In photography, the term "stop down" refers to the process of decreasing the size of the camera's aperture. The two words that make up this phrase are pronounced with the same stress: /ˈstɑp daʊn/. The first syllable, "stop," is pronounced with a long "o" sound, as in "boat." The second word, "down," is pronounced with the diphthong /aʊ/, which sounds like "ow" in "cow." Together, "stop down" is pronounced with two syllables of equal emphasis and a clear, distinct /d/ sound at the end.
Stop down is a phrasal verb that is predominantly used in photography and refers to the act of decreasing the aperture of a camera lens to reduce the amount of light entering it. This is done by adjusting the aperture to a higher f-number, such as F11 or F16, resulting in a smaller opening through which the light can pass. By "stopping down," the photographer can control the depth of field, which affects how much of the image is in focus.
The term "stop down" originates from traditional film cameras, where changing the aperture required physically stopping down the lens diaphragm. In modern digital cameras, however, the adjustment is often done electronically. Stopping down can have several effects on a photograph, such as increasing sharpness throughout the image, bringing distant objects into focus, and reducing the amount of light reaching the image sensor or film.
Additionally, stopping down can be used creatively to manipulate the aesthetic qualities of a photograph. By decreasing the aperture and increasing the depth of field, a photographer can create a sharper, more detailed image with greater clarity and fewer distractions. Furthermore, stopping down can be beneficial in situations where there is excessive brightness or when trying to capture scenes with a high level of detail.
The phrase "stop down" originates from photography and refers to the act of reducing the aperture size of a camera lens to allow less light to reach the film or image sensor, resulting in a shallower depth of field.
The term "stop" in photography comes from the early days of large format cameras, where it referred to a standardized measurement of the aperture size. Each increment of a full stop would halve the amount of light entering the camera. The term "down" is used to indicate reducing or narrowing the aperture size.
Therefore, "stop down" in photography signifies the act of closing the aperture to a smaller size, reducing the amount of light allowed into the lens. It has since been adopted into common usage in the photography community.