From: g.gerardin@gmail.com   
      
   Hello,   
      
   My question is really basic but I know nothing about optics.   
   This image shows a lens focusing light at 2x its focal length, and I don't   
   understand why:   
   http://irpoyser.co.uk/sites/defaultsite/modules/user/MakingTeles   
   opes/images/img13.jpg   
      
   The image is from this page, at the 15.ii section "The simplest relay   
   system":   
   http://irpoyser.co.uk/index.php?page=109   
      
   The document states that in a basic relay system (single lens) with a   
   magnification of 1:1, u and v are/should be equal. I don't get that as   
   well. ANy intuition was that u should be related to the objective lens'   
   focal length, while v should be related to the relay lens' focal length.   
      
   Any help would be greatly appreciated.   
   Thanks   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)