Telescope Accessories

Other than a telescope and mount, you need to have a few accessories such as extra eyepieces, a good finder, a map, and perhaps a light-pollution filter.  Here are some ideas for the best accessories to complement your telescope…

  • A finder scope.  A small low-power telescope mounted on the side of the main tube of the telescope to help you point your telescope to a desired object.  Finders come in a variety of magnifications and apertures such as 6×30, 8×50, and so on.  You can also find “non-magnifying” finders.  They are not telescopes, but rather aiming devices with small red dots or reticles that help you point your telescope at the sky.
A magnifying finder

A magnifying finder

  • Eyepieces.  An eyepiece magnifies the image made by the objective lens or mirror. You need at least one eyepiece, and two or three with a short, medium, and long focal length is better to give you a range of magnification.  More about eyepieces here and here and here.
televue

Televue eyepieces

  • Star Diagonal.  The position of the eyepiece on refractors and compound telescopes makes it very awkward to look at objects higher in the sky.  So most observers use a “star diagonal”, a little mirror mounted in a metal housing to help you look at right angles to the direction of the telescope tube.  Newtonians/Dobsonians do not require star diagonals.  Most telescopes, especially telescopes intended for new stargazers, come with these essential accessories so you can get started right away… one or two eyepieces, a finder, and a star diagonal.  Double check before you order.
A star diagonal

A star diagonal

  • Light Pollution Filter.  Very useful devices that mount on the back of an eyepiece to remove unwanted light from low and high-pressure street lamps, while passing light from nebulae.  They do not help with visual observation of stars or galaxies, but only with emission and planetary nebulae.  More about light pollution filters here… 
  • A red flashlight.   A red LED flashlight helps you see your maps and hardware in the dark. Red light ensures your eyes remain dark-adapted and sensitive to faint light.  And if there’s a lot of ambient light where you observe, try an eyepatch to keep your observing eye at peak sensitivity.  More about making sure your eyes are dark-adapted in this article…
A red LED flashlight for astronomy (credit: Astronomics.com)

A red LED flashlight for astronomy (credit: Astronomics.com)

  • Barlow Lens.  Not an essential accessory, but a Barlow lens, when used with an eyepiece, doubles or triples the magnification of that eyepiece.  Effectively you can get two magnifications with each of your eyepieces.
  • Star maps.  The best telescope in the world won’t do you much good if you don’t know how to use it or where to point it. Get a star atlas such as The Pocket Sky Atlas by Roger Sinnott .  It costs about $30.  Or you can get a planetarium app for your computer or smartphone.  The application called Stellarium is free for a computer and just a few dollars for a smartphone or tablet