Telescope Basics 5 (of 6): Learn the basics about barlow lenses for telescopes

Barlow lenses are an inexpensive – and often effective – way to increase the magnification and eyepiece collection of amateur astronomers. In this video, David Fuller of “Eyes on the Sky” takes the viewer through the various types, caveats and benefits with using them, as well as what to look for when shopping for one.



ahmed selman says:

I probably said that before but since I’m watching this video again I’d like to say it one more time: Thank you. 🙂

Tech know funda says:

I don’t know how to place eyepice in my telescope protos 90 ×50360 telescope

Eyes on the Sky says:

It only has a 650mm focal length, so with a 9mm eyepiece, you’re only getting 72x magnification. That’s fine for some star clusters and other deep sky objects (even the Moon), but it won’t make the planets look large at all. You really need either a 2x or 3x barlow, or some 3mm, 4mm or 5mm eyepieces to get sufficient magnification from that scope. It should give you nice wide field view of larger objects like M39, M45, M42, M31 and the Double Cluster though.

Gregory Bailey says:

still lost

Andrei Dinu says:

Thank you so much I was using the barlow lense wrong this whole time

magdanoz88 says:

Hi, David! Can you tell something about these Eyepieces + Filters + Barlow lenses kits (comes with these fancy aluminium suitcases)? I’m really thinking about buying one ot these – Celeston or Orion – doesn’t matter.

Cristian Franguloiu says:

Hello guys are new to the telescopes, my daughter received a 76 mm Firstscope and I would like to Barlow lens 3x or 5x buy using eye SR4mm and H20mm you think would be most appropriate?

michael carquez says:

LOVE IT! I never thought of putting my Barlow before my star diagional that is awesome!

cold_cold Days 03 says:


annette says:

Anyone know where I can get a long barlow?? I can’t find them anywhere, they’re all short ones

Luiz Pacheco says:

Hello David! Irecently bought a Meade LightBridge mini 82mm that came with a H20mm and a H9mm. I’m thinking in buying a Meade PL 4 mm multi-coated. This eyepiece would be good to see planets and nebulas with this scope? also could i use it with a 2x barlow lens? Thanks in advance!

clarence Castile says:

Very helpful or considering I never connected my telenegative

blastpeed says:

Thanks for the info, I’m gonna give a 3x barlow a try!

Eyes on the Sky says:

Are these eyepieces all Plossls? The 8″ scope can handle up to 400x magnification on the best nights of steady seeing, though you’ll often be limited to 150x or 200x most nights, which the 7.5 should provide (around 160x). Sounds like you might need more eye relief…??? A Zhumell Z-Series, Orion Expanse or Astro-Tech LER series eyepiece might make the observing experience better for you; it’s much easier to view through those ones in the shorter focal lengths of 4mm – 8mm.

Call Local says:

Hi guys, I have to ask because I didn’t understand your math equations at all in the video. I just bought the Meade Lightbridge 12. It came with a 26mm eye piece and a 35mm extender (Barlow I think). When I use the two together It’s very blurry – what am I doing wrong? Are these two not to be used together? I hope to hear from you soon. Thank you.

Hisham A.H says:

Hi David,
Thanks for the video;
What is advisable?single or 3 glasses Barlow for better view of planets?
With double or triple glasses you loose some light,with single you suffer of reflections,so after all,which one would you recommend for a better view and photography for a dark planet like Jupiter?

Jasmin Budhan says:

Hi David, I am ordering the Orion goscope II 70mm refractor should I get a barlow along with a 25% moon filter? Or will the Barlow create the same magnifications?

Keith Honaker says:

@eyesinthesky I have a celestron astromaster 114eq telescope and was thinking of buying a barlow lens for it. the specs of my scope says the highest useful magnification is 269x. My question is, if the barlow lens exceeds that magnification with a particular eyepiece, will it make my views impossible to focus? Will it just make a bunch of blurry planets etc?

Sam Hoff says:

What? it goes before my diagonal? So THAT’S why my eyepiece didn’t seem like it fit right. Thanks!

jack sparrow says:

very informative! thanks for the video. i am new to astrophotography and i hope you could answer this, if this kind of setup will work.
Refractor+barlow+dslr w/adapter. There is no diagonal. Will i be able to achieve focus?

Redfirebird 350 says:

I have a celestron 50 travel telescope with a 3x barlow and no matter what I do everything is not clear…about to throw the towel

Simon Rose says:

hi, great video, i have a problem.
I have a camera attached to a barlow x2 fitted to my small cassegrain, i have it all fitted into a .965″ to 1.25″ diagonal. i get a bright spot that fades from the centre like a large hazy star, would this be due to the step up diagonal?

