Nitpicking here, but while light passes through a lens slightly more slowly than it does through air, a contact lens wouldn't normally be considered to have stored the Angel's image any more than the air would.

But it does lead to an interesting paradox: does a camera set to record count as an observer in this case? If so, it would seem that its presence should stop the angel from moving.

Or does it only count as an observer if there is a person to notice when it moves...

Are the Weeping Angels monsters ruled by quantum mechanics?

Oh and, responding to the user icon here, that IS a disturbing thought. :)

I think the title is The Time of Angels

You'll enjoy the conclusion next week I think.

Thanks for that, title and content edited to include the new details. :)

As my couple of posts on the subject indicate, there's a lot wrong with these episodes from my PoV.

I haven't read those posts yet (avoiding spoilers) but will do so once I've seen the next episode.