Irradiation distance and depth: the illumination distance of most shadowless lamps is 70-140cm or 60-130cm. That is, the shadowless light works best in this distance.
Illumination and color temperature: Illuminance and color temperature are actually an approximate concept. Both are to describe the intensity of the illumination of the shadowless lamp. Usually we think that the most ideal shadowless light is that light is similar to sunlight,around 4400-4600K.