Your camera uses reflected light to create a photographic image. The whiter areas in your frame reflect more light than dark areas. Your camera relies more on the whiter areas to determine your exposure. Each metering mode will give you a slightly different creative look based on the light it reads.
Camera makers use different names for their metering methods. Essentially, they fall into three categories of evaluative, center weighted, and spot metering.
Evaluative metering uses the light from the entire frame to determine the correct exposure for a photo. Given a high contrast subject in your frame your camera is going to balance all the light to create an exposure.
Evaluative metering may also be called multi-segment, pattern, zone or overall metering.
When To Use Evaluative?
- When the light is even, without a lot of contrast in your frame.
- It’s often recommended that beginning photographers start here.
Notice how bright the image. You can see details throughout the frame. Whites are very bright. Notice that the shutter speed is a slow 1/100th of a second.
Center Weighted Metering
Center weighted metering works similarly to spot metering but evaluates the light from a larger area in around the center of your focal point.
When To Use Center Weighted?
- When you want your main subject exposed correctly and don’t care about the background exposure.
- When you want more accuracy than evaluative metering provides.
Notice how the background is darker in the image. Compare it to the previous. You can see fewer details in the frame now as many are lost in the shadows. Notice that the shutter speed has increased to 1/200th of a second, letting less light in.
Spot Metering determines the exposure based upon the light at your focal point. If your subject is dark against a blue sky, you will likely expose your subject correctly but “blow out” the sky making it white. Spot metering works well in high contrast situations. The key is looking at your subject and determining the spot you will meter.
Spot metering may also be called partial metering.
When To Use Spot Metering?
- In back lit situations, when you want the subject exposed correctly.
- When your subject is either much darker or much lighter than your background.
- In low light situations.
Notice how spot metering limits the light to the main subject. Very few of the details remain in the darker portions of the frame. The shutter speed has increased to 1/400th of a second, letting in even less light from throughout the frame.
In Program, Aperture Priority, Shutter Priority and Manual modes you can choose your metering mode. For the location of your specific buttons for changing your metering mode check in your manual under “metering” or “exposure.”
So which of the three metering modes is correct? While each one has situations that it works best in, ultimately the best mode is about the creative effect you are looking for.