Spot metering will determine the exposure based on a very small circle around your focus point. This is good when you're focusing on a face. It's not so good when you focus on a white spot on a mostly black dog, as it will think the scene is brighter than it is. It's also not good when focusing on a black detail of a more bright scene, as it think the scene is darker than expected.


Other metering modes use a larger amount of the scene. This is great when there is no single specific element to expose correctly. It will attempt to properly expose the entire scene. If you used this mode, and metered on a person while there is a really strong backlight, you may end up with a darksilhouette, as the meter will be attempting to properly expose the bright background.You can attempt to compensate for that by metering on the ground, locking that exposure, then taking the photo. If the person covered the entire metering area, it would expose the person correctly. Because you don't want to meter the bright backlight, you could switch to spot metering to reduce the area the meter is looking at. Hopefully the person will cover the entire spot, giving them correct exposure. If you're still having trouble getting the auto exposure to be correct, you can use the exposure compensation or the fully manual mode to override the camera's choice.