I am looking for a new lens. My 18-55mm sux! I would like something that replace it. I was thinking maybe something along the lines of 20mm to 100mm, I would like this to be the range after the 1.5x conversion. I need something that is as sharp as my 70-300mm VR. I also need something fast, preferably something that is f2.8 throughout the range. My price limit is $650. I know that I probably won't find exactly what I need in my price limit but there should be something close. Thank you in advance for all your help.