I want a lens that I can put a 1.4TC on that will get me to 400mm and sharp enough to crop in alittle. I just tried out an adapted Tokina 150-500 F5.6 and lets just say I didn't need to go to the gym after lugging that and my tripod through a couple of hikes...Here's what Wanted to keep the price around $500. Here's what I've found... Four Thirds Panny 100-300 Oly 70 - 300 I've owned the Oly and sold it. I wishi I would've kept it. Is the Panny a better lens...ie sharper? Or...would you just get the newer u43 and crop? Or...is there a zoom of any brand that is renowned for being really sharp yet somewhat inexpensive?