What's the difference between the camera's UV CPL ND series?

Ultraviolet filter: produced in the film age, its main function was to prevent ultraviolet rays from entering. In the digital age, there is only one function, which is to protect the lens.

CPL filter: Chinese name is polarizer, and its principle is to filter out part of the reflection of the picture by polarized light, which has a good effect of eliminating reflection for shooting water, mirror and sky.

ND filter: the Chinese scientific name is the reducing mirror, which, as the name implies, reduces the luminous flux of the camera and is used in the fields of slow door, macro and flash photography.

Add another one: GND filter: Chinese scientific name neutral gray gradient filter, which is equivalent to reducing half the light without reducing half the light. It is used in some cases where the light contrast between the sky and the ground is too large.