The Pentax 55mm f/1.4 DA* SDM Autofocus Lens is a compact and bright short-telephoto lens of the highest order, made exclusively for Pentax digital SLR cameras. In a stocky housing ready for harsh conditions, you'll get a bright f/1.4 aperture-worlds away from the experience you're used to with more common zooms-that opens up new creative doors to you as a photographer.
This lens was born to shoot between f/1.4 and f/2.8, and comes with a 9-bladed aperture diaphragm which shows up as perfectly round when you stay between f/1.4-2.8. Shoot dramatic portraits with bright point light sources behind the subject, and you'll be dazzled with lovely diffuse, circular out-of-focus highlights that make everybody look better. Beyond portraits, this lens works well any time you would use a moderate telephoto focal length.
The focusing system of this lens is SDM only; there is no screw on the rear of the lens barrel to have the AF driven by a body-based motor. This allows the lens to move incredibly quick, driven by an internal motor and with the Quick-Shift system providing manual override capacity to you any time you want it with no buttons to switch; but you'll need a Pentax body which allows SDM autofocus (all current Pentax bodies support SDM, but the *IST series does not).
Note! Does NOT provide autofocus upon non-SDM-enabled Pentax cameras.
Construction 8 Groups/ 9 Elements Angle of view 28.6 degrees (w/PENTAX DSLR) F stop range f/1.4-22 Closest Focusing Distance 0.45m (1.5 ft.) Maximum Magnification 0.173X Filter Size 58mm Dimensions (Length x Diameter) 2.6" x 2.8" (66.0 x 70.5mm) Weight 13.2 oz. (375g) Notes Quick-shift focus, SP (Super Protect) coating, Rounded aperture (F1.4-2.8), Dustproof and weather resistant, SDM supersonic autofocus motor, SDM-only autofocus (manual focus on non-SDM bodies)