And that distance and knowing that amount of light is important because it's a little like you or I sitting around a campfire: You want to be close enough to the campfire so that you're warm, but not so close that you're too toasty and you get burned.
对距离与光照强弱的了解是非常关键的， 这就好像我们坐在一个篝火边上。 你会想要靠的够近好让自己取暖， 但是又不可以太近， 导致温度太高把自己烫伤。