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Equipment Library

The Seattle Astronomical Society maintains a library of small and medium size telescopes that may be checked out by members in good standing. If you are new to astronomy, this is an excellent way to learn how to use a telescope and to begin viewing the wonders of the night sky, without having to invest immediately in a telescope of your own. To check out a telescope, please check out our equipment available for loan.

If you have any questions about borrowing equipment, or do not see a specific piece of equipment please reach out to our Equipment Manager.

See the complete equipment list in alphabetical order.


You can narrow your search of our equipment library by selecting any one of the below keywords.

Astrophotography Beginner Binoculars Camera Intermediate Maksutov Newtonian Refractor Schmidt Cassegrain Visual

All our equipment is currently on loan to other members.

Available Eventually

The following list of equipment is currently loaned out to a member, and may include other members waiting to also borrow.

  • APO/ZWO Advanced CCD Astrophotography Kit

    Currently there are 2 requests to borrow this.

    This astrophotography kit  is designed help capable amateur astronomers develop the skills requried to image deep sky objects. It is not suitable for beginners. Some prior observing or imaging experience with simpler equipment, such as a star tracker and DSLR camera, is strongly recommended. The borrower needs to understand how to align and use an equatorial mount. 

    The borrower must supply a laptop computer and install the necessary software to operate the camera and associated equipment.  

    The kit includes a Meade Series ED APO (apochromatic) 80mm refractor, a Celestron Advanced VX telescope mount, and a capable ZWO color CCD camera.  Beginner astrophotographers are encouraged to consider requesting and using our Star Tracker/DSLR kit or the the entry level (but capable) "APO/Ultrastar Astrophotography Kit",  prior to requesting this kit.

  • Celestron C102 Acromat Refractor

    Currently there are 3 requests to borrow this.

    102mm f/10 Equatorial Refractor

    The Celestron C102 is a 102mm aperature, achromatic refractor with a sturdy XLT equatorial mount.. The long f/10 focal ratio provides a sharp image and is ideal for viewing planets, the moon, and bright deep sky objects.

  • Orion 80mm ED Refractor

    Loan ends in 93 days on May 24, 2024 (Friday).

    High Quality 80mm Refractor. Optical tube only at this time; the Mount is out for repairs. 
    Note for experienced users: The optical tube can be used with any mount with a Vixen-style saddle. Contact the Equipment Manager for more information. 

    The Orion 80ED is a small, general purpose refractor telescope that will give sharp images of the moon and planets as well as the brighter star clusters and galaxies. ED glass improves the image contrast compared to a traditional acromat. The Twilight I Alt-Az mount is easy intuitive to use.

All our equipment is in good condition!

Telescope Types

Types of telescopes

Copyright NIAAS, North Ireland Amatuer Astronomical Society

What are those numbers?

Types of telescopes

Copyright 2008-2012

The f-ratio is the focal length divided by the diameter of the telescope. Magnification is the focal length of the telescope divided by the focal length of the eyepiece.


To find the f-ratio of a telescope 10 " in diameter with a 45" focal length:

Divide 45 " F.L. by10" D. to get an f-ratio of 4.5.

Compute Magnification

First, convert focal length to mm: 45" = 1146 mm, then:

1146 mm focal length divided by 35 mm eyepiece equals 33 magnification.

More Information

If you are interested in learning more about telescopes, we recommend: