The first efforts I made were not good: Many photographs taken were useless (they were mainly whiteouts), because the camera is too sensitive and the night lights too bright for the close work needed indoors.
So thinking this through, I worked out that to get sensible pictures I needed to adjust the camera to reduce its sensitivity to get the results I wanted. Now as this unit is essentially a 'sealed unit' (it's protected against the elements) it does not have many controls you can access like a normal camera. Therefore, I couldn't actually alter the camera settings. What next? Well, the only thing left is to reduce the light emitted by the nightlight (the 15x IR LED's fitted to the camera shown here on the lower half of the camera)
This turned out to be easier than you might think. All you need to do is to fix a filter to the front of the camera covering the IR LED's and that's it; Job done. Well, almost. You need to find the right filter. I estimated that I needed to reduce the amount of IR light to about 10% of its original value and to achieve this I had to choose a good filter. As I am an engineer with computing tendencies, I have a number of anti-static bags around that are used to protect sensitive electronic components such as memory chips and hard drives. These are made of silvered plastic and are almost opaque.
I tried one of these on the front of the camera held in place with an elastic band ...
... and the results were just what I wanted. Now all I need to do is make the mouse stand still long enough for a clear picture.