Surveillance technology
I don’t care if somebody steals this - unlike many others, I would rather be happy of seeing this real than dying keeping it under my bed…
So, getting to the point:
To take a picture of everyone on a crowded street, and possibly track a suspect, you would need either more cameras, or a camera with unbelievably high resolution. Neither has been yet created in the size, suitable for the size of a hidden camera.
However, if you pack 10 small cameras in a box, with powerful lenses and really fast turning engines, you get what you need - swift, momentary identification of everybody, at any moment moving in sight of the cameras.
One camera needs just part of a second to take a picture, especially if you have optical zoom - the size of the picture needed is very very small - much smaller than the ones needed to take a picture of a whole street.
So imagine 10 cameras in a box, taking 20 pictures per second - or in other words, single camera being able to identify 20 people per second!
Each small camera will be able to move quickly, guided by software to picture only human faces. It will not waste pixels for filming concrete or cars - just faces. With the advancement of technology (and optics already at perfection), if we combine these we could focus a single IR camera with small enough beam to film only an eye, thus making possible mass iris detection and surveillance. This is literally impossible with the current cameras on the streets.