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Homework Help: Galilean Teliscope

  1. May 18, 2012 #1
    I need to diagram a galilean teliscope for a project at school using a ray diagram. I know how to do the ray diagram for the first convex lens, but how does it work with the second concave lens. It always makes the image smaller for me. Does anyone know how to do this? Pictures would be great!
  2. jcsd
  3. May 18, 2012 #2


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    The image from the first (objective) lens is always closer to the eyepiece (secondary lens) than its focal length. Drawing the ray diagram that way should show that it enlarges.
  4. May 18, 2012 #3
    That works when you use two convex (converging) lenses, but I am using a convex lens for the objective and concave (diverging) for the eyepiece.
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