A simple drop in Barlow Lens that triples the magnification of the eyepiece.
This Barlow lens would be fitted with an eyepiece to increase the magnification of the telescope by three times.
Astronomical Barlow lenses like this one are rated for the amount of magnification they provide. Usually a Barlow lens will be either 2x or 3x magnification.
A Barlow lens is housed in an eyepiece tube that is one Barlow focal-length long, so that a focusing lens inserted into the end of the tube will be separated from the Barlow lens at the other end by one Barlow focal-length,this gives 3x magnification more than the eyepiece would have produced alone (so a 12.5x eyepiece would be changed to 37.5x).
An image that is magnified in this way is not always clearer, and a poor quality Barlow lens can make an image worse. Image quality depends on the weather and the quality of the lenses being used. For these reasons this Barlow lens features a 3 Element Apochromatic Lens for superior sharpness and colour correction, fully Multi Coated Optics to increase contrast and decrease internal reflections and a Brass Compression Ring.