Does Zen have an unusual view of samadhi?
'Samadhi' generically means 'collectedness' or 'concentration'. 

The Pali states there are two types of concentration, namely, 'right' &amp; 'wrong': 


  In one of right concentration, wrong concentration is abolished...
  
  MN 117


'Right concentration' is defined as concentration that has seven supporting &amp; requisite factors:


  Any singleness of mind equipped with these seven factors — right view, right resolve, right speech, right action, right livelihood,
  right effort &amp; right mindfulness — is called noble right concentration
  with its supports &amp; requisite conditions.
  
  MN 117


Therefore, an expert marksmen trained to assassinate people in war has 'samadhi' but it is 'wrong samadhi' because it is not supported by the above seven factors. 

In fact, if a 'Zen samadhi' is not supported by the above seven factors, particularly 'right view', it is not 'right concentration' according to the Pali. 

As for the word 'jhana' or 'absorption', this generally refers to a 'meditative' concentration.