On a heavy overcast day with ISO 400, which aperture setting should be used to convert film speed to shutter speed?

On a heavily overcast day, the available light is significantly diminished, which requires careful adjustment of both camera settings to achieve a proper exposure. When using ISO 400 film, it is important to understand the relationship between aperture, shutter speed, and ISO.

The aperture setting controls the amount of light that enters the camera. A wider aperture (like f/2) allows more light to hit the film compared to a narrower aperture (like f/16). In overcast conditions, the light is soft and diffuse, necessitating a wider aperture to capture enough light for a properly exposed image.

Choosing an aperture setting of f/4 allows for a balance between light and depth of field, making it effective for capturing images in lower light without risking too much light loss, which is critical when the available light is already limited on a gray day. This setting would typically correspond to a moderate shutter speed, allowing you to maintain a proper exposure without requiring an excessively long or short shutter speed that could either lead to camera shake or underexposure.

While a setting like f/2 might seem favorable due to its ability to gather light, it could result in a very shallow depth of field, potentially affecting image sharpness and focus, especially in varying lighting conditions