"Clarity and color is amazing in low light situations. Also depth of field is amazingly tight at 1.4. I haven't had problems with the autofocus speed. For the price this lens is amazing." bhphotovideo.com
"I've owned this lens for two weeks and couldn't be happier. I've shot images of dogs running full speed and the focus keeps up with them. I've also shot some humans at 150mm @1/30th sec. and they are as sharp as could be. I am 100% happy with this lens." bhphotovideo.com