I bought a micro camera to clip onto Fluffy's collar to see what she did all day. The camera was set to take an image every 10 seconds. I managed to capture 9 hours of sleeping cat.
I tried it on her outside. She came back without camera and collar. I never found it.
We had one of these. First day we put it on our dog who roams free during the day (a Cavalier - we live in the countryside). We now have a film of our neighbours kitchen, with the neighbours in pyjamas feeding our dog biscuits. We didn't save the film and we haven't used the camera since....