The K-5 was essentially an update of the popular Pentax K-7 which improved the sensor chip, as well as the FPS and video capability.
Improvements over the K-7 were:Edit
- Larger 16.3 Mpix Sony-sourced CMOS Sensor
- New SAFOX IX+ 11 point AF sensor
- Dramatically improved ISO performance with a range from 80-51200 ISO. This is also the largest ISO range of any APS-C DSLR camera, and currently only beaten by three "Pro" cameras by Canon and Nikon (EOS 1D mk4, EOS 1D X and D3s)
- 7 frames per second
- possibly the quietest shutter of any DSLR.