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.

  • Orion SkyQuest XT8 Dobsonian

    Currently there are 4 requests to borrow this.

    8" Newtonian Reflector on Dobsonain Mount.


  • Orion StarBlast 4.5

    Currently there are 3 requests to borrow this.

    Compact 4.5 Inch (114 mm) Newtonian Telescope

    This Orion StarBlast 4.5 reflector telescope is a good beginners well as a nice "grab and go" scope for advanced observers. Its lowest power (18x) provides an expansive 2.2 degree field of view that is ideal for locating and viewing large star clusters and galaxies. The SAS Equipment Library has mounted a StarBlast tube assembly on a stable, easy to understand Alt-Az mount and tripod. This configuration is different from the Starblast 4.5 sold commercially. (Our mount and tripod were salvaged from a bigger but non-functional telescope)

    .An Orion EZ Finder II "red Dot" reflex sight is provided to aim the telescope. The user looks at the sky through the viewing window of the EZ Finder and sees a red dot, like a heads up display on an airplane windshield. The user then moves the telescope until the red-dot is aimed at the intended area of the sky.

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: