I have a fairly new K-30 with a relatively old 18-55 kit lens I got with a *ist-dl a while ago. I don't have any other lenses to test with at the moment, waiting for delivery of another. I have a funny round blur about 1/4 of the way down from the top and just left of center. It looks like something out of focus, but I think if it were on the lens it would just affect the IQ not actually show up. But if it's out of focus, it can't be the sensor... Hmmm.
Would someone give their opinion on the aberration visible on the attached images of a grey sky? If you flip through them you can see it more easily.