Exposure Meter

All light meters are calibrated to a standard measurement that reads middle gray. Which means, the range from black to white will be rendered as middle gray, and colors will be lightened or darkened depending on their color hue.

Reflective light meters read the intensity of light reflecting off the subject and incident light meters read the light falling on the subject. The reflective meter is aimed at the subject and the incident meter is aimed at the camera.

Cameras with built-in light meters are reflective. The light meter reads the exposure value of the scene and converts it to shutter speed and aperture settings based on the ISO.

Types Of Metering Modes
Matrix, Averaged, or Evaluated

This type of metering measures the light intensity of many different zones within the entire view finder and averages those results to create the aperture and shutter combination for the best exposure. Matrix metering is used for scenes that need to be photographed quickly and the subject has a mid-to-long dynamic range.

Matrix/Evaluated
Responsive image
1/2000 ƒ/7.1
Center-weighted
Responsive image
1/1000 ƒ/7.1
Center Weighted

Center weighted metering uses a circular area of about 50 to 60 percent in the center of the view finder and feathers out to the edges. Useful for portraits and offers reliable results when the subject is in the center of the scene.

Spot

The spot meter is a very small area within the viewfinder that lets you determine the dynamic range of the scene by reading the shadow and highlight values separately.

Spot
Responsive image
1/320 ƒ/7.1
Spot
Responsive image
1/800 ƒ/7.1
Spot
Responsive image
1/4000 ƒ/7.1