smoother bokeh. Autofocus speed is similar to an equivalent screwdrive lens.http://www.digitalcamerareview.com/default.asp?newsID=3916&review=pentax+da+55mm DigitalCameraReview: Pentax DA* 55mm f/1.4 SDM Lens Review
References
External links
SMC Pentax-DA* 55mm f/1.4 SDM Bojidar Dimitrov's Pentax K-Mount Page: DA* 55/1.4 SDM