eyepiece projection vs barlow

Eyepiece Projection VS Barlow: Choose the Right One!

Just as your planetary or nebula photography can’t wait, you are also concerned about your choice. And we know it can be a hard one.

So, you want to know about eyepiece projection vs Barlow?

Between eyepiece projection and Barlow, if you prefer higher focal length and magnification, go for eyepiece projection. This will ensure clearer and also more vivid photography. However, if you want to avoid chromatic aberration, Barlow is more adept at it. Also, it will costs less compared to the eyepiece projection.

But knowing just this much won’t serve your cause. Don’t worry though. Cause we’ve written a whole article about this just for you. 

Let’s jump right in!

Quick Comparison

Whether you’ll use eyepiece projection or Barlow depends on various factors. But after much research and analysis, we’ve narrowed it down to four factors. Based on these factors, you’ll be able to come to a definite conclusion.

FeaturesEyepiece ProjectionBarlow
Focal Length 40 mm distance added with the eyepiece focal length ( 3mm – 50mm)2X to 5X of normal focal length
MagnificationDependant on the eyepiece and telescope focal length2X – 5X
Chromatic AberrationChromatic aberration existsChromatic aberration is reduced
PriceCheck Price on AmazonCheck Price on Amazon

But we do understand that such brief information can still leave you confused. Thus, we have elaborated on all these topics. Be sure to check it out whole.

Before moving forward let’s take a look at this graph for a more comprehensive view:

Eyepiece Projection and Barlow chart

Now let’s move onto the details. 

Detailed Comparison

Choosing the right thing for your astrophotography is of utmost importance. We get that. And that’s why we have provided a detailed description of their factor-based comparison. 

After going through it, hope your issues will be resolved. 

Focal Length:

As we all know, the length of the telescope is considered the focal length. So what does focal length do in a telescope? Basically, focal length adjusts the field of view and magnification of the telescope.

If the focal length is more, then the magnification is increased. Although the field of view is decreased in this case.

the focal length
Source: cloudynights.com

On the other hand, If the focal length is reduced then the field of view increases. But in this case, there is not much magnification.

The basic idea of eyepiece projection is to connect the eyepiece with a camera. Of course, the lens of the camera has to be removed. 

In its place, the eyepiece is attached. So, the focal length in eyepiece projection depends directly on the eyepiece.

So, how can I find the focal length of the eyepiece? 

The focal length of the eyepiece is written on the eyepiece next to the magnification. However, if you can’t see it there, there is another way to calculate it. By dividing the focal length of the telescope by its magnification you’ll be able to calculate the focal length of the eyepiece. 

The typical range of an eyepiece is 3mm – 50mm. So this is also the range of focal length for eyepiece projection. 

On the other hand, Barlow works in a different manner. Barlow can be used in both telescopes and in cameras for astrophotography. 

Mainly focussing on astrophotography, Barlow increases the focal length of your camera. So, what is the average focal length of a camera?

The average focal length for a standard camera lens could be considered 30mm – 50mm. It is mostly similar to the human eye. However, the focal length for a professional camera is much more. This range could be considered as 50mm – 100mm.

So what Barlow does is, increase this focal length. If the Barlow lens is 2X then it will increase the focal length to double. If you have a 100 mm focal length lens and you use a 2X Barlow with it:

New focal length = 2 * 100mm = 200 mm

If you use other Barlows then just the multiplication factor will change. In these cases, you can choose between Plossl or Kellner. Both are good choices but be sure to check which one is ideal for you.

By now most probably you’ve got which one you should use. Based on focal length, the eyepiece and the camera lens are quite similar. But by using a Barlow you can extend it further to your choice. Although eyepieces have their own magnification.

This can extend the quality of the image further. We’ll cover it next.

Winner: It’s a tie as both of them are quite adept. 


In both eyepiece projection and Barlow, magnification is used. By this the image is further broadened and clearer. But both of them have a different process.

