Photography - Light/Polarisation

[Satori_001]

A friend of mine recently took some photos in Paris at night of the sites. Using a slow shutter speed (8secs) on a Panasonic Lumix FZ5. In some of the photos (at distance) you can see trails of lights from cars which are apparently moving in a spiral motion, increasing in amplitude the further from the source (car) they get? Visible from both moving cars and still traffic lights, perpendicular to the camera.

Someone please explain?

Many thanks!

[Teddio]

Presumable with an 8 second exposure your friend was using a tripod. It is likely the camera was moving slightly thus trailing the images into a spiral.

[mibn2cweus]

I've seen peculier spirals in photos where the camera was proped against a car with the motor running.

[Mortartube]

What lens was used? Some long focus lenses contain a mirror which can produce odd effects, i.e circles on highlights on breaking waves etc.