It is largely accepted that the Chinese invented fireworks. During the Sung Dynasty (969-1279), a cook discovered that mixing sulphur, saltpetre, and charcoal was a highly explosive cocktail if packed into a confined space. At first the discovery was used as a means of entertainment but was soon adapted for warfare, firing rocket-powered arrows. Over the ensuing centuries, this technology spread across the globe, eventually reaching Europe in the 13th century and with the subsequent invention of the gun in the 14th century. But it wasn’t until the 19th century that fireworks took on their more colourful side. Various colours were achieved by mixing potassium chlorate and various metallic salts: strontium burns red; copper makes blue; barium glows green; and sodium produces yellow. Magnesium, aluminium and titanium give off white sparkles or a flash. Next time you watch a firework display, spare a thought for the pyrotechnical skill involved in the relationships between vectors, velocities, projectiles and their trajectories together with the explosive forces behind those pretty burst patterns.
Photographing fireworks also needs skill. Firework displays only take place occasionally and so practice is limited. Nevertheless, you can keep your eyes open for events involving displays and also request information on them. A firework display is usually watched by a crowd of people, which means that either your tripod gets in the way of others or gets jogged, thus spoiling your shot. However, as the action takes place high in the air, you can usually find a suitable shooting place at the back of the crowd. Get there early and choose a good vantage point. One problem with photographing fireworks is not knowing where to point the camera on the tripod. You don’t know how high the rockets will fly, so it’s difficult to know how to frame your shot. Handheld is of course easier but you won’t get a sharply focused image because of the slow shutter speed. The finale is usually quite wide and high, adding to the problem. So how do you go about getting good shots?
Firstly you need a tripod and a cable release. Use a wide-angle lens or at least a standard lens to cover as much sky as possible. You can use a telephoto lens, but this means you have to be more accurate when shooting off a tripod. Also, the longer the lens length, the faster the shutter speed required (e.g. a lens length of 200mm requires a shutter speed of 1/200 sec.). Use a low ISO; using a high ISO may make shooting easier because you have a faster shutter speed, but the quality of the image will suffer. Turn off the auto-flash – it won’t help for distant shots. Set the focus to infinity (via manual mode). Set the aperture to about f/8. Wait until you see a rocket climbing or feel that a burst is imminent and open the shutter on bulb mode. Leave it open for anything between 4 to 20 seconds, until that particular display ends. It’s impossible to predict things to perfection, so be prepared to shoot plenty of images.
If you have some good shots you can also copy these onto another night-time photograph.
Here’s how in Photoshop: open a firework shot with a black sky. Select it approximately with the lasso tool and include some sky. Choose edit – copy. Click on the night-time shot and choose edit – paste. You should now have your firework shot(s) added to your night-time shot. Go to the layers palette and click normal in the submenu and choose lighten. Your firework shot should now blend in perfectly and can be moved (move tool) and the size changed (Ctrl and T holding down shift to retain the proportions).