The T-setting, or Time setting, is a feature found on some older cameras that allows the shutter to remain open when the shutter release is pressed. The shutter stays open until the release is pressed a second time, giving the photographer full control over long exposures.
Photographers use the T-setting for night photography, light painting, or any situation requiring precise control over exposure duration. Mastering this feature allows for creative long-exposure effects while ensuring the photographer can manually control when the shutter closes for optimal results.