Jesus girl, your photos are excellent. I've never used the bulb option before, but I'll give it a try when I get the chance. At the end of August, my city has fireworks as part of an event called "Kupska noći" (Cup Nights), and every year after the air show, the city puts on a beautiful firework.
!DIY
Try it out.. It is perfect. I googled it out little bit. An it's quite easy. Just need to press that button and release it in right time