In the case of eyepiece projection, we have the general approach.

magnification by telescope focal length
Source: astrobackyard.com

In telescopes, we can calculate the magnification by telescope focal length and eyepiece focal length. Simply by dividing them. So, if the focal length of your telescope is 1000mm and you have a 10 mm eyepiece, 

 Magnification= 1000mm / 10mm = 100

Thus you have a high magnification factor. The only tricky part here is attaching the camera properly with the telescope. Like the model Nikon D5600. So, how to attach a camera to a telescope? You can use a T-ring to lock the camera body to a telescope and an adapter to thread it onto T-ring.

But Barlow doesn’t have such methods. It comes with definite magnifications. Typically, a Barlow can be of 2X, 3X, and 5X. 

These are used in astrophotography. It increases the magnification of the camera to get a clear shot of your desired celestial object. 

So, if you need a higher magnification then go for eyepiece projection.

Winner: As the eyepiece projection has higher magnification, it’s the winner here. 

Chromatic Aberration:

A big problem in astrophotography is chromatic aberration. What is chromatic aberration? Chromatic aberration is an outline of distorted color around an object in a photograph. 

In astrophotography, sometimes you’ll see an outline of distorted colors around a planet. This is most commonly seen in eyepiece projection. In it, the tangible outcome of different electromagnetic radiation wavelengths is the main issue. 

They are refracted at marginally different angles, leading to a lack of focus. This in turn causes distorted colors.

But in Barlow things are different. So, does Barlow reduce chromatic aberration?

Yes, Barlow reduces chromatic aberration. To reduce chromatic aberration, Barlows have a second convex element. This results in very little distortion of the image. In some cases, premium Barlow also has a third element. It is of extra-low dispersion glass which further decreases chromatic aberration. 

So if you want a clear Astro pic with no distortion, definitely go for the Barlow. 

Winner: As Barlow reduces chromatic aberration it’s the winner here. 


If you are worried about the price, then there is good news and bad news. 

The good news is with your DSLR in hand, you can spend just 25$-30$ on Barlow. And you’ll be all set.

Now for the bad news. You have to spend about 220$ for eyepiece projection. Why? 

Cause you need more than one thing for the setup. Along with the eyepiece you’ll also need T- a ring, T-Adapter, and an extension tube for the setup.

This causes a rise in price. Here is a detailed approximated analysis:

T- Ring + T Adapter  40$ – 55$
Extension Tube140$ – 160$
Total price = 200$ – 220$

The price of the eyepiece is excluded here because you can take it from the telescope. However, if you might need one. 

So how much does eyepiece cost? it’ll cost you an extra 2000$ – 2200$ ( 25 mm eyepiece). For different focal lengths, the price will differ.

So, if your pocket isn’t feeling too healthy, try to go for the Barlow.

Winner: As the Barlow costs less yet gives a good value for it’s money, it’s the winner.  

Final Verdict: Which One is Better?

By now you should’ve understood which one is the right fit for you. If you want a clearer image with higher magnification, go for an eyepiece projection. 

However, if you are concerned about the price and chromatic aberration, go for Barlow. It’s as simple as that.

That’s all regarding this debate!

Frequently Asked Questions (FAQs)

Is 10 mm telescope lense stronger than 20 mm?

Yes, a 10 mm telescope lens is stronger than 20 mm. In fact, a 10 mm eyepiece has twice more magnification as a 20 mm eyepiece. Mainly a smaller number on the eyepiece means that it has higher magnification. Although in different scopes, the magnification of the same eyepiece can vary. 

What can I see with a 70 mm telescope?

Yes, you can see with a 70 mm telescope. Although 70 mm could be considered a small aperture, it has quite a moderate power.  You can easily see various celestial objects like dozens of Messiers, planets up to Jupiter and Saturn and so much more. It’s also possible to take really eye-dazzling pictures of the Moon using this.  

What eyepiece to use for viewing stars?

For viewing stars the Plössl eyepiece would be perfect. Its design is mostly suitable for observing star clusters and nebulae. Although it has a disadvantage. Their eye relief diminishes with the reduced amount of focal length. A 25 mm and 15 mm pissol eyepiece can be a great addition to your astrophotography setup. 


Now let’s hear about your opinion. Were we able to solve all your queries about eyepiece projection vs Barlow?

Here is some extra advice for you. Whatever you might choose between the two, be sure to find the right camera for your astrophotography. 

If there is anything else on your mind, be sure to comment down below.

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