Choosing a Barlow lens does seem pretty straightforward, but there are a few considerations to keep in mind so that you get the best viewing experience.
- The first thing you should be aware of is that both eyepieces and Barlow lenses come in two different barrel sizes – the diameter of the eyepiece tube that fits into the focuser. Of course, you will need to select one with the appropriate barrel size for your telescope. Most standard telescopes and eyepieces have barrel sizes of 1.25 inches. There are however telescopes which require eyepieces and Barlow lenses of 2 inches. A few older and really inexpensive designs have the nearly obsolete 0.965 inch barrels.
- Be mindful of the existing eyepieces you have in your collection before purchasing a Barlow lens, as either the eyepieces or the Barlow lens may become redundant. For example, if you own a 20mm and 10mm eyepiece, a Barlow lens is unnecessary. The lens effectively converts the 20mm into a 10mm, so generally, you would not want eyepieces that are multiples of one another.
- As you have seen, Barlow lenses are designed in different magnifications, with the most common being the 2x Barlow lens. It may be very tempting to immediately go for the biggest magnification you can, but there are limits to how much magnification is useful. It is best to start with the lowest magnification possible, so the standard 2x Barlow lens is ideal for most users. A more powerful Barlow lens does not always suit a variety of telescopes, especially smaller ones.
It is also a common misconception that the more magnification the better the images the views. Realistically, the quality of the images relies on the quality of the telescope’s optics, including a reliable Barlow lens.
Best Barlow Lens Reviews
Orion 08711 Shorty 1.25-Inch 2x Barlow Lens
One of the great aspects of the Orion Shorty 2x Barlow lens is that it is a compact 3-inch accessory. This is half the length of traditional Barlow lenses making it convenient to store in your existing accessory kit.
The quality lens is multi-coated for the best light transmission, and the accessory effortlessly fits into place with two thumbscrews. Users love that Orion’s Shorty 2x Barlow lens reduces eyestrain and is super comfortable to use, as well as the fact that it is a quality but very affordable telescope accessory.Buy Orion 08711 Shorty 1.25-Inch 2x Barlow Lens
SVBONY Barlow Lens 5x 1.25″ Metal Fully Multi Coated Optics
SVBONY has the perfect Barlow lens for users with larger aperture telescopes. It offers 5x magnification for beautifully detailed observations of the Moon, planets, and deep sky objects. The SVBONY Barlow uses three elements, is fully multi-coated and has a high transmittance so you can be sure of sharply focused images.
This Barlow lens is sturdy and lasting with its aluminum build made for long term use. It has been designed for comfort and is a real steal.
Orion High-Power 1.25 Inch 2x 4-Element Barlow Lens
The 2x Barlow from Orion is another great lens for large aperture telescopes which hold up well under high magnification.
Thanks to using a 4-element lens design, this Barlow lens produces beautifully sharp and color-correct views without having to worry about aberrations. The black interior and blackened lens edges add better contrast to the views. The high magnification of the Orion 4 element 2x Barlow lens is ideal for the best views of the Moon and planets and works well for astrophotography too.
It is very comfortable to use, and the brass compression rings and rubber grip exterior hold everything securely in place.
It is a great, higher-end accessory.
Alstar 2″ 2.5x Barlow Lens – 2″ and 1.25″ In-One
This Barlow lens from Alstar has the handy feature of being able to fit both 1.25 and 2 inch eyepieces, as both adaptors are included. It really helps if you have a collection of differently threaded eyepieces that may not have gotten use otherwise.
It is made with 4 elements and is fully multi-coated to produce the best possible images under 2.5x magnification.
It is well made with brass compression rings to protect the barrel’s finish, as well as rubber grip for easy handling. It is a little more expensive than similarly powered Barlow lenses, but the convenience and quality offered make it a worthy choice.
