So I tried out some firework-photography and though the rocketshots weren't that good because I used only a 18-50 at that time the other shots made from the busters and fountains made with my new 70-300 were usable.
So have a look:
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Buster at explosion
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Fountain
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Jumper
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"Roman Lightings"
All made with EOS 350 D at ISO 100 and around 1 second shutter time.