光源相对主体越大、越近，阴影边缘越柔和。把硬光打进柔光布或反射面，而不是单纯降低亮度；记录光源大小、距离和角度，换场景时才能复现。 A source becomes softer as it gets larger and closer relative to the subject. Bounce or diffuse a hard source instead of merely dimming it, and record size, distance, and angle for repeatability.