The sunny day rule recommends which f-stop for most outdoor photography at 100 ISO?

The sunny day rule is a guideline for photographers that helps determine the correct exposure settings in bright outdoor sunlight, particularly for film or digital cameras set to an ISO of 100. According to this rule, f/16 is commonly suggested as the ideal aperture for sunny conditions.

This recommendation is based on the principle of the exposure triangle, where aperture plays a crucial role in controlling the amount of light hitting the camera sensor or film. By setting the aperture to f/16, the photographer allows a moderate amount of light to enter the lens, which is suitable for the bright conditions of a sunny day without overexposing the image.

Using f/16 at ISO 100 ensures the depth of field remains adequate, providing enough sharpness throughout the scene, which is often desirable for outdoor photography. This setting allows for good focus on subjects and ensures that images remain well-defined and vibrant in color under intense sunlight.

While other f-stop options might still work under different conditions or for various creative effects, f/16 at ISO 100 stands out as the recommended setting for achieving optimal exposure on bright days, thereby making it the correct choice.