There are many types of magnification for sight lenses, such as 3-6 times sight lenses that can be used for regular shooting, 9-12 times sight lenses that are suitable for long-distance shooting, and higher magnification sight lenses that are suitable for long-range shooting. In the 4x32 number, the number 32 represents the effective optical diameter unit of the convex lens (objective lens group), which is in the millimeter level. The eyepiece refers to the lens closest to the eye, while the other end of the lens is the objective lens. At a certain magnification, a larger objective lens can pass through more light to obtain clearer images. As the multiplier increases, the required light also needs to increase. Otherwise, you will see a large shadow, and the most intuitive feeling is that the image will darken. That's why high magnification sights require larger objective lenses. The reason lies in this. A 4x32 sight is brighter than a 12x40 sight because the contribution of a 32mm objective to light intensity is greater than that of a 40mm objective.