Digital PhotographyLesson 4

Lesson Goals

Understand what exposure is.

Understand which camera settings affect exposure.

Be able to describe shutter speed, aperture, white balance and ISO settings.

Exposure

The amount of light reaching your camera's sensor is known as the exposure; this is controlled by two items on a camera - the aperture and shutter speed.

The aperture is a variable opening in front of the lens that adjusts to let more or less light through and the shutter speed is a cover over the sensor that controls the length of time that the light reaches it.

Settings

Shutter speed

Aperture

White balance

ISO

Aperture

Aperture refers to the opening inside a camera lens that controls the amount of light that falls onto the image sensor.

A large(wide) aperture allows more light(narrow) in and a small aperture allows less.

A narrow aperture will have the foreground in focus and the background blurred while the wide aperture will have more of the background in focus. This is known as depth of field.

White balance

White balance is the process of removing unrealistic colour casts, so that objects which appear white in person are rendered white in your photo.

Proper camera white balance has to take into account the "colour temperature" of a light source, which refers to the relative warmth or coolness of white light.

ISO

ISO affects the shutter speed/aperture combinations you can use to obtain correct exposure

ISO measures the sensitivity of the image sensor

Higher ISO settings are generally used in darker situations to get faster shutter speeds (for example an indoor sports event when you want to freeze the action in lower light)

If there is not enough light you can increase the ISO setting this can be done automatically or manually