What is a barlow lens?

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Your telescope may come equipped with an accessory called a barlow lens. A barlow is nothing more than a sleeve with an additional interior lens that can either double or triple an eyepiece’s magnification. For example, a 20mm eyepiece used in a 1000mm focal length telescope would deliver 50X magnifying power. If you add a 2X barlow lens, the same 20mm eyepiece would now deliver 100X magnifying power.

If your telescope did not come with a barlow lens—don’t worry. This is just a simple and inexpensive accessory you may wish to add some day. It is far from a necessity!

Next Page: Do I need special filters?

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