Below are five pictures of fireworks taken around the northeastern part of Tucson AZ, near the foothills.  I've included one extra full-res shot at the bottom of the page (with additional compression for quicker download) so you can check out how a bad lens can make a fireworks picture look even better. 

All shots were taken at F/7.1 and ISO 100 with shutter speeds around 3-4 seconds.  Lens used is the Sony 75-300mm F/4.5-5.6 where it was at or near the 300mm mark.  Also, I've cropped all but the last picture.  Actual distance to fireworks, roughly 2.5 miles or 4 kilometers.  Some of the bursts have cork-screw trails, it looks like a bad compression job---but not in this case.

The last two pics are to show the effects of Chromatic aberrations.  In this case, it's mostly blue (look along the white trail on the right and the blue in the burst itself)  There's some blue that's supposed to be there but it's enhanced with the CA.  You can also see some purple in the center of the lower left burst.