I looked at the lens section of this site. But the MTF concept is too complicated for me to understand. I downloaded some MTF charts from http://www.zeiss.com website. I try to compare the MTF between 80 CB and 80 CFE. Could you explain what is the ideal curve (diagram 1 and 2, k=2.8, k=5.6) in this case and from the curve, could you tell approximately how much better is the 80 CFE lens? I know that a purchasing decision based on MTF is not good. But just want to know something basic about MTF since the information is available there. Thanks!