What feature allows a digital camera to keep the shutter open for an extended period?

The Bulb setting is a specific function that allows a digital camera's shutter to remain open for as long as the shutter button is pressed. This feature is particularly useful for long exposure photography, such as capturing light trails, starry skies, or other low-light situations. When using the Bulb setting, the photographer can control exposure time beyond the limits of preset shutter speeds, allowing for creative effects and detailed nighttime images.

Other modes, such as Manual mode, provide control over various settings like aperture and shutter speed, but they do not inherently allow for unlimited exposure time without specific adjustments. Continuous shooting and Auto mode serve different purposes; continuous shooting captures a series of images in quick succession, while Auto mode automatically determines settings based on the scene. None of these alternatives facilitate the same extended exposure capability that the Bulb setting offers.