还记得前面提到的闪光灯预闪吗？

Remember above how the flash sends out a pre-flash?

youdao

闪光灯会预闪并把曝光值记忆下来，注意你只有16秒的时间重新构图拍摄。

The speedlight will pre-flash that area and lock that exposure into memory. I might caution you that you have 16 seconds to then recompose and take the shot.

youdao

闪光灯输出功率的计算仍然是根据预闪反射光的中心加权测量结果。

The flash power calculation is also based on centre-weighted metering of the light reflected by the pre-flash.

youdao