Among the various improvements brought to autofocus technology over the years, I consider eye detection one of the most interesting. Why is this?
Well, the explanation is quite simple: when you take a picture of a person, achieving correct focus on the eyes is essential. If the eyes are out of focus, even just slightly, part of the identity of the person being photographed can’t be read and as a consequence, the emotional connection the eyes transmit is lost. Of course there can be exceptions if the photographer is trying to communicate a specific message, but the general rule is that a good portrait must have the eyes in focus.