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Text File  |  1993-01-08  |  917 b   |  26 lines
  1. Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU
  2. Path: sparky!uunet!paladin.american.edu!auvm!CFA.HARVARD.EDU!GEARY
  3. Return-Path: <geary%cfa3.DECNET@cfa.harvard.edu>
  4. Message-ID: <9301081501.AA29496@cfa.harvard.edu>
  5. Newsgroups: bit.listserv.scuba-l
  6. Date:         Fri, 8 Jan 1993 10:01:51 -0500
  7. Sender:       Scuba diving discussion list <SCUBA-L@BROWNVM.BITNET>
  8. From:         geary%cfa3.DECNET@CFA.HARVARD.EDU
  9. Subject:      Lenses and diopters
  10. Lines: 14
  11.  
  12. Referring to Bob Claeson's post on mask lenses, I think you have your
  13. signs wrong, Bob.
  14.  
  15. Nearsighted (myopic) people need negative lenses (- diopters, thinnest
  16. at the center) to achieve focus. Farsighted ones need positive
  17. lenses (+ diopters, thickest at the center).
  18.  
  19.  
  20.              OOo O                John C. Geary
  21.              O oO                 PADI DM-52283
  22.               o                   geary@cfa.harvard.edu
  23.        _____ o o
  24.       (_/-\_)..
  25.      ===(O).
  26.