Using manual mode isn’t all guesswork—a light meter built into the camera helps guide those decisions, indicating if the camera thinks the image is over or under exposed. Metering is actually based on a middle gray, so having lighter or darker objects in the image can throw the metering off a little bit. Metering modes indicate how the meter is reading the light. Matrix metering means the camera is reading the light from the entire scene. Center-weighted metering considers only what’s at the center of the frame and spot metering measures the light based on where your focus point is.