Light is the raw material of photography, and understanding it is central to the craft. Natural light comes from the sun and the sky, with the golden hour around sunrise and sunset offering soft, warm illumination that flatters portraits and landscapes alike. In studio or interior settings, photographers often arrange a three-point lighting setup, consisting of a key light that serves as the main source, a fill light that softens shadows on the opposite side of the subject, and a rim or back light that separates the subject from the background by adding a highlight along the edges.
Different light sources emit light with different color temperatures, and cameras interpret those colors through a setting called white balance. Properly adjusted white balance makes whites appear neutral under daylight, tungsten, fluorescent, and other lighting conditions. Photographers can use automatic white balance, preset modes matched to common light sources, or a custom setting measured from a neutral reference in the scene to keep colors accurate or to intentionally create warmer or cooler moods.
When ambient light is insufficient, flash provides controlled artificial illumination. Modern flashes offer TTL, or through-the-lens, metering that automatically adjusts flash power for correct exposure, while manual flash control allows the photographer to dial in a specific power level for use as a main light, fill light, or accent. Beyond flash, another rule of thumb for estimating exposure in daylight is the Sunny 16 rule: on a sunny day, setting the aperture to f/16 and the shutter speed to roughly 1 divided by the ISO, such as ISO 100 with a shutter speed of 1/100 s, generally yields a well-exposed image.
Most cameras offer a range of shooting modes that determine how much of this control is automated. Auto lets the camera choose all settings, while Program (P) allows the camera to balance exposure but permits the photographer to shift the aperture and shutter speed combination. Aperture Priority (Av or A) lets the photographer set the aperture while the camera selects the shutter speed, Shutter Priority (Tv or S) does the reverse, and Manual (M) gives complete control over both. Metering ties these modes together: the camera measures the light in the scene through patterns such as evaluative, center-weighted, or spot metering, each weighing different parts of the frame to decide on exposure. A histogram complements metering by graphing the distribution of tones across the image, with peaks on the left representing shadows, peaks in the middle representing midtones, and peaks on the right representing highlights, allowing photographers to judge exposure more precisely than by looking at the LCD alone.