I am going to do some firework shot tonite. There isn't any good background where the firework is going to be so I will shoot the fireworks only. Last time I use f/8 for ISO 200 color negative film and it seems overexposed. I could print them down but I would like to reduce exposure this time but definitely not underexposure. May f/11? Any thought? It seems the exposure time about 1 to 3 secs is what would capture the pattern I want.