The Orion E-Series Zoom Eyepiece makes it possible for even casual telescope users to reap the benefits of zoom eyepiece technology! It is able to change the telescope focal length from 21mm to 7mm or to any focal length in between, making it perfect for locating an object at low magnification and quickly zooming in to higher magnification for closer observation. Actual magnification range will depend on the focal length of your telescope. This Zoom Eyepiece works well for astronomical or terrestrial viewing in smaller refractors or Cassegrain design telescopes.

The E-Series Zoom eyepiece is complete with a 6-element design that gives you the experience of multi-coated optics and comfortably long eye relief ranging from 18mm (at 21mm) to 16.3mm (at 7mm). The apparent field of view angle ranges from 40 degrees (at 21mm) to 57 degrees (at 7mm). The 1.25" barrel is threaded for standard eyepiece filters, making this a very nice value, quality zoom eyepiece!

• The E-Series Zoom Eyepiece allows you to change magnification power without changing eyepieces
• You can adjust the focal length from 21mm to 7mm by twisting the eyepiece housing, providing you a variety of viewing magnification powers
• 1.25" barrel is threaded for use with like-sized Orion eyepiece filters