1 m9 J' N0 L, Z+ c: q/ z/ F
: q8 D! S( |; D* l0 k1 H. I- z+ o4 c, U; V
A graduated neutral density filter, also known as a graduated ND filter, split neutral density filter, or just a graduated filter, is an optical filter that has a variable light transmission. 简单的说渐变滤镜