1 / 24

Understanding Optical Telescopes: Refractors vs. Reflectors

Explore the fundamentals of optical telescopes, including the two main types: refractors and reflectors. Refractors utilize lenses to focus light, offering steady images but facing issues like chromatic aberration and sagging lenses. In contrast, reflectors use curved mirrors to gather light, overcoming chromatic aberration, and are often lighter and more cost-effective, despite needing frequent alignment. This overview also delves into telescope magnification, brightness, historical advancements, and offers guidance on selecting the right telescope for your needs.

rowena
Download Presentation

Understanding Optical Telescopes: Refractors vs. Reflectors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Unit 3 Telescopes

  2. Optical Telescopes • Two basic types • Refractors • Reflectors

  3. Refractors • Uses lenses to gather and concentrate light

  4. Refractors • Advantages: • Refractor telescopes are rugged • Lenses inside the tube is sealed so it rarely needs cleaning • images are steadier and sharper • Disadvantages: • chromatic aberration • Lens supported only at the ends, lens will sag • Expensive, heavy

  5. Refractor

  6. Reflectors • Uses a curved mirror to focus incoming light

  7. Reflectors • Advantages: • Do not suffer from chromatic aberration • Can be made very BIG! • Less expensive, lighter • Disadvantages: • Optics need more frequent alignment • Open to the outside, need frequent cleaning • Secondary mirror can produce diffraction effects

  8. Reflector

  9. Types of Reflectors • Gregorian • Newtonian • Cassegrain

  10. Schmidt-Cassegrain

  11. Telescope magnification Magnification = focal length of telescope / focal length eyepiece e.g. focal length of telescope = 1000 mm focal length of eyepiece = 30 mm magnification = 1000 mm/ 30 mm = 33

  12. Brightness • The observed brightness of an object is directly proportional to the area of the telescope mirror, e.g. a 5 meter telescope will have a light gathering capacity 25 times (52) greater than a 1 meter telescope

  13. History of Large Telescopes • William Herschel (late 1700s)

  14. Mt. Wilson (1917) • 100 inch

  15. Hale (1948) • 200 inch

  16. Space Telescopes • outside the distortion of Earth's atmosphere • extremely sharp images • almost no background light

  17. Space Telescopes • Hubble • Spitzer • Chandra

  18. Kepler Space Telescope • Designed to discover Earth-like planets

  19. Herschel Space Observatory Launched in 2009 by the European Space Agency Sensitive to Infrared radiation

  20. Image Acquisition & Processing • Charge-coupled devices (CCDs)  computer (very efficient)

  21. Radio Astronomy

  22. How to pick a telescope • Start by using your bare eyes • Next, move up to binoculars • When you’re ready for a telescope, read/ research

  23. Choosing the right telescope • Performance • Purpose • Portability • Light Pollution • Price

  24. All other things being equal, the greater the mirror/ lens diameter the greater the light gathering ability • Primary Mirror Size        Square Inches of Aperture                       4"      12                        6        28                        8        50                      10        78                      12      113 • http://www.astronomics.com/main/category.asp/catalog_name/Astronomics/category_name/How%20to%20pick%20a%20telescope/Page/1

More Related