I want to ask a simple but general philosophical question? Do i have to do Post Processing after taking pictures? At what level it is acceptable? I mean is it a correct idea playing with the nature of a photo?

I am computer world so i am sure that i can learn PS or other PP programs. But, although i have been in digital photo wolrld for 5 years i have never applied PP for my pictures. My aim is to take pictures with right values (exposures, etc.) so that there shold be no PP needed. Is it possible?

I see PP done pictures and they look artifical. But when i send my photos to some forums they say that "oh no you should have processed it. There are some errors in the photo (lets say that contrast errors, overexposed parts,etc. ) .

I need your thoughts.