The letter "S" on a film camera typically refers to the Shutter Priority mode. Shutter Priority is a semi-automatic shooting mode that allows the photographer to control the camera's shutter speed while the camera chooses the appropriate aperture to maintain proper exposure.
In this mode, the photographer selects a desired shutter speed, and the camera automatically sets the aperture to achieve proper exposure. This mode is often used by photographers who want to control the amount of motion blur in their images, such as when photographing fast-moving objects or to freeze or intentionally blur motion for creative effect.
For example, if a photographer wants to freeze motion in a fast-paced scene, they might set their shutter speed to a fast value, such as 1/500th of a second. The camera will then choose the appropriate aperture to maintain proper exposure based on the available light and the ISO setting.
It's important to note that in Shutter Priority mode, the photographer is still responsible for keeping an eye on the exposure meter and adjusting the shutter speed as necessary to ensure proper exposure. If the chosen shutter speed results in an aperture that is too wide or too narrow for the available light, the exposure meter will indicate this, and the photographer must adjust the shutter speed accordingly.
In summary, the "S" on a film camera refers to Shutter Priority mode, a shooting mode that gives the photographer control over the camera's shutter speed while the camera chooses the appropriate aperture to maintain proper exposure. This mode is useful for photographers who want to control the amount of motion blur in their images and can be a helpful tool for achieving creative and well-exposed shots.
Source: "Understanding Shutter Priority Mode." Digital Photography School, 8 Feb. 2023, https://digital-photography-school.com/understanding-shutter-priority-mode/.