Equipment Library

The Seattle Astronomical Society maintains a library of small and medium size telescopes that may be checked out for a period of 1 month 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.

All our equipment is currently on loan to other members.

None of our equipment is loaned out to any members.

Currently Unavailable

The following list of equipment is not available to members until we are able to replace or repair parts.

Edmund Astroscan

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

This telescope needs repairs and is not currently available for loans.

The Edmund Scientific Astroscan 4 1/8" telescope comes in a basic package that includes the telescope, a unit power red circle sight (Rigel Quik Point), 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 Astroscan has a focal length of 445mm and makes a great "grab and go" scope requiring virtually no setup.  Unfortunately the telescope is slightly but permenately out of collimation and is not suitable for hig power viewing, but it works OK with the provided eyepieces.. A low power eyepiece (16x) provides a three degree angle true field of view and a medium power eyepiece provides 25x. 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 does not quite resolve Saturn's ring system.

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: