Sony Ericsson Xperia Arc

I have noticed that in uwtnnaed cameras, extraordinary sensors help to maintain focus automatically. The sensors associated with some cameras change in contrast, while others utilize a beam involving infra-red (IR) light, specially in low light. Higher spec cameras sometimes use a blend of both systems and probably have Face Priority AF where the dslr camera can See' a face and focus only in that. Thank you for sharing your thinking on this blog site.