Digital Camera Exposure

Most cameras have several exposure modes. As well as a fully automatic or programmed mode, they may have various other modes.

Scene Modes
Scene modes such as landscape, night, sports, portrait modes are still automatic, but give more suitable settings for these particular types of pictures. For example the sports mode will set higher shutter speeds to cope with moving subjects. If you want the camera to do as much as possible for you and there is mode for the kind of pictures you want to take, it makes sense to use it.

Control Modes
Control modes give you more control over the way the camera settings are made. They are more common on more expensive cameras. They include:

Aperture priority - allows you to set a particular aperture and the camera adjusts shutter speed to give correct exposure

Shutter priority - allows you to set a particular shutter speed and the camera will chose an aperture to give correct exposure

Manual Mode - on some cameras, allows you to set both aperture and shutter speed (and lets you get the exposure wrong!) but on others simply gives access to more camera settings that automatic mode.

Under and Over-Exposure
Underexposure means the sensor has not received enough light, and it makes the picture look too dark overall. Often parts of the image which should have detail will be completely black.

Overexposure means too much light has reached the sensor, and the picture will look too light, usually with some parts completely white.

With small amounts of underexposure you can probably correct the image by using image manipulation software - such as Photoshop Elements. Overexposed images have often completely lost detail in the highlights that cannot be restored.

One advantage of using raw files is that they usually allow more correction of exposure in software, although it is still easy to lose all highlight detail.

Exposure Compensation
This is a vital feature that enables you to adjust the auto-exposure the camera is giving. If your pictures are too light, you need to decrease exposure, and if they are too dark, to increase exposure. Check in the manual how you can use exposure compensation. On some cameras it is one of the things that only 'manual' mode will allow,

Histogram
This is a display that helps advanced users to check exposure, by displaying a bar chart of light showing the light intensities. A properly exposed image should have a chart that goes to zero before either end. It's also generally best to get the curve falling to zero close to the right end of the chart.