On 18/11/2019 22:33, T i m wrote:
Hi all,

I was looking into a very basic domestic CCTV solution. I already have
a variety of gear to play with (old cameras, external enclosures,
DVR's etc) but am specifically interested in the very low light
cameras.

I believe some here have mentioned the NiteDevil range but reading
around seems to suggest that these sort of low light cameras (as
opposed to high-end / military I suspect) achieve such with fairly
long shutter times and so are prone to blurring / smearing on any
moving objects?


The sensors in digital cameras/phones can see IR up to around 1.1um
although most may have a filter to exclude the near IR band. Point your
phone camera at the output of your TV remote and press any button and
probably you will see the IR LED flashing. Iphones may have a IR filter
on the back camera but possibly not on the front camera.

Military IR cameras operate in the 3um to 5um band or the 8 to 12/14um
band. Cameras fitted to the police helicopters are probably the latter.
With these cameras no additional illumination is required. These cameras
do not have glass lenses because glass blocks the IR in these bands.

The domestic CCTV cameras you can buy will be optimised for the visible
band but have response into the near IR band (1.1um). IR has no colour
hence B&W video output. So basically you are operating the camera just
outside the visible band and in low light hence longer exposure times,
frame to frame integration over a period of time or additional
illumination (in the IR band)


If you have an old digital camera and you want to experiment
https://www.instructables.com/id/inf...-the-real-way/

or

https://tinyurl.com/wdu4oey

Try it on a very cheap web cam.

If you have any processed colour film negatives around the bits at the
end that are completely black can be used as the filter instead of of
the Congo Blue filters mentioned in the above article. You could use two
bits(double thickness) of this black negative as a stronger filter.


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