To all who responded on my question about sensor quality of Canon vs. Pentax, Sony and Nikon: Thank you for your responses. I didn't expect to have so many make negative comments about DxOMark, especially when I didn't mention it by name. I think the best response from my point of view is the one from Laurentiu. Those who bash the DxOMark testing have not, to my knowledge, suggested an alternative. Does anyone know of any other testing organization that attempts to make similar tests, but does so with more general approval? I have never appreciated comments like "tack sharp". I am more analytical by nature, so the DxOMark service appeals to me. And I look at lens tests to make choices on lenses. I am fully aware that there are many other feature issues that must be considered in making a decision on which camera to buy. I started with the sensor issue, because as a film photographer for several decades, it is the most obvious feature that I look at. I have never owned or used a digital camera! But I plan on buying one this year. I will be using it for pictures of people and some use in astrophotography. Perhaps eventually using it for landscape as well. Of course I should buy a full-frame or larger, but I don't wish to spend the required higher cost at this time. I do landscape photography in prints as large as 24x36. With film cameras from 35mm to 4x5, I have never had to choose a camera based on sensor limits. So this is a new experience for me. It is from that perspective that I asked the question. Maybe I should start with a cell phone camera! (just joking) Again, thank you all for your thoughts.