All Pentax K mount optics will work on the digital (or film) Pentax cameras. The regular Pentax K optics will work in ONLY the manual mode on Pentax K mount digital cameras. This means you set the f stops. Very hard. The A series K mount optics will work in both the manual mode and any automatic modes that your camera has. So both types of lenses work but the A series K mount lens is fully designed for the Pentax digital cameras.