It is described often as "CCD flare". I'm guessing that between the little microlenses over the pixels on the sensor and the flat spot on the back of the sensor you get a little light that bounces off the sensor, and back off the flat lens element to effectively overexpose that little circle. So the effect may be more noticeable on some sensors rather than others, meaning that you might see it on some cameras and not others. It was never a problem (that I have seen reported) on film cameras.
The good news is that there is probably nothing newly wrong with your lens. Darren -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
