On Fri, 17 Apr 2015 22:03:59 +0100, "Gareth Magennis"
wrote:



"Michael Black" wrote in message
news:alpine.LNX.2.02.1504171552140.20316@darkstar .example.org...

On Fri, 17 Apr 2015, Dave Platt wrote:

In article ,
Pat wrote:

Back to the original question, most of the newer cameras have an IR
filter to keep daytime IR light from fuzzing up the picture. If the
camera has nighttime IR illumination, then that filter is turned off
at night so your IR scheme would work at night.

If that's the case, then I suspect that a bunch of high-output narrow-
dispersion IR LEDs, aimed in the direction of the camera, and driven
with periodic high-current pulses, might be the way to go. Think "IR
flash". You can get significantly higher peak intensity from LEDs by
pulsing them - their peak-current capacity is higher than their
continuous-current capacity.

Camera sensors tend to have some "memory", and so if "blinded" by a
bright flash they'll take a fraction of a second (or more) to recover,
just as human eyes do.

Strobing a bank of IR LEDs several times a second might "give 'em
fits".

If you really want to get cute, build a sizable panel of IR LEDs in a
rectangular layout with individual drivers (e.g. one transistor per
LED, or row-and-column drivers), hook it up to a PC or single-board
computer through a suitable interface, and write some software which
"strobes" a message across it.

"STOP SPYING ON US!"

It'd be invisible to the eye, but visible to the camera.




Maybe it's just a paranoid interpretation of it all.

I had to read the original post a few times to follow who was doing what.

In the end, are we sure the guy with the camera is spying on the backyard,
or is he outright spying on the bathroom?

Michael




I think to reach any conclusion at all on this matter, you would need to
hear from the other party to find out why they are doing what they are
doing.

IMHO it is very dangerous to come to any conclusion at all based upon one
aggrieved parties's testament.
Why would you do that?

Because it's all we have and we need something to talk about on a Friday
evening.


Gareth.