Tamron SP300 2.8 + 1.7AFA K10

Hi all
Last year I purchased the K10 to use on this lens combination having previously used it on my Ds and been very pleased with the restuls. I have been disappointed with the amount of ca in the images taken with the K10 in comparison to the Ds. I have been very pleased with other lenses used on the K10. I have considered trading the K10 for a K20, the theory being the cmos sensor may produce less ca than the ccd on the K10. An expensive experiment I know, so I wondered if anyone out there has experience of this combination or any comments/thoughts would be appreicated.

Thanks, mxds