In message ,
RustyCrampon wrote

I've got a B&W CCTV bullet camera which claims a sensitivity of
0.005lux, but in reality it can't see much.

Is that the camera body spec or the combined lens plus camera spec? Does
the camera need a f0.7 lens to achieve the low light performance. The
lens supplied, as standard, may be the cheapest compromise specification
and unsuited for low light performance.

Can you easily see someone in the field in full daylight or does the
camera resolution and lens field of view limit the intruder detection
ability.

0.002 lux is equivalent to a clear moonlight night - see the table on
Wiki at http://en.wikipedia.org/wiki/Lux.

In the past I haven't found to many visible cameras with a night-time
performance specified better than 0.002/0.005 lux. When in this night
time mode they probably don't have the "headline" detector resolution
and require a more expensive lens.
--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk