Final answer:
Most light meters are designed to average out a subject to match middle gray, which reflects 18% of the light that falls on it. This ensures accurate exposure settings for capturing the overall brightness and contrast of the scene.
Step-by-step explanation:
Most light meters are designed to average out a subject to match middle gray, which reflects 18% of the light that falls on it.
To understand this, we need to consider that light meters measure the amount of light falling on a subject and calculate the exposure settings based on that. Middle gray is a standard reference point for exposure measurement because it reflects an average amount of light. By averaging out the subject to match middle gray, the light meter ensures that the exposure settings accurately capture the overall brightness and contrast of the scene.
For example, if a subject reflects more light than middle gray, the light meter would compensate by reducing the exposure to prevent overexposure. On the other hand, if a subject reflects less light than middle gray, the light meter would increase the exposure to prevent underexposure.