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A good example of reflected light.In photography, there are two types of light: reflected light, meaning light that is reflected by your subject; and incident light, meaning light that falls on your subject. Digital cameras usually have built-in meters that measure reflected light. Some also have the capability to measure incident light. For greater exposure possibilities and more creative use of light, you may choose to use a handheld light meter to determine what exposure, white balance, color temperature and contrast settings to use. -
The main function of your digital camera's lens is to collect light or expose your camera's sensor to the scene you are photographing. Shutter speed and aperture are exposure settings. In digital photography, shutter speed refers to the length of time (in seconds) your camera's sensor sees the scene you are photographing, as opposed to how long your film was exposed to light in film photography. The higher the shutter speed (for example, 1/1000), the less time the sensor sees the scene.
The aperture is the diameter of the opening of your lens. It determines how much light is allowed to pass through the lens. Choose a smaller aperture value (for example, f/2), and the opening will be larger, allowing more light to pass through the lens. Choose a larger f/stop (for example, f/16), and the opening is smaller, allowing less light to reach your sensor. - The ISO setting on your camera used to refer to film speed. In digital photography, ISO sensitivity determines how much light is needed to get a good exposure. For example, the higher the ISO sensitivity, the less light you need; therefore, you can set your camera to a higher shutter speed or larger f/stop (smaller aperture opening) in order to get the desired result. Most digital cameras also feature exposure compensation dials you can use to manipulate the light, making your image brighter or darker.
- The color of your subject can be affected by the color of a light source, such as incandescent or ambient light, which may cast an amber or yellow glow onto your subject. Fluorescent lighting may cast a green-bluish glow onto your subject. Most digital cameras feature the following white balance presets: incandescent, fluorescent, daylight or sunlight, flash, cloudy and shade. Setting your white balance to the appropriate setting will offset any negative effects of the existing light and ensure the color of your subject is not affected by the light source.
- Under the white balance setting, digital cameras, such as the Nikon D90, also allow you to fine tune white balance by adjusting color temperature, which is defined by Nikon as "the objective measure of the color of a light source." Our eyes see a white object as white regardless of the light temperature. Digital cameras have built-in color filters and register the level of each color of light, especially white, based on how the camera sees it through those filters, according to David Cardinal in the book "The D1 Generation."
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An example of high dynamic range.According to Freeman, dynamic range is defined as the ratio of the brightest tone to the darkest and is "an essential feature of the light in any scene." He adds, "Most exposure and capture problems arise because of too high a dynamic range," says Freeman. "Very high dynamic range scenes are those that include the light source." For example, you may shoot a photo of a person on the beach in daylight. Your light source is not only the sun but also the light reflected off the water or the sand. Most digital cameras feature a LCD histogram or graph that displays brightness levels in your scene. For example, if tones are clumped together in the center of the graph, this indicates a low dynamic range. -
Fill-flash illuminates the subject in this imageUse fill flash to change the brightness of your subject in relationship to the background in your image. Most digital cameras now feature flash compensation settings, which allow you to increase or decrease the light output from your flash. For example, some digital SLRs have a night flash setting. You can use this setting to reduce contrast between your subject and the background. "A digital camera meters the results of a flash over multiple spots across the image area, compares those readings, and then calculates an exposure," says photographer Rob Sheppard in his book "Digital Photography Simplified." Your in-camera flash will not be effective if your subject is more than 10 feet away. Attach an accessory flash to your camera to get better light output. Accessory flashes will allow you to bounce the light, thus reducing harsh shadows and red-eye.
