Alex I have and Use a Ridgeline Digital Trail Camera, they are excellent and will capture the smallest critter at a reasonable distant in pitch darkness, you can also do video with it.
There are many different sorts around and you can get them on line easily.
Ours cost just under $200.00.
Put it on a tripod or strap it to a post or tree, they are very sensitive.
We had a noise in the ceiling some time ago and stuck it up roof, and sure enough it was a Rat.
They are great fun.
Leon
