Go Out:  Look Up!

A Guide to the Sky, Telescopes, and Telescope Programs

Home How a Scope Works Using a Scope Note to Parents Aiming a Scope Using a Finder Eyepieces Using a Zoom Fun Equipment


Zoom Eyepieces

Skip to Using the Celestron Zoom

The narrow field of view of high power eyepieces makes it difficult to locate an object.  One technique when using a non-guided scope is to use a low power eyepiece to find and center an object and then switch eyepieces to a high power eyepiece for detailed observing.  Some disadvantages to this technique include

  • the hassle of having to switch eyepieces
  • moving or bumping the scope during the switch
  • dropping or losing eyepieces

Using a zoom eyepiece allows you to locate an object at low power, center the object, then zoom in at higher magnification.

The picture to the right has two circles representing the fields of view through a Starblast 6i and a Celestron 8-24mm Zoom eyepiece.

The inner circle is at 8mm, its highest magnification (94x).

The outer circle shows the eyepiece at 21mm, its lowest magnification (31x) and widest field of view (approximately 1 degree). 

At low power both the M81 and M82 galaxies can be seen at once (this is a favorite site)

Note that at high power only one of galaxies can be seen at once.

Using the Celestron 8-24 Zoom

The Celestron Zoom installs like any other eyepiece and should be secured by tightening the thumbscrews on the finder.

The Zoom has an arrow and a focal length scale for easy reference.

To zoom in (higher power), grab the eyepiece by the knurled section and twist to the left (counterclockwise).  8mm is the highest magnification.

To zoom out (lower power, wider field of view), grab the eyepiece by the knurled section and twist to the right (clockwise).  24mm is the lowest magnification and the widest field of view.


Questions or comments? Email:Jeff Martin