What Is A Barlow Lens?

If you are interested in astronomy or even photography, then you may have heard of a Barlow lens.

This is a type of lens that works to increase the focal length of an optical system, and basically magnifies the image. This is why a Barlow lens is most typically used in telescopes, photography and even microscopes.

As an astronomy enthusiast, you will want to ensure that you have the best equipment to star gaze, discover planets and enjoy the night sky, and so a barlow lens should be on your list of apparatus. 

If you have not yet uncovered the wonder of the barlow lens, then we are here to open your eyes and tell you why you need one!

What Is A Barlow Lens?

A Barlow lens is a cheap and effective way to magnify an image. These are most commonly used with telescopes, as they work to increase the magnification of the telescope eyepiece for better viewing.

The Barlow lens was actually invented during the 19th century by a mathematician, astronomer and optician called Peter Barlow.

The lens works to improve the eyepiece’s magnification, which can be done two or even three times, meaning you will be able to see so much more with your telescope with a Barlow lens installed. 

The magnification of your telescope will generally rely on the focal length of the objective, then divided by the focal length of your eyepiece. This means that to improve your magnification, you will need to either decrease the focal length of the eyepiece or increase the focal length of your objective. 

With this in mind, the Barlow lens works to increase the effective focal length of the telescope in order to work. 

How Does A Barlow Lens Work?

The Barlow lens works as a diverging lens that will increase the effective focal length of your optical system.

It works as an extra layer of glass, as another optical element to your telescope, that will improve the image, by extending outwards the cone of light from the first part of your telescope. This means that your eyepiece will be able to view a much larger, more focused image.

A Barlow lens works when it is placed between the telescope objective lens or mirror and the eyepiece, so that it can increase the magnification of the telescope by 2 or 3 times.

The lens is connected directly to the eyepiece, and is highly effective in increasing the focus and detail of an image, yet is much more cost efficient than purchasing a different eyepiece. 

If you are ready to up your telescope game, then you will need to know which Barlow lenses are the best, and worth investing in. 

What Are The Best Barlow Lenses?

The main thing that you need to consider when purchasing a Barlow lens is whether it will effectively fit the eyepiece of your telescope. Most Barlow lenses come in either a 1.25 or a 2 inch standard size, so you should be able to find one with a universal fit that will be suitable for your eyepiece. 

In addition, Barlow lenses come with different capabilities. The most common Barlow lenses will offer a magnification of either 2X or 3X, however, you can purchase some with a magnification of up to 5X or more.

That being said, the most common Barlow lens will have 2X magnification, which works perfectly to improve the image quality that you need to see.

The best all-rounder Barlow lens is the Bysameyee Barlow Lens. It is cost effective, offers 2X magnification and fits a 1.25 inch eyepiece:

Our runner up is the Orion Shorty 1.25 inch Barlow lens:

You can also try the Celestron Omni 2X  Barlow Lens:

Or the Celestron 3X Barlow lens for greater magnification:

For the most cost efficient and simplest to use, try the SVBONY Barlow Lens:

Using A Barlow Lens

Once you have selected your Barlow lens, you will need to know exactly how to use it to get the most out of your new equipment. 

To use a Barlow lens, all you have to do is insert it into the focuser, just as you would an eyepiece. Then, you actually insert your eyepiece into the Barlow lens for it to work. It really is that easy!

However, you should remember that it is always better to use a 2X Barlow lens because the more powerful lenses do not have great results with smaller telescopes.

This is due to the poor amount of light that these telescopes are able to pull in, and so a 5X Barlow lens will not be able to see much with good clarity. 

That being said, if you do have a larger, more impressive telescope, then there is no harm in trying out a Barlow lens with 3X magnification for greater exploration of the sky. 


A Barlow lens is an essential instrument to keep in your repertoire if you are an astronomy enthusiast. They are relatively cost effective, and are priced much lower than eyepieces, yet have great focal power. 

With a Barlow lens, you are able to effectively double or even triple your telescope’s magnification, without having to purchase any extra eyepieces!

With these types of lenses, you are able to increase the focal length, clarity and detail of the images that you seek, making this little contraption and essential piece of equipment.

Gordon Watts