Lighting with a Flash
Another great article by Riaan Roux
A flash, strobe or speedlight are basically all the same thing and produce strong light for short bursts in sync with your camera shutter to capture a photo. Flashes come in three main varieties, built into camera (or pop-up), flash unit (fits on camera) and studio flash (or strobe). I will attempt to explain how using a flash to light your subject will affect the appearance of your images. Studio strobes and flash units do not differ very much and produce very much the same light (for higher end flash units). Studio strobes are generally cheaper per unit than camera flash units, but you lack the portability as studio strobes require power outlets (and a pain to lug around). Photographers who, like myself, use flashes extensively in their photography are referred to as strobists.
Below is a series of images taken to show how flash lighting affects the subject.
The pop-up or built in flash is horrible and there only as an emergency light source or people content with snapshots. A professional photographer will very rarely use a pop-up flash as it is mostly uncontrollable. Some professional cameras are not even fitted with a pop-up flash. When you do see a professional photographer using a pop-up flash it will usually be to trigger off-camera flash units which are signalled to fire by the light signalled from pop-up flash. In such a case the pop-up flash does not contribute to the lighting of the scene but merely send a type of Morse-Code to the other flash units. Pop-up flashes have a very short range (about 5 or 6 feet) and also create harsh shadows in the background (see above example). The subject is usually also flattened by the light and it tends to create hot-spots of light on your subject when closer to the camera. When the subject is a little further from your camera, pop-up flashes tend to under-expose the subject. Outdoors, when light is fading or when in shadow, a pop-up flash can be used to fill-in some light, but a pop-up flash should not be used as the only light source if you intend to do professional photography.
On Camera Flash
A on-camera flash is a step up, but hardly makes for professional photos when constantly pointed at your subjects. An on-camera flashes pointed at a subject produces only good looking snapshots which are OK for the hobby photographer. On-camera flash units are normally fitted with a diffuser panel to soften the light a little and thus creates softer background shadows (see example above). On-camera flashes still flatten features of a subject by killing all shadows on features facing the lens. Shadows are your friend when you learn to control light and, when dropped to the sides, they create depth and dimension to your photos. When professional photographers use an on-camera flash they will do so only to fill in shadow areas without lighting too much (killing the shadows).
Your flash is still on your camera, but now you tilt it up to the ceiling or towards a wall or other white surface and bounce the light. Bounced flash, as in the example above requires a ceiling, wall or other white surface from which the light of the on-camera flash can be bounced. This give a more natural look and feel to photos, but it does have its own drawback in that it is tricky to learn to bounce the light correctly without adding unwanted spectral light. Some flash units are fitted with a bounce card (white piece of plastic which pulls out behind the flash head) which can be used as a bounce surface when no other surface is available (like outside or building with very high ceiling). The bounce card can also be used even if you use a ceiling or wall to bounce light to allow more light to be directed forward, but this should be experimented with extensively to learn to apply correctly and avoid the “snapshot” look. The biggest advantage of bounced flash light is that you effectively kill distracting background shadows. The disadvantage is that your flash light will pick up any colour from the surface it is bouncing from and add it to your subject. If you have a red surface you subject will get a red cast. Bouncing also requires that your flash work twice as hard producing the light as it needs to travel further and this will eat your batteries.
If you use a flash unit on a stand triggered by a wireless transmitter (radio or optical) then you start to enter the world of professional photography. You can now control how much light you want on your subject and how much shadow you want to create to enhance features or create depth. You can also start to use light modifiers to soften or enhance the light. In the above examples a flash unit to the left was used first with just its diffusion panel and then with a silver umbrella (also known as a broli or brolly). There are many types of light modifiers from beauty dishes, soft boxes, grids, snoots and umbrellas (reflective or shoot-through) which you can use. In the above example the silver umbrella produces a slightly more pronounced light adding a look of drama to the subject.
But lighting with a flash does not stop there. In the above examples the background is actually supposed to be white, so why is it greyish? Well, the simple answer is that the background is not getting enough light. Without getting into the technicalities of the inverse-sqaure law of light which explains why light drops off three times as fast for every double in distance, just accept that the light you are providing for your subject is never going to be enough to light up a background as well when it is further from your subject. If you attempt to light the background and subject with just one flash unit your subject will always become serious over-exposed (unless the subject is standing against the background). To make a background white you need another flash unit (or even two depending on the evenness of light you need). In the second-last image just 2 flash units were used which is already producing a professional looking photo, but it does not stop here. The shadow side of the subject has a dark look to it and pulls focus towards the light. To balance this we add a 3rd flash unit to create a rim light on the right of the subject. The darkness has been lit up and the light focus is now centred on the subject. Study more images in magazines, on the internet and even in television programs and note how many (if not most) have this sneaky rim light somewhere on a edge of a subject just to give it that little balance.
In the professional photographers’ kit you will always find a high quality flash unit, and a professional strobist will always have 2, or 3 or 4. I never leave home without at least 3 flash units in my kit bag. Flash units are expensive, at a cost of R3000-R4000 each for higher end units, but once you learn to control light with multiple units you find it hard to turn back.
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