From: nospam@nowhere.org   
      
   This may sound like a strange question, but is it possible to add an external   
   aperture stop to a fixed lens to increase it's depth of field?  If so, how   
   would   
   you do it?   
      
   The reason for this question is I have a very old Imacon Precision II film   
   scanner.  I want to scan mounted slides with it, but when they made this   
   scanner, they used an 8W high CRI fluorescent tube and had to get a fast lens   
   because the light source was limited.  This resulted in a shallow depth of   
   field, and you can't get good edge-edge sharpness with a mounted slide (because   
   of the curvature of the film).   
      
   I can make a new light source using high CRI LEDs, and stop down the lens, but   
   I'm not sure how to do it so the lens sharpness isn't reduced.   
      
   Thanks in advance.   
      
   Steve   
      
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