Which component functions to control the amount of light striking the emulsion of film positioned in the focal plane?

Which component functions to control the amount of light striking the emulsion of film positioned in the focal plane?

• A. Shutter
• B. Diaphragm
• C. Filter
• D. Viewfinder

Answer: (B)

The diaphragm is the component that controls how much light reaches the film. It’s an adjustable opening inside the lens that can be made wider or narrower. A wider opening lets in more light, brightening the image (and reducing depth of field), while a narrower opening lets in less light, darkening the image (and increasing depth of field). The shutter determines how long that light is allowed to hit the film, not the amount at any instant, while a filter mainly changes the light’s color or quality, and the viewfinder doesn’t affect exposure.

The diaphragm is the component that controls how much light reaches the film. It’s an adjustable opening inside the lens that can be made wider or narrower. A wider opening lets in more light, brightening the image (and reducing depth of field), while a narrower opening lets in less light, darkening the image (and increasing depth of field). The shutter determines how long that light is allowed to hit the film, not the amount at any instant, while a filter mainly changes the light’s color or quality, and the viewfinder doesn’t affect exposure.