What should be used to convert file speed to shutter speed on an overcast day?

On an overcast day, the available light is significantly reduced compared to a sunny day, which means that a photographer needs to use a wider aperture to allow more light into the camera. The concept of using different f-stops relates to the exposure triangle (shutter speed, aperture, ISO) where aperture plays a critical role in determining how much light you let in.

Using f/5.6 strikes a balance between allowing sufficient light for adequate exposure and maintaining control over depth of field. It is a moderate aperture that is capable of compensating for the lower light conditions typically present on cloudy days. A wider aperture (like f/2.8) would allow even more light but might not be necessary depending on other settings like ISO or shutter speed. Using a smaller aperture (like f/8.0 or f/11.0) would likely result in underexposure, as they limit the amount of light hitting the sensor, which is not ideal when light is already compromised on an overcast day. Therefore, f/5.6 effectively converts file speed to shutter speed while ensuring proper exposure in these conditions.