Well, i do have a fair share of terrible experience as well. This guy tried my lens using my camera body. Out of goodwill i agreed to loan it to him. He seems very pleased with the results on F2.8; mentioning it was very sharp, later moving on to f4, he say nt sharp. And tts like after 4X of shutter. I was like giving him the o.O look. after that he still very buay pai seh, continue testing for another 5X shots. Then say, no the lens nt sharp at f4, so i nt buying it. I was like WTH, you wasted like 2hrs of my time, plus abt 100 of my shutter. And he just said, no, not buying oso no saying of sorry.