The Bare Basics of a Digital Camera: Exposure

BARE BASICS:

The 3 most important modes of the camera are quite straight forwardly named:

A Mode: Aperture Priority. (good for changing Depth of Field and manually controlling Aperture)

S Mode (also known as T mode): Shutter Priority. (good for freezing or blurring motion and manually controlling shutter speed)

M Mode: Manual Exposure. (maximum control of exposure)

The mode button is located on the top of the camera, and can be changed according to which setting you require.

EXPOSURE:

Exposure: The act of exposing image sensor to light.

We control this by controlling the amount of light we let into the lens.

Aperture:

Aperture: is the space in the camera lens which the light passes through, when you adjust the aperture to gain focus, you adjust the amount of light you are allowing through the lens. Aperture controls the brightness of an image.

The Aperture is referred to as the f-stop, and (like the sizing of paper) the smaller the number, the bigger amount of lens is uncovered to allow light through.

SHUTTER SPEED:

Shutter Speed: is the measurement of time the shutter is open.

When capturing a moving object, the shutter speed will be fast to capture a precise image or slower for a more blurred effect.

If the shutter speed is increased by one step, the amount of time the shutter is open is reduced by half.

However, if the shutter speed is decreased by one step, the amount of time the shutter is open is increased by half.

The longer the shutter is open for the more light is is let in, adjusting exposure.

So basically:

Short shutter speed = less light coming in.

Long shutter speed = more light coming in.

DEPTH OF FIELD:

Depth of Field: is  the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image.

Depth of Field can be controlled using a number of variables such as shutter speed and aperture and IOS setting.

IOS:

IOS: is a measure of the camera's sensibility to light.

The darker the environment being photographed is, the higher the IOS setting needs to be.

On the other hand, the lighter the environment being photographed is, the lower the IOS setting needs to be.

When lighting is poor, flash can be used to light a subject but the drawback to this is flash units have a limited range. So if the IOS is raised the subject and background is able to be exposed well without the need for flash at all.

This diagram may help when trying to locate buttons on the camera (mine being a Nikon D7000) but all have similar layouts.

For any extra information on aperture, shutter speed and camera button functions refer to:

http://www.kenrockwell.com/nikon/d7000/users-guide/controls.htm

http://imaging.nikon.com/history/basics/