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 XT10g - Computerized GoTo Dobsonian

    Currently there are 1 requests to borrow this.

    Important: Contact the Equipment Manager for approval before requesting this heavy bulky telescope..

    10 Inch GoTo Dobsonian Telescope

    The XT10g is a 10" aperture Newtonian telescope in a motorized Go-To mount.  A red dot reflex sight finder and eyepieces are included. 

    This is a  very heavy and bulky telescope and it is usually loaned for extended periods. The base is large and weighs nearly 40 lbs. The optical tube weighs 30 lbs and is about 12 inches in diameter by 48 inches long. It may require 2 people to lift it and a bigger vehicle to transport it.

  • Orion SkyQuest XT10i

    Loan ends in 70 days on February 04, 2023 (Saturday).

    10 Inch Dobsonian Computer Aided (PushTo) Telescope

    Important: This is a heavy and bulky telescope and it is usually loaned for extended periods.  It may require 2 people to lift it and a bigger vehicle to transport it.

    The Orion SkyQuest XT10i IntelliScope is a 10" aperture Dobsonian Reflector with a Push-To computer system for aiming the telescope. 

  • Orion SkyQuest XT8 Dobsonian

    Currently there are 1 requests to borrow this.

    8" Newtonian Reflector on Dobsonain Mount.


Available by Request

Contact the Equipment Manager for more information on borrowing the following equipment.

  • AWB 130mm Reflector

    Note  This item is being serviced and it is not available for check out.

    Table Top Newtonian Telescope

    This telescope is suitable for all ages and is a good choice for viewing the moon, planets, and bright deep sky objects. It has a Dobsonian style mounting that is compact and intuitive to use. A red-dot reflex sight and a set of eyepieces is included.. It is designed to be placed on a small table or similar support and does not come with a tripod.

  • Edmund Astroscan

    Note  This item is being serviced and it is not available for check out.

    Table Top Newtonian Telescope

    Note: This scope has a small collimation error but it works well up to about 30x for wide field viewing.

    The Astroscan telescope is suitable for all ages. The package includes the telescope, a red circle refles sight (Rigel Quik Point) for aiming the scope, a cast-aluminum tabletop base that's padded to prevent scratches on sensitive surfaces, a user's manual, two eyepieces, and a carrying bag. The telescope is intended to be placed on a table and does not include a tripod.

    The Astroscan has a focal length of 445mm and makes a great "grab and go" scope requiring virtually no setup. It is a good telescope to use with children. Unfortunately the telescope is slightly but permanently out of collimation and is not suitable for high power viewing, but it works well with the provided low power eyepieces. A 16x eyepiece provides a three degree angle true field of view. A 25x eyepiece is also provided. The Astroscan provides good views of large star clusters and nebula, such as the Double Cluster, the Andromeda galaxy, and the Great Nebula in Orion complex, all of which can be seen from the suburbs of Seattle. It will show Jupiter and it's moons but 25x magnification is not enough to resolve Saturn's ring system.

  • Orion StarBlast 4.5

    Note  This item is being serviced and it is not available for check out.

     The Explore Scientific Twilight Alt-Az Mount is out for warranty repair. Contact the Equipment Manager for an estimated availability date..

    Compact 4.5 Inch (114 mm) Newtonian Telescope

    This Orion StarBlast 4.5 reflector telescope is a good beginners telescope. Advanced amateurs will appreciate its portability and its low power, 2.2 degree field of view, which is ideal for viewing large star clusters and galaxies. It is mounted on a Twilight II Alt-Az mount that is intuitive to use.

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: