qingtian,
I agree with some guys comments on diffraction. Shooting at min aperture doesn't mean your pics will turn out sharp. The word "sharp" is argueable bcoz some ppl like it VERY sharp,some ppl just like it sharp so long as u can see the building. Some ppl are addicted to sharpen their pics so much that the human's face (after processing) is overkill. There's a prob call atmospheric haze which u can never get it off unless u shoot in very dry condition like in Europe,Northern Japan,Russia,etc. Btw 17-40 (in my opinion) is not really a sharp lens. Sharp lens is best to be fixed focal length eg. lens by Leica (ASPH) & Zeiss (Distagon series). Try shooting fr the same scene with 16-35mm L Mark II. All the best.
Agreed on the too much of sharping on human face...
Most of my cityscape and landscape shots which I took, I will do some basic sharping.
However I do not have any habit to sharpen human/portrait shots as it indeed look a bit un-natural to me.
Hmmm... only one question here leh, where got '2 questions'?:bsmilie:
Anyway, to my humble knowledge, sharpness has everything to do with the lens setting. Not with the camera body setting.
The only setting remotely linked to your camera is that built-in 'Sharpness' parameter in 'Picture Style' of our Canon camera. But as a general rule, don't touch that one first until you have a better grasp of the principles of lenses.
Lol, there is 2, the 2nd questions is I just want to be sure that problems lies with the human (me) on the camera setting instead of a lemon 7D body that everyone else is discussing about...
Understood on the picture style thingy!