一、照相机的原理例1我们生活中使用的照相机是利用光学成像原理制成的,它的镜头相当于一个透镜,照相时景物到镜头的距离应该2倍焦距(选填“小于”、“大于”、“等于”).分析:普通的照相机,都是利用把物体放在凸透镜二倍焦距之外时,能在光屏上成倒立、放大、实像原理,如图1所 First, the principle of the camera Example 1 The camera used in our life is made using the principle of optical imaging, its lens is equivalent to a lens, the distance between the scene and the lens should be 2 times the focal length (optional “less than”, “greater than ”Equivalent to". Analysis: The general camera is to use the object placed outside the convex lens twice the focal length, can be inverted, enlarged, real image principle on the screen, as shown in Figure 1