Canon EOS mag

Technique Flash factors

nina bailey nina bailey

Shooting modes and flash The worst possible place for a flash gun

JENNIFER HERSCHBERG brian hall

is on the camera – unless you are balancing the flash with daylight or other ambient light. On-camera flash fires directly at the subject, giving flat,

shadowless illumination. If the flash is the only light source, this is not ideal, especially for portraits. However, if you are combining flash with ambient light, on-camera flash is effective. If the two light sources are correctly balanced, the ambient light provides the light and shade, while the flash lightens some of the deeper shadows to give extra detail without adding a second set of shadows. Most of the images in the article were shot with on-camera flash. Shooting mode The built-in flash provides autoflash exposure metering – either TTL or E-TTL, depending on the camera. It has no manual setting. Flash exposure is automatic, whatever the shooting mode. However, you need to select the shooting mode with care. Program mode (P) The camera sets the shutter speed and the aperture. With the flash activated, the slowest shutter speed that will be set is 1/60 second. Canon says this is to reduce the effects of camera shake – photographers using flash do not expect slow shutter speeds and the need for a tripod. This limit on slow speeds with flash is one of the main reasons the background is dark when using built-in flash – the exposure is not adequate to pick up ambient light from the background. However, despite this downside, program mode is generally simple and effective for flash photography. Shutter-priority (Tv) You select the shutter speed, leaving the camera to set the aperture. Unlike program mode, there is no restriction on the slowest shutter speed you can set, so better background exposure is possible in low light. Use a tripod for slower shutter speeds or camera shake will blur the ambient light exposure. Aperture-priority (Av) You select the aperture and the camera sets the shutter speed. This gives you more control over depth-of-field, but be careful if you set a small aperture. The camera will respond by setting a slow shutter speed. If you do not notice this your ambient light exposure might suffer the effects of camera shake. A tripod is recommended if you use this shooting mode with flash. Manual (Av) You set both the shutter speed and the aperture. This allows you to be creative by over- or underexposing the background in relation to the exposure given to the subject by the flash illumination.

Above Shooting with program mode is likely to give dark backgrounds. The flash exposure for the main subject is fine, but limits set for the shutter speed and ISO value mean that the exposure is unlikely to pick up much ambient light in the background, which will be underexposed. On the other hand, the result is more striking than if there was a lot of distracting background detail. EOS 300D, EF-S 18-55mm f3.5-5.6 at 55mm. 1/60 second at f4, ISO 400.

Below Program shooting mode works well for fill-in flash photography outdoors. The camera is usually able to expose for the ambient light, with the autoflash exposure giving a good balance. There is very little you need to do. Switch to program mode, activate the flash, compose and fire. This point-and-shoot style of photography is good when you want to concentrate on the subject and put them at their ease. EOS 20D, 1/60 second at f5.6, ISO 200, focal length of 42mm.

When shooting with flash you are often taking two images at the same time. One is with ambient light, the second is with flash. This means that you need to remember all the basic rules of photography and then add the rules of flash photography. Flash factors

Ambient light is the key to shooting great flash pictures. Ambient means ‘relating to the immediate surrounds’. In photographic terms, ambient light is the illumination which exists before you arrive on the scene. It can be daylight, tungsten or fluorescent room lighting – even candlelight. If you take pictures by firelight, you are using ambient light. The Canon flash system is designed to take advantage of ambient light. It is only in extremely low light levels that the system reverts to using just flash. You can shoot with a mixture of flash and ambient light at virtually all light levels. This has been made possible by the advances in the noise reduction at the higher ISO settings that are now available. All current EOS cameras are able to shoot up to ISO 12800 – some models go even higher than this. If you shoot in low light situations without taking advantage of the ambient light, then only the flash is lighting the subject. However, unless the background is at a similar distance as the subject, it will be underexposed. This is the cause of the black backgrounds often seen in flash pictures. Balancing the levels between the subject and the background is simply a matter of understanding the relationship between ambient and flash illumination.

Below left and right Ambient light is any light not provided by the photographer. Here it is the daylight coming through a window and the candlelight. The daylight is dull, so the ambient light is flat in the first picture (left). The second image (right) has been enhanced by a Speedlite attached to the camera, using autoflash exposure. The high ISO value has been left unchanged to retain the daylight detail and balance the levels with the flash exposure. EOS 1D Mark II, 1/60 second at f3.5, ISO 1600, focal length 85mm.

Above Here is a good example of balancing daylight with flash illumination. The small inset image shows the result of exposing only for daylight. The main subject is in shadow and all you see is a silhouette. However, attaching a Speedlite to the camera and shooting with autoflash exposure has given an attractive result. The shutter speed and aperture were set in manual mode on the camera, so the only difference is the flash illumination. EOS 1D Mark III, 1/200 second at f8, ISO 100, focal length 105mm.

28 Reproduced from EOS magazine October-December 2012

Reproduced from EOS magazine October-December 2012 29 i t -