In photography, the amount of light to which film is exposed is influenced by:

In photography, the amount of light to which film is exposed is primarily influenced by the aperture and shutter speed. The aperture is the opening in the lens that allows light to pass through; it can be adjusted to let in more or less light, affecting the exposure. A wider aperture allows more light to hit the film, while a narrower aperture lets in less light.

Shutter speed refers to the amount of time the camera’s shutter remains open to allow light to hit the film or sensor; a faster shutter speed means the film is exposed for a shorter amount of time, letting in less light, while a slower shutter speed allows more light to be captured over a longer period. Together, these two factors—aperture and shutter speed—are critical components of the exposure triangle in photography, balancing light and ensuring that images are neither overexposed nor underexposed.

Other factors, such as film type and lens length, do have an impact on the final image, but they primarily relate to the characteristics and quality of the image rather than directly influencing the exposure itself. Likewise, lighting conditions and ISO affect how the camera interprets available light and can assist in achieving desired exposure, but are not direct adjustments made to the exposure process. Camera angle