They can dance in one place and have billions of manifestation bodies at the same time . this is because their minds are never defocused; they have reached the state of never lacking concentration . the sun shines on every corner of the earth without having to consume anything; however, a candle can only illuminate one spot and yet its radiance is short-lived 比方说，他可以一边跳舞一边千百亿化身这样子，因为他的心永久不分散，他已经得到不分散的程度，像太阳照耀天下四方，它不会消耗什么不过蜡烛只能照一个地方而已，而且照一会儿就不能照了。
(2 ) focus measure based on wavelet analysis is introduced to differentiate those images taken slightly defocused; ( 3 ) a simple and functional optical imaging model is presented . on the basis of the model the necessity to select focus windows is expatiated, and the limits of the traditional methods are shown (3)提出了一个简单实用的光学成像模型，在此基础上分析了对焦窗口选择的必要性，指出了传统方法只对特定成像目标才能取得较好的效果，然后对不同成像目标的对焦窗口选择策略进行了探讨。
