On Tue, 21 Oct 2014 09:54:34 GMT
DerbyBorn wrote:

I have noticed many CCTV cameras have a ring of LEDs around the lens
- but behind a front glass (Saw this on a drone which made me
wonder....) Can the LEDs be of any use given the sort of useful
distance that the camera is expected to focus on? Does having the
LEDs behind the front glass cause scatter off dust and moisture to
ruin the image. Are they just a gimmick?
(a bit like using a flash on a camera at a stadium concert - see
Inverse Square Law of Light)

The built-in LEDs don't suffer from scatter, as described in another
post, but if you put the camera behind a pane of glass, then you will
see nothing using the LEDs, it will just reflect off the inside of the
window.
I have a camera in my two-car garage, and with the built-in
LEDs, I can tell that there is a car on the far side of it, or not, but
there is no detail. Much better than flash at a concert, no question.

--
Davey.