Solomark 2″ ED 2x dual power Telescope Barlow Lens
Solomark offers this 2 inch 2x achromatic Barlow lens at a very competitive price. It is an essential accessory if you have eyepieces threaded for 2 inches, but also goes the extra mile with a 1.25 inch adaptor so that none of your eyepieces gather dust.
It is a two-element accessory, but rest assured that it does deliver color correction, brilliant sharpness, and clarity and brightness of images.
Though it provides a very comfortable eye relief, this Barlow lens is not limited to observations only – it is also perfectly suitable for astrophotography.
What is a Barlow Lens?
The Barlow lens is an accessory that pairs with eyepieces to increase the magnifying power of a telescope. It is named after its inventor Peter Barlow. A Barlow lens is a great addition to any telescope set up especially if you do not want to get extra eyepieces, as a Barlow lens effectively doubles your existing eyepiece collection.
Barlow lenses are very easy to use. Instead of placing an eyepiece into the telescope’s focuser, you insert the Barlow lens into the focuser and then connect the eyepiece to the Barlow lens.
How a Barlow Lens Works
The distance from the main mirror or lens of a telescope to the point where the rays of light are focused is the focal length of the telescope. Some telescopes have a short focal length while others have a long focal length. A standard telescope’s focal length usually correlates to the physical length of the tube. Modern designs could have short tubes (which make the telescope far more portable and compact) but still possessing a relatively long focal length.
Focal length is directly linked to how much magnifying power a telescope is capable of. Instruments with long focal lengths will produce more sharply focused images at higher magnifications.
A Barlow lens’s function is to essentially increase the focal length of a telescope. We can also see the genius of a Barlow lens by how it affects eyepieces. Depending on the particular Barlow lens, the magnifying power of an eyepiece is instantly doubled, tripled, or sometimes even five times as much as what it would be without the Barlow lens.
Remember that the smaller the number on the eyepiece, the more magnification it will provide. So if you had a collection of eyepieces that includes a 32mm, 25mm, and 10mm, adding a 2x Barlow lens would essentially expand your collection to also include 16mm, 12mm, and 5mm eyepieces. Whereas you would usually have to fork out quite a bit extra for three additional eyepieces, you need only spend once for a quality Barlow lens. Barlow lenses cost even less than the price of just one eyepiece!
You can read here for more on magnification, focal length, and how telescopes work.
Barlow Lens Pros and Cons
Pros
- Barlow lenses are a cost-effective way to increase magnification. They are often much less expensive than eyepieces.
- They help cut down on storage and maintenance.
- Barlow lenses allow a long eye relief, so those who wear glasses can enjoy a full field of view without having to remove their glasses.
Cons
- A lower-end Barlow lens is made with fewer elements or with lower quality material. Such a lens will show optical flaws, so it is always worth it to rather spend a little extra.
- More powerful Barlow lenses are not that effective with smaller telescopes. Smaller telescopes do not gather as much light to begin with, and over-magnifying the image only spreads the light and results in dim views.
How do Barlow Lenses Differ from Zoom Lenses?
Barlow lenses and zoom lenses are very similar and effectively do the same thing; therefore it is very easy to confuse the two. However, there are some basic differences between the Barlow and zoom lenses.
- There are some Barlow lenses that can be adjusted to different magnifications. Standard Barlow lenses have a fixed magnification of 2x, 3x or 5x. Zoom lenses, on the other hand, are capable of varying the amount of magnification.
- The field of view of a Barlow lens is usually smaller than on a zoom lens.
- All lenses are prone to optical flaws, one being chromatic aberration. Both Barlow and zoom lenses use several glass elements for achromatic correction. Zoom lenses typically have more glass elements than Barlow lenses because their changing focal length makes it harder to correct chromatic aberrations. The additional glass elements make zoom lenses bigger, heavier and pricier.
- Barlow lenses are definitely better suited for beginner amateur astronomers. They are simple to use and can often provide better quality views at a lower cost than zoom lenses.
Conclusion
The Barlow lens is an essential accessory to any stargazer’s kit as it is not only effective but very affordable and simple to use.