Telescopes

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Telescopes

• Elizabeth Warner
• UM Observatory
• Dept. of Astronomy

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3 Basic Types

• Refractor
• Reflector
• Catadioptric

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Refractors

• Use lenses
• first telescopes

chromatic aberration spherical aberration
achromatic apochromatic
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Reflectors
spherical aberration collimation

• Use mirrors

newtonian
cassegrain
dobsonian
Herschelian
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Catadioptric
spherical aberration collimation
Schmidt-cassegrain Maksutov-cassegrain
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Properties
Light gathering power area (aperture) pr2 Reso
lving power 252,000 (observation wavelength)
/ (objective diameter). Magnification focal
length of scope/focal length of eyepiece
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I. Telescopes A. Refractor B. Reflector C. Cata
dioptric II. Mounts A. Alt-Az B. Equatorial C.
Dobsonian
Telescope Cheat Sheet
1/o 1/i 1/f lim o --gt ? magnification
fscope/feyepiece F/ratio f / a
a
f
focal length f aperature a
a
Light gathering power Resolving power (resolution)
lens objective concave convex chromatic
abberation achromat apochromat mirror primary sec
ondary spherical paraboloidal collimation
f
secondary
a
primary
f
a
f
eyepiece Barlow lens filters
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Mounts

• Alt azimuth
• dobsonian
• Equatorial
• German equatorial
• fork