What is an F-stop? (A) Measurement of the flow of electricity (B) The size of the opening of a diaphragm (C) Measurement of the light temperature (D) The valve that stops the movement of a Camera mounted on a tripod Correct Ans: (B) Explanation: An F-stop determines the size of the diaphragm opening in a camera lens, regulating the amount of light entering the camera. It plays a crucial role in exposure, depth of field, and sharpness. Understanding F-stop settings helps photographers and cinematographers achieve creative control over their images. A lower F-stop number (e.g., f/1.8) means a wider aperture, allowing more light into the camera sensor. This setting is ideal for low-light photography and portraits, as it creates a shallow depth of field, blurring the background while keeping the subject sharp. In contrast, a higher F-stop (e.g., f/16) results in a narrower aperture, reducing light intake. This setting increases the depth of field, ensuring that both the foreground and background remain in focus, making it useful for landscapes or group shots. The other options do not describe an F-stop. Electricity flow is measured in volts or amps, not in it. Light temperature, measured in Kelvin, determines color tone. A camera valve on a tripod only controls movement, not aperture size. Mastering F-stops enhances creative composition, exposure control, and image sharpness, helping photographers and filmmakers achieve their artistic vision.