TIP: Mastering exposure compensation

One of the coolest feature of a windows phone is the ability to change settings. You can change a whole host of features including:

• Scenes
• ISO
• Exposure value (EV)
• White Balance
• Aspect Ratio
• Focus Assist.

A setting you should get use to playing with is the exposure value (EV). This setting allows you to compensate for difficult exposure condition.

Exposure compensation allows you to fine tune your camera's metering system.

When you take a photo, the camera sets the shutter speed based on the aperture and metering system.

The metering system of a camera can be tricked under two types of conditions.

The first is in a scene with the majority of it being black. Good examples include a portraits where the subject wears black. The camera would over exposure this scene as the camera increases the exposure to make the scene neutral grey.

The second type of scene is with the majority of it is white. White wedding dresses often cause underexposure of the image as the camera tries to make it neutral grey.

Exposure compensation addresses this issue by forcing the camera to decrease or increase an exposure value (EV). +/-1 EV is one exposure stop (+/-). e.g. If EV0 (the default exposure calculated by the camera) is 1/20s, EV1 forces the exposure to be 1/10 (1-stop slower). On the opposite end EV-1 forces the exposure to be 1/40s (1-stop quicker).

On a recent trip to Jenolan caves, the default metering would result in overexposure. This is due to the white subject matter and the lights used to light a cave feature. To compensate, I set the exposure value to -2.0 EV, to compensate. The result is shown below.

EV0 the default camera exposure blows out all the detail in the minaret. EV of -2.0 preserves the detail and results in the correct exposure for the scene.