There have been several threads at PF about trying to minimise the JPEG file sizes. There are basically two methods: (a) reducing the pixel resolution (eg 12 => 6 Mp), and (b) changing the JPEG quality (from 4 stars to 1 star).
With the K-7, I made some simple tests and I read several other threads fo K-7 cameras. The outcome was simple. The method (b) gives the
best output for an identical file size. In other words, change first your JPEG settings from 4 down to 1 stars. Then and only then, if you need smaller filesize, consider to reduce the pixel resolution.
I understand that the quality JPEG files drop sharply when the files need to be re-sized from the origial sensor size to a small size: eg from 12 Mp to 6 Mp in your case.
With my K-7, I shoot 14Mp two stars (instead of 4 stars). If I want smaller file, I would switch to 1 star but retain 14 Mp. (The K-7 sensor is 14 Mp resolution.)
Food for thoughts and hope that the comment may help.....
Last edited by hcc; 02-23-2012 at 10:19 PM.