Ice Skating - Dragging the Shutter

I had the opportunity to travel to New York City and (as I often do), found myself at Rockefeller Center around midnight.  I had my Panasonic Lumix GF1 with 20mm F1.7 fixed lens.  I decided to try to get the ice skaters in motion while panning the camera.  I took around 50 shots at varying shutter speeds.  No flash was used.  These are my favorites.

 

1/5 Sec, F5.6

 

1/5 Sec, F6.3

 

 1/5 Sec, F5.6

 

 

1/5 Sec, F5.6