On Tuesday, November 23, 2010 4:11:40 PM UTC-8, Optical wrote:   
   > I was having this argument at work.   
   >    
   > Some claim that reading glasses work because they magnify small print.    
   > They claim that reading glasses sold at drug stores are labelled in   
   > terms of their "magnification power" or strength.   
   >    
   > I was arguing that the goal of reading glasses is not to magnify, but to   
   > move the focal point, and that they don't really perform any   
   > magnification.   
   >    
   > Who's right?   
   >    
   > Do many people use the term "magnification" incorrectly when talking   
   > about reading glasses?   
      
   I just picked up a page and put on my bifocals, that function as my reading   
   glasses, allowing objects to be focused on at closer distances than would   
   otherwise be possible. If I hold the page so that it is in focus with my   
   glasses on (looking through the    
   part at the bottom designed for close work) and then raise the glasses with my   
   other hand, keeping the paper in the same position, the print becomes fuzzy,   
   and very very slightly smaller. My point is that while no one can tell someone   
   else precisely what    
   he sees, that based on my experience that I disagree with your observation as   
   to what takes place.    
      
   The tops of my lenses are designed to compensate for my being myopic and so   
   they are ground to negative diopters, and when I do the same test, looking at   
   something in the distance, it appears smaller and in sharp focus compared to   
   looking at it without    
   my glasses. When I use a rifle scope, I can compensate for this loss of   
   magnification by mounting a positive diopter lens on the scopes eyepiece, and   
   refocusing it to the resultant shorter focal length by screwing it to a point   
   of less extension (forward    
   of its previous position) on the scope. There is some loss of eye relief, but   
   not so much that it is a problem.   
      
   --- SoupGate-Win32 v1.05   
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