What f-stop should be set when using 400 speed film with a shutter speed of 1/500th in deep shade?

When using 400 speed film with a shutter speed of 1/500th of a second in deep shade, selecting f/8 is the appropriate choice due to the need to let in a moderate amount of light while ensuring an adequate depth of field.

In deep shade, light levels are significantly lower than in direct sunlight, so a wider aperture (lower f-stop number) might allow too much light and lead to overexposure, especially with a faster shutter speed like 1/500th. Conversely, a smaller aperture (higher f-stop number) helps control the light exposure, preventing overexposure, while also maintaining suitable sharpness throughout the image by offering a deeper depth of field.

The f-stop of f/8 provides a balanced trade-off, capturing enough light for proper exposure under shaded conditions while also delivering sufficient focus across the subject, ideal for many typical photography scenarios encountered in those lighting conditions.