When buying parts for a telescope, the lens is one of the most important components to consider. This is because it can affect your overall field of view and your image’s clarity. An important addition to your optical system is a Barlow lens. In this article, we will detail how to use a Barlow lens.
People can install a few different types of lenses onto a telescope to enhance its overall effectiveness. One of the most popular is the Barlow lens. They have remained a fan-favorite even though it has been around for centuries.
So why do people choose to use a Barlow lens? And how exactly do you attach it and use it with a telescope? Here is everything you need to know about this type lens to get a better picture of the planets. As well as planets a more magnified view of other objects can be produced.
What Is A Barlow Lens?
This type of lens is named after the mathematician Peter Barlow who first created the lens in the 19th century. They are a divergent lens that create an optical system that reduces the focal length. In effect, they reduce the focal length of the eyepiece. As a result, there is an increase in the magnification level.
The lens will therefore create a divergent ray of light that positions the eyepiece’s exit further outwards, granting it a better magnification while also increasing the eye relief, making the image much clearer and more vivid.
How To Use A Barlow Lens
Choosing The Right Lens
Before you purchase a Barlow lens, you’ll first want to decide which type fits your requirements.
Essentially, the eyepiece’s focal length will be divided by the factor of the lens. For example, if you were to pair a 10mm eyepiece with a 2x Barlow this would be equivalent to a 5mm eyepiece.
If you were to have a 25mm eyepiece and used it with a 4x Barlow lens, you would have a 6.25mm eyepiece.
Therefore, you will want to decide on a Barlow lens that will limit your focal length enough to allow the telescope to acquire the magnification level you want.
Because of this, you’re going to need to decide what you intend to use the telescope for. More specifically you will need to know what level of magnification that you require. Always keep in mind that a high magnification may not deliver a better viewing experience.
There is a maximum usable magnification that you should be aware of. This magnification is unique to the telescope model that you are using.
20mm is usually considered as the perfect number for astrophotography and expansive vistas. In comparison, 5mm eyepieces will provide high power magnifications and are therefore best for observing planets and the moon.
We recommend going with the 2x Barlow lens since this is the most common. It will instantly double the magnification of any eyepiece you connect.
Attach The Barlow Lens
The good news is that when you choose the type of lens you want to use, attaching it to the telescope is extremely easy. It can be done in just a few seconds. A Barlow lens fits between a telescope’s focused and the eyepiece.
You might be accustomed to dropping the eyepiece into the focuser to attach it. However, with a Barlow lens, you simply need to drop the one in instead before connecting the eyepiece.
Benefits To Using A Barlow Lens
While they are most popular among astrophotographers, a Barlow lens is slowly becoming seen as the standard for most telescope users, and there are a few reasons why they are seen as so useful.
Increased Magnification Levels
The primary reason people decide to use Barlow lenses is that they cut down the eyepiece’s focal length. This increases the telescope’s available magnification levels.
These features make these types of lenses versatile. They can be used with your favorite eyepieces to gain a new level of magnification. As a result, they are an economical way of expanding your available magnification levels.
Fits Most Barrel Sizes
A Barlow lens fits into any standard 1.25 or 2 inch telescope barrel. This is the same as most eyepieces suiting a standard telescope that hasn’t been specifically modified or altered. As a result, you can attach one easily.
Variety Of Magnification Options
Barlow lenses come in various magnification levels, ranging from 1.25x to 5x, giving you a tremendous amount of choice on how much you want to limit the focal length and improve the magnification levels.
Because these options are so specific, as long as you know the exact magnification level you want to use, you can adjust the eyepiece right to the exact number.
Cheaper In The Long Run
Buying a single Barlow lens can save you from buying multiple eyepieces since it gives you an easy way to adjust the exact focal length and magnification level you would like to use, saving you a lot of money down the line.
Saves A Lot Of Space
Because you also won’t need to carry around multiple eyepieces at once, buying a single Barlow lens saves a lot of space in your bag. This will make it much easier to take a telescope out for camping or hiking, and as we all know, there are already enough parts to carry as it is.
Negatives Of Barlow Lenses
Like with anything in life there are no free lunches. There is a price to pay for the convenience of using a Barlow lens.
One of the largest cons of using a Barlow lens rather than an eyepiece providing the required magnification is the narrowness of the view. Also, it is easier to exceed the maximum magnification that your telescope and/or conditions can support.
Because you are introducing more glass in the optic train, the view is a little dimmer. More glass will introduce more imperfections that will affect the image quality.
Adding more length to the focuser and eyepiece can result in more wiggle causing imperfections and frustration.
Summary
There are so many reasons why the Barlow lens has remained so popular ever since it was first created. The main reason is because of how much it can improve the magnification levels of an eyepiece. It also saves you a tremendous amount of money and storage room. All things considered it is an extremely handy tool that you will want to pick up for yourself.
Additionally, a Barlow lens can be easily attached to a telescope, meaning as soon as you buy it, it will be ready to use in just a few minutes.
Hi, my name is Jason Anderson, and I am a Physics Professor. Ever since I was a kid, I’ve been fascinated with space, the universe, the moon, you name it. I spent hours and hours at the planetarium close to my hometown, wondering what else could be out in the universe.
Since then, I’ve been an avid stargazer and astronomer, and love nothing more than spending my time charting stars, observing planets, and finding constellations.
This is why I decided to start Telescope Guru. I only wish to share this fun pastime with the world. With this site, I hope to answer all of your questions relating to astronomy, telescopes, and stargazing.
