A handheld meter can do something your camera’s meter usually cannot: measure incident light. Your camera’s built-in meter is a reflected meter, meaning it reads light bouncing off the subject. That means subject tone can mislead it—a white dress or dark clothing can push exposure away from what you intended.

An incident meter is placed at the subject and aimed toward the camera, so it measures the light falling on the subject regardless of color or reflectivity. That makes it especially useful in controlled situations like studio portraiture, product work, or balancing multiple light sources and flash.

It’s also useful as a learning tool because it helps you connect actual light levels to exposure settings more deliberately, instead of relying on automation.

For general outdoor shooting, though, a separate meter is often less necessary. Your camera’s reflected meter is already very capable, and bracketing can be a practical alternative when conditions change quickly. So the main reasons to buy one are: learning exposure/light more deeply, using incident metering, and working with studio or flash lighting.