"Mathew Newton" wrote in message
...
On May 16, 6:39 pm, "George" wrote:

For that particular unit can you see the illuminated LEDs with the
naked eye?

Close up,very faintly...at a distance of 3.5m hardly.

Okay, thanks.

I've read a few articles on the led wavelength and most have said this...
Wavelength
IR LEDs come in various wavelengths, most commonly 940 nm, 880 nm (like the
aforementioned Siemens LEDs), and 840 nm. Which would be best for this
application?

The 840 nm LEDs tend to be barely visible, since their spectral half-width
is wide enough to overlap the extreme red portion of the visible spectrum.
880 nm and 940 nm wouldn't be visible, but they might be too far into the
infrared for the camera - I don't know how fast IR sensitivity drops off.
Obviously, some testing is in order.

So I stayed with the 850nm to be on the safe side of the cameras available
to work with IR night time viewing.

What you have to understand is there's a lot of cameras about that give poor
visabilty at night time and fail with IR because they're of poor design and
low light.

The one I have in the back of the house was gotten from a car boot sale and
is only B&W but its low lux was ideal for the IR lamp and is giving good
results in complete darkness as there is no light whatsoever at the back of
this house.