“ I have noticed that in digital cameras, specialized sensors help to focus automatically.
Those kind of sensors involving some cams change in contrast, while others make use of
a beam associated with infra-red (IR) light, specially in low lumination. Higher standards cameras often use a mixture of both
systems and probably have Face Priority AF where the dslr camera can 'See' your face while keeping focused only on that.
Thank you for sharing your thinking on this blog site. ”