Lens luminosity refers to the ability of the lens to transmit light to the image sensor. The f/4.0 value is a specific aperture number that indicates the ratio between the focal length of the lens and the diameter of the entrance hole through which the light passes. The lower the number, the more light the lens lets through, and vice versa. In this case, it is a fixed, immutable value, which means that the size of the aperture cannot be changed on the camera. A lens with an aperture of f/4.0 is suitable for filming and shooting in good lighting conditions, for example during the day. In twilight or darker scenes, the camera must compensate for the lack of light by other means, such as increasing the sensor sensitivity or "ISO", which can lead to higher image noise. The aperture number also affects the depth of field, the range of distances over which objects in the image appear sharp. A value of f/4.0 helps to keep more of the scene sharp, which is often desirable for aerial shots of landscapes.
