field of view vs ken

field of view

noun
  • The angular extent of what can be seen, either with the eye or with an optical instrument or camera. 

ken

noun
  • Range of sight. 

  • Youth or children's group. 

  • A Japanese unit of length equal to six shakus 

  • Knowledge, perception, or sight. 

  • The tsurugi 

verb
  • To know, perceive or understand. 

How often have the words field of view and ken occurred in a corpus of books? (source: Google Ngram Viewer )