A guide to choosing the right Barlow telescope

A guide to choosing the right Barlow telescope

Blog Article

Named after the famous mathematician, Peter Barlow, a Barlow lens is an optical instrument used to increase the magnification of an eyepiece for visual astronomy or to increase the focal length of a telescope for astrophotography. This lens is placed between the eyepiece and diagonal for visual astronomy and between the camera and the focus tube for astrophotography.

Barlow lenses come in a variety of magnifications (typically between 2x and 5x) and increase the magnification of any eye placed in front of them. In this article, we will examine the performance and how to choose the right Barlow for the telescope. Stay with us.

How does the Barlow lens work?

Simply put, a Barlow lens increases the effective focal length of a telescope. This lens diverges the light before entering the eyepiece, which increases the magnification of the image. Each lens has a fixed magnification factor (for example, 1x, 2x, etc.), which is multiplied by the ocular magnification and obtains a total magnification.

How to use the Barlow lens

Fortunately, these lenses are very easy to use. As we said above, this lens is placed between the eyepiece and the focuser. So, before putting the eyepiece in place, insert the lens and then insert the eyepiece.

Choose an eye.
Place the barlow in the focuser of the telescope and secure it in place.
Insert the eyepiece into the lens and secure it in place.
Adjust the telescope with the help of the focuser to make the image clear.
Enjoy the picture you see.

Some telescopes, such as refractors and SCTs, usually have an oblique lens, which allows you to change the arrangement of the optical instrument. For example, instead of putting the Barlow in the focuser, you can put the oblique lens in the Barlow and the Barlow in the focuser.

This means that the eye position does not change and is placed in the oblique lens. Conversely, changing the position of the barlow will change its magnification.



When to use Barlow lens?

This type of lens is an excellent tool for visual astronomy and astrophotography and has various uses:

1. Increase magnification
If the telescope eyepiece does not have the magnification you want, we recommend using a Barlow lens. Adding a 2x or 3x lens increases the magnification of the device and enables you to see different objects.

2. Upgrade the optical system
Combining the Barlow lens with different eyepieces allows you to get more out of your eyepiece collection and have more magnification at your disposal. The cost of purchasing a Barlow lens to combine with your eyepiece set will be significantly less than the cost of purchasing multiple eyepieces.

3. Maintaining eye comfort
Many strong eyepieces do not have a large eye relief distance and the user has to place his eye very close to the eyepiece. The Barlow lens, along with a lower magnification eyepiece, provides a greater comfort distance for the user, which is especially useful for bespectacled or children.

Although there are many benefits to using Barlow lenses, there are a few things to keep in mind:

Lower exposures: Although optical instruments have advanced and transmit more light, more layers of lens elements (eg glass) in a Barlow lens may produce lower exposures. This disadvantage is especially evident in slower (higher f-stop) telescopes.

Great magnification isn't always better: the Barlow lens magnifies the subject, but also exacerbates any blurring that may be present. As a result, the image may be blurred.
Possibility of vignetting: Whenever you change an optical system, it is possible to face new problems like vignetting.