How to Use the Barlow Lens With the Sky-Watcher SK909AZ3 Refractor Telescope

A Barlow lens is used when you intend to increase the magnification power of your telescope. Named after Peter Barlow (1776-1862), a professor of mathematics at the Royal Military Academy at Woolwich, England, this special lens provides relief to the human eye while viewing objects in the sky. A refractor is a device that changes the way of light beams by passing it between two transparent materials of different densities. Here is how to use the Barlow lens with the Sky-Watcher SK909AZ3 Refractor Telescope:

Difficulty:

Easy

Instructions

1. Note that you can insert the Barlow Lens in two ways for better view from the telescope. The lens can be placed between the focuser and the eyepiece in a reflector or between the focuser and the diagonal. By doing so, you get greater magnification. By placing the Barlow lens between the focuser and the diagonal, the 2X lens can work as 3X.

2. Loosen the thumbscrews to insert the Barlow lens near the focuser. Fix the thumbscrews when done.

3. Use the Barlow lens by inserting it between the focuser and the diagonal of the refractor telescope. By doing so, the light beams will bend at each end due to the Barlow lens. This change makes the light rays converge at a focal point and you will be able to make the image of a distant object brighter.

4. Insert the Barlow lens between the diagonal and the eyepiece of a refractor telescope. By doing so, the light beams will bend at each end due to the Barlow lens. This change makes the light rays converge at a focal point and you will be able to make the image of a distant object brighter.

5. Refocus the telescope after adding or removing the Barlow lens.

Tips & Warnings

• Make sure that you keep all the thumbscrews in place and do not interchange their positions to ensure that the assembly is proper.

• Use only the special lens paper to clean the Finderscope and eyepiece.

• Loosen and tighten the screws only in daylight (or at a place where there is sufficient light) and in an area where you have enough space to ensure that you don't loose any of the screws.

• Do not clean the lens or any optical surface unless you are familiar with or you know the correct treatment for that particular optical surface.