From: dkcombs@panix.com   
      
   In article ,   
   Chuck Olson  wrote:   
   >   
      
      
   >       To be used as a magnifier,   
   >this lens would have to be held away from the face 10 inches or more,   
      
   Very interesting.  Please say some more (tutorial even) on that point,   
   what effect from the distance the lens is from the eye.   
      
   (Also, how far away for it to turn the perceived image upside-down?)   
      
      
   >and   
   >the text being magnified would have to be 10 inches or less beyond the lens.   
      
      
   Yes, "10 inches or more" vs "10 inches or less".   
      
   THANKS!   
      
      
   >Worn as  reading glasses, the +400 lenses would bring the user's focus from   
   >40 inches (longer than an arm's length) down to 8 inches (for reading very   
   >small print).  The focal distance of the lens can be determined by casting   
   >an image of a far distant scene on a sheet of paper and measuring the   
   >distance between the lens and the paper when the image is sharpest.   
   >   
      
      
   David   
      
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