Traditional Culture Encyclopedia - Photography major - What does ND mean?

What does ND mean?

ND in the camera refers to the reducing mirror, which generally has specifications such as ND2, ND4 and ND8. The larger the value, the stronger the dimming effect. In photography, reducing the amount of light input means that the exposure time is longer and the depth of field is larger. Or chemical elements? Neodymium ... OK ... I haven't studied chemistry yet ... I suggest you go to Baidu Encyclopedia .../view/view/478123.htm.