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REFRACTING TELESCOPE (AKA Refractor):   A refracting telescope uses lenses to bend and focus light.  Of the different types of telescopes, a refracting telescope operates most similarly to a human eye.  The objective lens in a “refractor” is like the lens of our eye.  It is convex, so it bends light to a point.  The distance at which the bent light comes into focus is called the focal length.  In our eyes, this point is on our retina.  In a refracting telescope, this is where the eyepiece catches the light and magnifies it.  This is the type of telescope that Galileo used. The biggest obstacle with this type of telescope is that it tends to get very heavy and very long as the diameter of the objective lens increases to let in more light.  George Hale is famous for building the largest refracting telescope in the world in 1890 and housing it at theYerkes Observatory in Wisconsin. 

Denver has its own giant refracting telescope at Observatory Park in the Chamberlin Observatory.  

Concave vs. Convex

 yerkes 40 in refractor

Inside the Chamberlin Observatory in Denver
Inside the Chamberlin Observatory in Denver
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