The smc Pentax-D FA lenses are interchangeable lenses for Pentax SLR cameras. Their image circle covers the 35mm film format, and they also obtain optimum image clarity with Pentax digital SLR cameras. When these lenses are used with an *istD-series or newer digital SLR cameras, the Quick-Shift Focus System enables manual touch-up focusing after autofocus is achieved.
The smc Pentax-D FA lens mount is called the KAF-mount. This lens mount enables autofocus and autoexposure.