Originally posted by TheOneAndOnlyJH I've never had a K-5, but I can say that the K-3 really does exaggerate any flaws if you zoom in at 100%. If you're concerned, try re-sizing the K-3 images to 16MP to compare against your K-5 pics. I think this is an issue of the high resolution of the K-3 allowing you to look at your lenses more critically.
+1
The only other thing I'd mention - in case you haven't already considered this - is to ensure you have calibrated the lens with your K3 using AF fine adjust. It's just possible that you were getting more accurate AF with the lens on your K5IIs, so it's worth running some tests to make sure that lens with your K3 is fine adjusted. It can make the world of difference, particularly at wider apertures and closer distances where the depth of field is shallower.