Lighting for refined images
Whether you shoot stills or movies, lighting is the key to creating a mood that effectively conveys your artistic intent. Here we'll introduce a few lighting tools and techniques that you can use to capture professional-quality images.
External flash for greater distance
"Guide Numbers" specify a flash unit's ability to illuminate subjects at a distance. The guide number is equal to the maximum flash-to-subject distance multiplied by the appropriate aperture F-number: Guide Number (GN) = distance (m) x aperture (F-number)
A guide number of 60 (in metres at ISO 100), for example, means that a subject 15 metres away will be properly illuminated with an aperture setting of F4 (60 = 15 x 4). If you decrease the aperture size to F8, the distance will be halved so that subjects at a maximum distance of 7.5 metres (60 = 7.5 x 8) will be properly illuminated. Boosting the camera's ISO setting can produce results similar to using a flash unit with a higher GN.
External flash units
Soften shadows and enhance depth
Although an off-camera flash setup can enhance visual depth, it is usually easier and sometimes just as effective to bounce the light from an on-camera flash unit off a nearby surface such as a wall or ceiling for more natural lighting with enhanced dimensionality. The difference can be dramatic, and since the flash unit stays on the camera, you retain maximum mobility and speed. Bouncing the flash also provides broader coverage, and is ideal when you need to light a group of people, for example.
Aim the flash towards the ceiling to diffuse and spread the light for softer moods and more sophisticated images than can be achieved with direct flash.
You can also bounce off a wall if you want soft shadows that fall to the side of subject contours. This approach can sometimes blend better with indoor lighting.
High-speed and slow flash sync
To create background bokeh in bright light you need a fast shutter speed with a large aperture. If you also need fill flash the maximum shutter speed will be limited, and that can make it impossible to use a large enough aperture. High-speed sync (HSS) makes it possible to use flash at all shutter speeds, so you can increase the aperture as needed.
Slow sync is used in situations where a slow shutter speed is required to properly expose background scenery indoors or at night. The flash fires to expose the subject, and then rather than closing immediately the shutter remains open for long enough to expose the background as well. This gives you well-balanced images in which both the subject and background are properly exposed.
Fill-in flash normally limits shutter speed, requiring a small aperture that keeps the background in focus. HSS allows high shutter speed and large aperture for shallow depth-of-field.
One-light, two-light and three-light setups with ratio control
Multiple off-camera flashes can dramatically expand your lighting options. Ratio control, via infrared or radio communication, can make it easy to achieve ideal light output from each light.
One light: B
Although multiple light setups offer greater versatility, a single off-camera flash can produce beautiful images by moving the main light source away from the camera axis for deeper, more interesting shadows and contours. Reflected light provides some additional fill. The on-camera flash unit (A) is used for control only, while the off-camera flash unit (B) functions as the primary light source for the entire scene.
Two lights: B + C
A two-light setup offers more versatility and control, letting you position the flash units and adjust their output to achieve optimum subject depth with just the right ratio of key to fill lighting. The main "key" light (B) illuminates the subject from the side, while the "fill" light (C) softens shadows and lights up the background. Compared to the one-light setup above, the subject is more clearly defined and distinct from the background. As in the one-light setup, on-camera flash (A) provides control only.
Three lights: B + C + D
Off-Camera Flash Techniques Book
Flash units suitable for off-camera use
Reliable in any light
While infrared control can be disrupted by bright sunlight or other sources that include infrared components, radio control will operate reliably in any lighting conditions.
Work around obstacles
Radio control will work around obstacles that would block infrared control. Receivers can be positioned behind the camera or subject without compromising reliability.
Extra light for better images
Efficient, long-lasting LED lights can provide the extra illumination you need to capture high-quality images. They let you shoot at a lower ISO, and can make focusing easier.
Natural colour balance
Unadjusted LED light is close to natural sunlight, and it's easy to match the colour temperature of other types of lighting for natural colour balance wherever you shoot.