Hi again, Renato - thanks for posting the examples.
Admittedly, I'm somewhat confused. The shot from the Olympus is (with all due respect) worst of the four by far, being defocused or possibly suffering from slight shake, such that the centre of the flower lacks any definition. The shot from the K10D is nice enough, but at f/2.8 the plane of sharp focus is very shallow indeed, so only small parts of the image are sharp. The Nikon Df and Pentax K-3 shots look about equal to me... perhaps a very slight edge to the Nikon, but it's a little difficult to tell as they're different subjects with different backgrounds. Still, I see equally good definition and sharpness in both within the plane of focus. On the K-3 shot, for example, I can see individual hairs on the buds (easier to see if I bump up the brightness on my monitor
). The fact that these last two shots were at f/8 and f/11 has resulted in greater depth of field, so more of the subjects are in focus.
I don't see anything here that suggests the K-3 isn't performing better than your Olympus. I don't think you have anything to worry about
I was a little confused by your following comment:
Originally posted by Renato all the shots are in JPEG , have used RAW with the K3 that of course will not change the IQ any the colour , contrast , exposure etc.
When shooting JPEG, you are at the mercy of the camera's JPEG engine to turn RAW sensor data into a final image. In-camera JPEG engines are OK - some are better than others (Pentax isn't great in this area, in my opinion) - but all are inferior to shooting in RAW and doing the processing yourself in Lightroom, Camera Raw + Photoshop, or even Pentax DCU. The "IQ, colour, contrast, exposure etc." as well as sharpness and noise reduction can all be optimised when you shoot RAW, and you'll get way better quality output this way. If you prefer to shoot JPEG, that's fine - just know that you are missing out on much better IQ as a result.