Is it worth spending extra $1000 on a "D" version of this lens? I heard that the D version is sharper and it has more contrast. Is it true? I have been looking around on the net and so far I didn't find any comparison... I would like to buy a AF 80mm lens for my camera. I have been using manual focus lenses so far and I am wasting a lot of film... My camera doesn't operate with the 80mm LS version. So the LS is out of question. Thanks!