Everything you need to know about Exposure

Finding the optimum exposure for your subject requires balancing technical considerations and creative intent to arrive at an exposure that best portrays your subject. Here is what you need to know.

Exposure can be tricky as it has technical considerations and is also subjective depending on the photographer’s intentions when portraying a subject. Camera meters look to balance out the brightness range of a scene from the darkest element to the brightest. As photographers, we need to expose the scene based on the lighting and our photographic intent.

• Understanding the Exposure triangle: The exposure triangle relates to the relationship between aperture, shutter-speed and ISO.
  • Aperture: Pertains to the amount of light coming through the lens. Small apertures (large F-stops) let less light in, Large apertures (small F-stops) let more light in.
  • Shutter-speed: Shutter-speed regulates how long a camera sensor or analogue film is expsoed to the light coming through the lens.
  • ISO: ISO sets the relative sensitivity of the camera’s image sensor to light, with analogue film photography, film has a ‘given ISO’ that cannot be changed. Lower ISO settings provide cleaner images and in digital photography low ISO settings also help render more detail from the shadows to the highlights (dynamic range). Higher ISO settings are used in low-light environments to boost shutter speed and aperture settings. Higher ISO settings can also be helpful when you need to use fast shutter speeds for action photography.
• Metering: The brightness of a scene is measured by the camera’s built-in lightmeter and the camera sets a base exposure according to the camera mode in use.
• Histogram: Camera Histograms show the distribution of tones in an image and help you assess exposure, darker tones are to the left, brighter tones to the right and mid-tones are in the middle of the histogram. Histograms can help warn of over or underexposure or when the brightness range of a scene exceeds the dynamic range of a camera sensor.
• Exposure compensation: When using full auto or semi-auto modes, exposure compensation allows you to adjust your exposure by decreasing or increasing the exposure value suggested by the camera’s meter. This is useful in tricky lighting situations or when the recommended exposure value does not work for your subject.
• Bracketing: In difficult lighting conditions or when the brightness range of the scene is beyond the dynamic range of your camera (you can check this by referring to your histogram) bracket your exposures, you can choose the best image later or combine images into an HDR shot.
• Manual mode: Manual mode gives you complete control over the aperture, shutter speed and ISO to control exposure. A built-in light meter or an external light meter is needed to meter the subject and lighting and then you set the ISO, aperture and shutter speed

Below is a before and after image, this is image was shot in manual mode and under exposed to retain detail in the brightest parts of the scene, it was saved as a RAW file for post processing.

Finding the optimum exposure for your subject requires balancing technical considerations and creative intent to arrive at an exposure that best portrays your subject!