Barlow Lenses & Focal Extenders
- Barlow or Extender Barrel Size: Threaded
- Barlow or Extender by Magnification: 2X
- Back Focus: 73mm
- Compatibility: FS-60CB, FC-76D, and FC-100D refractors
Barlow lenses are an essential part of any telescope accessory collection. Invented in 1834 by Peter Barlow, the Barlow Lens increases the magnification of your telescope. The most popular barlow lens is the 2x barlow lens. By using a 2x Barlow Lens you are cutting the effective focal length of your eyepiece in half. For example, if you are using a 20mm Eyepiece with a 2x Barlow Lens you will effectively cut the focal length to 10mm, therefore doubling the magnification of whatever telescope you decide to use.
Barlow Lense focal extenders are great telescope accessories because when added to your telescope accessory collection they essentially double the magnification range of your eyepiece assortment. For example, if you have focal lengths of 40mm, 25mm and 10mm in your collection and you add a 2x Barlow Lens then you will have effectively widened your collection range to 40mm, 25mm, 20mm, 12.5mm, 10mm and 5mm. Adding a Barlow focal extender lens is a great way to increase your eyepiece magnification range while saving money!
Barlow Lenses are easy to use, all you have to do is take the eyepiece you want to use and insert it into your barlow lens and tighten the set screw. You then take your eyepiece and barlow lens combination and insert them into the diagonal of your telescope. Barlow Lenses come in 1.25" and 2" formats. The 1.25" barlow lens is the most common, however the 2" barlow lens is becoming more and more popular because is allows more light to enter through the eyepiece.
If you don't have a barlow lens you should seriously consider adding one to your telescope accessory collection!