Working with Flash
By
William Lulow
Flash, also known as electronic flash
or strobe is a type of light that is produced when an electric current interacts with a gas to produce a short, but intense burst of light. Most of us are familiar with a point-and-shoot camera’s electronic flash because it is built in to the camera. We are familiar with the flash going off and temporarily blinding us while the photo is taken. There are some things about this type of light that are important for serious photographers, be they amateurs or professionals, to keep in mind.
One, flash is, by nature extremely brief. Most pro or prosumer electronic flash units put out light at a speed of approximately 1/600th of a second. Some work faster, some a bit slower.
Two, the intensity of the flash given off by these units is extremely bright. That is to say it is a strong, brief light source. Most electronic flash units, when applied to a subject at a fairly close working distance (say 10 feet or so) actually are brighter than the sun. When you think about it, it makes sense because the sun, although very bright is 93million miles away. So, given the short distance the light from the flash unit has to travel, it is extremely bright. This also means that you can use the sun as an “extra” light, if you will, which can sometimes add some extra “pop” to your outdoor images. Yes, flash can, and in most cases, should be used outdoors to fill-in details in shadow areas of a photograph.
Three, flash is extremely difficult to control. Again, the nature of such a brief, strong burst of light is that it tends to go everywhere. It is therefore, difficult to aim properly.
Four, light from an electronic flash unit or even from a flashbulb, for that matter, tends to lose a great deal of its initial power as the distance to the subject increases. In general, light follows what is known as the “inverse square law.” This, simply stated means that the intensity of the light varies inversely as the square of the distance it travels. If the output of a flash unit gives a reading of f/8 at 10 feet from the subject, it will read f/5.6 at 20 feet. Its intensity will be half as much when the distance is doubled. This is important for pros and advanced amateurs to keep in mind when shooting with flash. The thing that always matters is what is called “lamp-to-subject” distance. The distance the flash is from the subject is the only thing that will control the exposure when electronic flash is being used.
Five, without the ability to preview the effect of a flash, it is almost impossible to predict accurately what its photographic effect will be. Luckily, today with the advent of digital cameras and recording backs, we are able to see the effects of the light immediately. Before digital, most professional photographers used Polaroid Instant Film materials to preview their lighting setups. They would then be able to make adjustments to tweak the lighting to their own specifications for whatever image they were trying to create.
I always tell my lighting students to use regular incandescent or “hot light” before getting involved with flash units so that they can become more familiar with how light behaves. Since light is the main ingredient in all photographs (the word “photograph” literally means “light picture”), it is really necessary to study it if you are serious about improving your image-making skills.
Think of flash as your main source of light whether you are shooting indoors our out. You will achieve superior results if you use a flash unit that can be removed from the camera. If you use a camera’s built-in flash, you limit the quality of the images you can make. Once the flash is off the camera, the possibilities become endless. When you then get into using multiple flash units, then you are beginning to be able to create images rather than simply taking pictures.
