Originally posted by aurele Yes, the k-x is better. especially in Iso perf.
for jpeg, is suggest you to increase a bit the NR done by the K-x (if i remember well : menu/C2/14/strong.)
The factory default for the K-x is Medium starting at ISO 800, This produces a plasticky look that I detest, Strong would be even uglier. I use the lowest setting for noise reduction, starting at ISO 1600. If I need more NR, I use Noiseware, which doesn't produce an overly smooth texture. I often wonder if the amazingly better ISO performance that people attribute to the K-x is mostly due to the excessive processing done by the camera. The factory default for the K20D is NR off. I tested my K-x and K20D with NR off. The K-x has more noise at ISO 3200 than the K20D has at ISO 1600, so I make the actual difference 2/3 of a stop.
As far as which has better IQ, it depends on what you mean by IQ and it depends on personal preference. The K-x wins at very high ISO. The K20D has better white balance in daylight, the K-x has better white balance in tungsten light. The K-x has wider dynamic range, which can be important if you push your files a lot in post-processing (I rarely do). The K20 has slightly more resolution. I prefer the look of K20D images because it produces deeper looking colours. When I try to bump up the saturation in the K-x, red and yellow start to bloom. The K20D exposes more accurately, which factors into IQ. For some, the increased dynamic range and higher sensitivity mean the K-x wins for IQ. I have different priorities and preferences, and I prefer the look of K20D files at any ISO below 3200. Coupled with the radically improved controls of the K20D, I use the K20D as my main camera.
The K10 has excellent IQ at base ISO, some say the best of these three, but falls behind in low light. I avoided the K10 because of so many reports of back and front focus. The K20D has AF adjust for each individual lens.