I have taken notice that in old digital cameras, special sensors help to target automatically. Those kind of sensors involving some cameras change in contrast, while others make use of a beam of infra-red (IR) light, specifically in low lumination. Higher specs cameras at times use a mixture of both devices and likely have Face Priority AF where the digicam can 'See' the face while keeping your focus only upon that. Many thanks for sharing your notions on this site. http://www.hghreleaserreview.com