Digital cameras are getting surprisingly good at capturing proper exposure in most lighting conditions. Cameras judge proper exposure based on how much light is reflecting off of the scene back to the camera. This is called “Reflective Metering”. The camera compares the reflected light value against 18% gray (middle gray). This method works out fine when a majority of the metered area is a medium color however, is problematic when shooting bright or dark scenes.
For example, say you were to take a photo of a snow covered field in bright sunlight. If you meter your exposure off of the snow the image would turn out under-exposed and the snow would look gray instead of bright white. Why? because the camera is trying to map the bright white of the snow – which encompasses most of the image – to 18% gray.
There are a number of ways to combat this problem. Here are a few common ones:
- Use when in aperture priority, shutter priority, or auto modes use exposure compensation to override the camera’s meter.
- Switch to manual mode and purposefully under/over-expose until the scene is exposed properly.For tips on how to use manual mode check out our Manual Exposure Cheatsheet
Using a gray card like this one , or a light meter are also great ways to help take the guess work out of figuring out the proper exposure. Using the camera’s spot metering setting and metering off of a mid tone color in the scene works great also.