Metering is a setting we usually ignore when taking a picture even though it is very important.
It usually troubles the amateur photographers making them believe it has to do with the distance measuring.
This setting is not present in all the digital cameras but it is good to know that the metering feature of the camera measures the light amount reaching the sensor and helps with the exposure time of the subject.
The spot metering measures only a small portion of the frame, around 3-8% depending on the camera, represented only by a little circle in the viewfinder.
Through the qualities of this type of metering you can find out the accuracy of exposure measurement without the influence of another frame area and it is generally used for the frames where the light is behind the subject.
For example if the back of the subject is strongly illuminated –like a sunrise- and the front of the subject is underexposed, spot metering can measure correctly the light exposure reaching the subject’s face, calculating exposure so the subject will be captured clearly. The only thing worth mentioning is that the items around the subject will be still overexposed.
Another practical use of spot metering is the moment of photographing the moon because the very dark nature of the background will tend to overexpose the moon. The spot metering will expose the moon accurately and underexpose the rest of scene.
Center-weighted average metering concentrates the sensor between 60 and 80% of the sensibility in the center of the frame losing the sensibility for the sides. Some of the photo cameras allow the user to adjust the sensibility from the center to the sides.
This method has a great advantage because it does not allow the metering system to be “tricked” by the small light areas on the sides of the frame. Most of the times this type of metering brings up the best results in the photographed scenes.
The average metering calculates a media of the whole scene luminosity and sets an exposure without considering a certain area of the scene.
The partial metering is very similar to the spot metering the difference being the frame area used to measure the scene, because the partial metering covers 9-12 % of the scene. It can be used when you have areas with very strong light or on the contrary very dark areas.
The metering can help a photographer capture original frames and can turn the art of digital photography in a trip beyond the mere view of a subject into the light manipulation that can result an amazing photograph.