Nothing to do with the paranormal, but I can certainly relate to Negative's comments on photography.

I would comment that you get two influencing factors, particularly with small, automatic digital cameras.

Firstly, with a low shutter speed things get blurred and point sources of light will tend to "string". The second factor is that in low light conditions, the aperture opens fully.

Depending on the angle at which the light enters the lens, you can get reflections from the surfaces of the internal lens elements. This will typically show up as an "orb" and, given a bit of camera shake due to the slow shutter speed, this is frequently blurred enough to hide the outline of the shutter.

If you look in a professional photographer's kit you will see a number of lenshoods, that are designed to help avoid this effect.

Faces in windows? well I have seen plenty of those in photographs........ glass reflects, particularly if it is dark behind it