Here is an example: left side of below picture shows an optical focus system. 

Consider it as a Microscope, Industrial Camera is put at the image location(yellow arrow). For some reason, the user wants to zoom out or zoom in by tuning Microscope lens. Focal point of the lens will be changed. Top right corner of below picture shows the consequence. The image now moves to the location of the green arrow. Due to the factor the industrial camera and Microscope are physically fixed with each other, the camera can only stay at the original yellow image location. To get it focused again, object distance should be changed by lowing or highing the microscope.

Now consider it as a Telescope or Spotting Scope to watch bird. For some reason, the bird jumps from one tree branch to another tree branch which is further away. Bottom right corner of the picture shows the consequence. The image now moves to the location of blond arrow. To get it focused again, the user needs to manually move the camera closer to Telescope or move the telescope colser to the bird. 

It could be nice if we can automatically move the camera to the right location to catch the focused image on above examples. However, the camera is too heavy to be accurately and quickly driven to the focuses location by motors.  What if we do not move the camera but move the sensor inside the camra? Yes, that is the solution! The sensor moving techlogy is patented by us.