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Ever wonder why you can get different exposures on the exact same scene with your Nikon camera using 3D Matrix Metering? The meter and AF system are linked in a way that usually produces great results. But for landscape photographers, it can sometimes cause overexposure if you focus on dark parts of the scene, like a shady foreground.
Nikon’s 3D matrix metering is an advanced exposure system that evaluates the entire color image. The same scene can be exposed differently, depending on the location of the active AF point. When the AF point falls on a dark part of the scene, the meter tends to open up the exposure (brighten it). If the AF point is on a bright part of the scene, the camera will expose the scene slightly darker. This difference in exposure can be particularly important to landscape photographers, who usually choose a foreground object for the focus point. If the foreground is relatively dark, the camera will often blow out the sky.
The solution is to first focus on the dark object in the foreground, and then lock focus (I use the AF-On button technique for this). Next, move the active AF point to a bright part of the scene. This allows the meter to bias the exposure to preserve highlight details in the final image.