Lesson 10: Introduction to Flash Photography
Welcome to our introduction to flash photography. In order to learn how to use a flash, it will help a great deal to understand what a flash is and how it works. We’ll cover built-in or pop-up flashes and Speedlight’s or shoe-mount flashes that mount on the top of your camera. We’re going to talk about the different flash units available, how they work, and the advantages and disadvantages of each type of flash. A flash is an indispensable tool and it’s not too complex or difficult to learn.
Why Learn about Flash Photography?
The answer is simple. Learning how to use your flash properly can radically change your photography and will take your images to a whole new level. When using a flash in combination with available light, your goal is to add an appropriate amount of light from the flash to create a properly exposed image. So, it’s helpful to learn how to control the amount light from the flash when working with ambient light. In this lesson we’re going to learn about the various types of flash units on the market, their strengths and weaknesses, and how to select a flash that meets your needs.
Most DSLR cameras have a small built-in or pop-up flash. When your camera is set to fully automatic, it will determine whether there is enough light. If there isn’t enough light, it will pop up the flash automatically.
Most built-in pop-up flashes are located near the camera lens, so the light points directly to the subject. Often this results in red-eye, especially under low-light conditions. Red-eye is common with pop-up flashes because pupils usually dilate when you use a flash in ambient low-light conditions. Red-eye occurs when light from the flash is too fast for the pupil to close, so the bright light from the flash passes into the eye through the pupil, reflects off the fundus in the back of the eye and out through the pupil. The result are subjects with red eyes. The good news is there is a solution! Using a flash source off-camera or from a different angle will help eliminate red-eye.
On-camera flashes, or speedlights, (sometimes called strobe lights), provide additional light when you don’t have enough available light to properly expose your photograph. These shoe-mount flashes mount easily to the top of your camera, or they can be held off-camera using a synch cord. Speedlights run on batteries and the higher end units have an option to connect an external power source for improved performance. Most camera manufacturers offer a range of optional external flash units that are compatible with your specific camera. Most of these units have rotating heads that move left-to-right and up-and-down. So you can bounce the light off a wall or the ceiling.
This is an important consideration with smaller cameras that do not have automatic exposure control, like the two bottom cameras:
Smaller “point-and-shoot” cameras have flashes with non-automatic exposure control and very small flash units. So their range is quite limited. Usually, they are ineffective after 15-20′.
Most serious photographers use flash units with automatic exposure controls (ranging in price from $50 up to hundreds)… typical circuitry (called thyristor circuits) has the ability to continue to pour light onto the subject – and back to the camera – until the exact exposure is accomplished…..
….even if the flash is not pointed directly at the subject matter.
These strobes have a wide range of power settings to use – usually from Full power to 3/4 to 1/2 to 1/4. You can tell what aperture to use by checking the settings dial (r) or, on newer strobes, an LCD Control Panel on the back. Using Full Power drains the battery rapidly so you should normally use a lower setting. I stick with 1/2 power for most work and that is plenty. According to the dial – after I set in the film speed (f400) at the bottom I see that I need to set the sensor on the front of the strobe to red (1/2 power) …. and, RED= f8.0 …. and that is the aperture setting I would use whether I am aiming the strobe straight at the subject or not.
Here is why you would NOT point the flash directly at the subject:
If you shoot “straight- on, you run the risk of washing out skin tones, eliminating texture, creating harsh shadows, and getting “red-eye”.
But, if you want to soften the light and spread it out and eliminate shadows, you should lift the flash off the camera and aim it…. I aimed the flash at the girl in the background and the light spread evenly from foreground to the back. Also, moving the flash to one side will bring out detail and texture of the subject.
Even better…. use “bounce light” whenever possible. By aiming the light upwards it will bounce off the ceiling and spread out softly, giving you much more balanced lighting and no harsh shadows.
There are times outdoors when shadows may require “fill light” from a flash. However, backlit lighting can be pleasing…. here I opened up two stops from the normal daylight exposure.
At other times, outdoors, the shadows maybe intrusive and offensive, and you should use flash to fill in the areas of the subject that are covered with shadows.
Here I had to make the exposure based on the fact that the maximum shutter setting for flash is 1/125th … so I took the flash off automatic – thus giving me full power and set the aperture at f22.
Now let’s take a look at some accessories designed to take the harshness out of flash photography and to help add to your flash techniques….. most of them can be homemade at a considerable savings for those of you on a budget, or very frugal (a euphemism for cheap).
I found this nifty, and very accurate, little Vivitar flash. The trouble was that it had a fixed flash head. So I cut away the upper cover, and re-mounted the flash head inside a black, plastic film canister and secured it with two screws, so that it could swivel. I then added a portion of a translucent film canister to further diffuse the light. It is a perfect, small flash unit with sufficient power for most uses.
The flash on my trusty, old Richoh “point-and-shoot” camera was powerful enough so I placed some Mystic tape over the flash head to reduce the harsh light.
Instead of paying $40-50 for a factory-made diffuser for my Vivitar strobe … I cut off the end of a small plastic bottle (made of translucent material) and taped it on the head. Works great!!!!!
Again, for those of you on a budget, there is no need to kick out $40 for a reflector card…. when you can simply use a piece of white plastic. It works every bit as good as the factory-made options….. and you could use colored plastic to introduce off-colored light!!!
Finally, there are some accessories you should consider buying…. an extension cord (on the left) means you have a high degree of flexibility in the way you aim light…. and a remote sensor (right) that will make a second strobe a slave unit.