Further to what our die-hard Pentaxian Mr. Mouse at the DPR forum reported last time, yet another K-5 user elsewhere has found the same, that is, the sensor "stains" on the K-5 sensor could actually develop and accumulate over time! See the following latest report, with a latest "UFO" image by his unit included:-http://www.dchome.net/viewthread.php?tid=999546&extra=page%3D1(in Chinese, Google