Final answer:
When shooting film, it is essential to keep the viewfinder covered to prevent light leaks that could overexpose the film. Light is a form of radiation that affects the exposure of the film, and careful control of light exposure is important for capturing desired images.
Step-by-step explanation:
When shooting film, you must always have the viewfinder covered by your eye or another object when rolling. This is important because film is sensitive to radiation, which in this context means light.
The more radiation the film is subjected to, the more exposed it becomes.
Therefore, if the viewfinder is left uncovered, light may leak in through the viewfinder and cause unintentional exposure, which can affect the final image.
It's crucial to be mindful of this to ensure the proper exposure and avoid damaging the film with unwanted light.