"Is there any difference between these 2 lenses other than the price and f-stop? This is a common question that pops up frequently on forums everywhere. While the general consensus is that these 2 lenses are almost identically sharp, there are other factors that have not been fully explained or readily available. And there are lots of wordy discussions but hardly any picture to illustrate. Since I happened to have a new f1.4 together with my old f1.8, I decided to do some tests to find out the answers myself. My test is focused on more apparent difference at wide aperture rather than trying to find out split hair difference."