Sunday, April 26, 2015
YOLO COUNTY NEWS
99 CENTS

Explorit: Learn about telescopes and accessories

By
From page A3 | November 23, 2012 |

By Vinita Domier

Join us Saturday evening, Dec. 8, at 7 p.m., when we will discuss the different types of telescopes and accessories. For those interested in examining telescopes with thoughts of purchasing one for the holidays, we will have a variety of telescopes and binoculars set up for display at Explorit beginning at 6 p.m. We also will look at the stars in the night sky following the main program, weather permitting.

On a clear night far from city lights, we can see about 2,000 to 3,000 stars with our naked eyes. To see millions of stars, we need to use telescopes or binoculars. Telescopes work like our eyes. The image formed is upside-down and flipped right to left. The brain corrects the eyes’ image to its right orientation. In a telescope, the image’s orientation is usually not corrected.

There are three basic types of telescopes. Refracting (lens) telescopes use lenses to refract or bend light to produce an image. The primary convex objective lens (at the top of the telescope) collects and focuses light on the smaller eyepiece lens (at the base). It has excellent contrast but gets expensive and bulky with large diameter lenses.

Reflecting (Newtonian) telescopes use mirrors to reflect light to produce an image. Light is collected by a concave primary mirror (at the base of the telescope) and reflected back to a flat secondary mirror (near the top of the scope), and then reflected on the eyepiece lens. It has medium contrast, is relatively inexpensive, but bulky as size increases.

Combo (Schmidt-Cassegrain or Maksutov-Cassegrain) telescopes “fold” light by using a combination of mirrors and lenses to form an image. Light is collected by a concave primary mirror (at the base of the telescope) and reflected back to a flat secondary mirror and correcting lens (at the top of the scope), and then reflected on the eyepiece lens. It has a condensed, portable tube and is less expensive than a big refractor.

Eyepiece lenses focus the collected light to the eye, and determine the magnification, brightness and contrast of the image. Eyepieces contain two to five lens elements with single or multiple anti-reflective coatings. The quality of an eyepiece is determined by its make, focal length, apparent field of view (width of the field of view) and eye relief (distance between eye and eyepiece lens).

Telescopes:

* Collect light coming from a star, thus making it appear brighter — light-gathering power (proportional to the square of the diameter of the objective lens/primary mirror);

* Bring out details — resolving power (equal to the wavelength of light divided by the diameter of the objective/primary lens or mirror); and

* Enlarge a section of the sky — magnifying power (equal to the focal length of the eyepiece divided by the focal length of the objective/primary lens or mirror). The actual field of view is equal to the apparent field of view of the eyepiece divided by the telescope’s magnification.

————

Explorit’s “Beyond the Table” exhibition will be open from 1 to 5 p.m. on Dec. 22-23, Dec. 26-31 and Jan. 2-6. We hope you will join us for some science fun and discovery over the holiday break. Explorit is at 3141 Fifth St. in Mace Ranch. For more information, call 530-756-0191 or visit www.explorit.org.

Comments

comments

Special to The Enterprise

  • Recent Posts

  • Enter your email address to subscribe to this newspaper and receive notifications of new articles by email.

  • .

    News

    Davis team wins world robotics championship

    By Anne Ternus-Bellamy | From Page: A1 | Gallery

     
     
     
    Nepal quake death toll exceeds 1,800

    By The Associated Press | From Page: A2 | Gallery

    Spring storm delivers late rain, snow to Northern California

    By The Associated Press | From Page: A2

     
    At the Pond: Plenty of pleasures in our bioregion

    By Jean Jackman | From Page: A3 | Gallery

    Pioneering organic chef presents her memoir Monday

    By Special to The Enterprise | From Page: A4

     
    Suspect in UCD assault arrested

    By Lauren Keene | From Page: A4

    Dog park marks anniversary with cleanup

    By Special to The Enterprise | From Page: A4

     
    Rail-safety bill passes Senate committee

    By Special to The Enterprise | From Page: A4

    Free Family Bike Clinic set Sunday

    By Enterprise staff | From Page: A4

     
    Watch them in action

    By Julia Ann Easley | From Page: A5

    Stocks rise on tech earnings; Nasdaq adds to record

    By The Associated Press | From Page: A8

     
    Dodd speaks as part of public policy series

    By Special to The Enterprise | From Page: A9

    We did it (together)!

    By Enterprise staff | From Page: A10

     
    $2.72 million judgment ordered against Dollar Tree Stores

    By Special to The Enterprise | From Page: A10

    Fly Fishers to hear about advanced streamer tactics on Tuesday

    By Special to The Enterprise | From Page: A11 | Gallery

     
    Bicycle activist will speak Monday at Hall of Fame

    By Enterprise staff | From Page: A11 | Gallery

    UCD hosts bike auction Saturday, May 2

    By Enterprise staff | From Page: A11 | Gallery

     
    .

    Forum

    Those texts still linger

    By Creators Syndicate | From Page: B6

     
    New ways of giving locally and beyond

    By Marion Franck | From Page: B6

     
    Study questions accuracy of tumor gene mapping

    By The Associated Press | From Page: B6

    Water, water everywhere?

    By Letters to the Editor | From Page: A12

     
    Mayor’s Corner: A spirit of renewal permeates Davis

    By Special to The Enterprise | From Page: A12

    More work to do for a safe Picnic Day

    By Our View | From Page: A12

     
    Tom Meyer cartoon

    By Debbie Davis | From Page: A12

    Poker proceeds help youths

    By Letters to the Editor | From Page: A12

     
    Invest in water of the future

    By Letters to the Editor | From Page: A12

     
    Anaheim, where The Force is with you

    By Sebastian Onate | From Page: A13 | Gallery

    .

    Sports

    Davis gets two baseball wins in two days

    By Spencer Ault | From Page: B1

     
    Grizzlies dominate young Blue Devils on Senior Night

    By Thomas Oide | From Page: B1 | Gallery

    Energy, fan-friendly happenings highlight UCD spring football game

    By Bruce Gallaudet | From Page: B1 | Gallery

     
    Blue Devil golfers capture CAL Invitational title

    By Enterprise staff | From Page: B1

    UCD roundup: Aggies reach water polo semifinals

    By Enterprise staff | From Page: B2

     
    Blue Devil swimmers are up to the challenge

    By Enterprise staff | From Page: B2 | Gallery

    Babich brings the heat as DHS girls stick it to Oak Ridge

    By Enterprise staff | From Page: B12 | Gallery

     
    DHS softball struggles continue against Sheldon

    By Enterprise staff | From Page: B12 | Gallery

    .

    Features

    .

    Arts

    History comes alive in ‘The Sacramento Picture’

    By Derrick Bang | From Page: A1 | Gallery

     
    .

    Business

    Big Italian food, sports bar to fill Little Prague

    By Wendy Weitzel | From Page: A7 | Gallery

     
    Yolo County real estate sales

    By Zoe Juanitas | From Page: A7

    Davis Roots hires new general manager

    By Special to The Enterprise | From Page: A8

     
    Comcast announces speed upgrade

    By Special to The Enterprise | From Page: A8

     
    .

    Obituaries

    Whitney Joy Engler

    By Special to The Enterprise | From Page: A6

     
    Valente Forrest Dolcini

    By Special to The Enterprise | From Page: A6

     
    .

    Comics

    Comics: Sunday, April 26, 2015

    By Creator | From Page: B8