I took this picture at the zoo (cropped at 100%) using a Nikon 70-200mm zoom and a Fuji S1 Pro. As you can see, the picture is a bit soft and not as sharp as I would like. Shot was handheld, 1/300 sec, f/5.3, ISO320, focal length 188mm, EV -1.
Is it because I had to set a faster shutter speed? In general, what shutter speed should I use in zoom situations when I don't have a tripod?