Mark Montes says:

i am new to stargazing so i don’t even know how to attach the lenses to the telescope. i have a celestron cpc1100. is there a video out there that explains how to attach the barlow and lenses? thanks for any help, mark

Rocky Cool says:

Hey guys i have a question to everyone here, i see the Jupiter and its 4 moon from northern hemisphere (INDIA). Here is the question,

If Jupiter and its moon are in the horizontal plane which is same as orbital plane of Jupiter and also same as Earth and its moon plane, then when i see the moons of jupiter should not they be placed in vertical order rather than in horizontal order ? Because if they are placed in horizontal order does it mean they revolve around Jupiter in plane perpendicular to the orbital plane of the Jupiter ?? Can some one please explain these to me…

beProgMyFriend says:

I own a Celestron 130 telescope with 10 mm (33 x) and 20 mm (66 x) eye piece. I just wanted to know which barlow lens I should buy, which would improve the magnification without any degrade in picture clarity. Thanks

Riloo says:

oh thanks for telling me cause i was using my barlow lens opposite of my telescope for 1 month and thats why i was getting blurry image of the moon :DDDD

Ronald Reed says:

i have a refractor 900 mm telescope i received as a gift over forty years ago. i have not used it much over the last twenty years or so and finally was able too get the lens mixed up while trying too use it again., the barlow lens i thought had lens at each end. i ask not sure about this and need to put the correct lens back on the barrel of it. any help would be welcome..thanks.

Jesus Campos says:

I have an Orion FunScope which I received as a gift.

Specs (for those who don’t know); A reflector scope. Comes with an
Optical Diameter 76mm, a Focal Length 300mm; Focal Ratio f/3.9, and
comes with two 3-element Eye Pieces (20.0mm (15x), 10.0mm (30x)). Its
highest useful magnification 152x.

Recommend folks see his video on this scope: “Orion Funscope / Celestron
Firstscope review/comparison”

I love it’s portability and that sits nicely on my tripod, but like
everyone here, I would like to improve my experience.

I’m not a fan of wasting money on poor products, since sooner or later
it will cost me, but I neither want to spent a ridiculously amount of

Based on your videos (IMHO they are great introduction to this hobby!!),
I should consider a shorty Barlow fully multi-coated lens. Based on the
lenses I have, it should be a 3x or 5x Barlow lens.

My goals is to be able to see the rings and moons of Saturn. (Just like I
use to, with an old refractor scope I once had)

Amazon results gave me few results of brands I’m familiar with:

Celestron 93428 X-Cel LX 1.25-Inch 3x 3-element apochromatic Barlow
Lens (~$65)
Orion 8707 High-Power 1.25-Inch 3x 4-Element Barlow Lens (~$134)
Orion 8715 High-Power 1.25-Inch 5x 4-Element Barlow Lens (~$175)

Do you have any advice on these Barlow lenses, or should I consider a
different vendor/model for my FunScope?

Teboski78 says:

I started using a 3x Barlow lens with a 20 mm eyepiece and the image is a lot larger but I can’t get it to focus as well.

Sotiris Krol says:

Spend the extra money on a Apochromatic Barlow

Skandalos says:

A video about Barlow lenses that doesnt mention the proportional loss of brightness even once (as doesnt the whole series) … big thumbs down.

L812812 says:

So I have a 8″ dobsonian Skywatcher, and I currently own a 2x barlow lens. I want to purchase a x5 barlow lens for better viewing of planets such as Jupiter, Saturn etc. Would you recommend I get one or would that not work very well?

my 8″ is 200mm/1200mm. I have a few eye pieces. The ones I got with my scope are the 25mm and 10mm eyepiece. With the boxset that has the 2x barlow lens I got the 15mm eyepiece and 6mm.

MEGABOY240 says:

Hey there! Im planning to buy a Celestron firstscope 76mm… and its comes with two eyepices 15x and 75x….. Now my question is …. should I get a 2x barlow or a 1.5xto 3x variable barlow? And pls tell me what a variable barlow is along with pros and cons.. Thanks! Hope you see this and reply soon

Nick Cox says:

Hi guys! How important is it to place the barlow in the scope first as opposed to at the end, in the diagonal, and the lens or imager placed directly in the barlow?



Manuel Cortez says:

what are the elements when talking about brlows, it might be dumb for you guys, but im just learning.

bbaker904 says:

I need some help. I have been using newtonians for astrophotography using prime focus. This gave me the shortest focal length and fast shooting times. But great loss in magnification. So I bought a 2.5x short barlow. Now I have captured a bunch of deep sky images that are great. But due to medical problems my days of lugging around a large scope or over. I just bought a light weight refractor. A 102mm f6.9 to be exact. I do believe the focal length is 660mm. The scope has a 2 inch focuser with the 1 1/2 step down and diagonal. The main question I have now is what will be the best way to mount my camera? Can I use my 2inch 2.5x barlow direct in the 2 inch focuser and mount my camera direct? Can I mount my camera direct to the 2 inch focuser without the barlow. Or should I buy a 1 1/2 inch camera adapter and use my barlow like you showed in the video or completely forget about the diagonal? Or maybe buy an eyepiece that I can attach a camera to like the baader?

Mike Grant says:

Hey EOTS, great vid as always. Just wondering, I have a Meade 114eq 1000mm f8.8 bird jones style. So there is already a lens mounted inside the focus tube. Is this effectively a built in Barlow? I read on some forums that I should stick to dedicated eyepieces instead of using barlows due to this added internal lens. Do you have any opinion on this matter? Have you used a bird jones with a barlow? Thanks for any help…

Nicholas Taylor says:

I might sound dumb but I’m very new to astronomy. Can 2 barlows be stacked say a x2 and an x3 to make x5? I ask because I have a x2 and an x3. Thanks.

ssuley says:

A couple of questions:

1.) Does using a barlow impact the Telescopic Field of View ( TFOV)° ? For example my 600mm f-7.5 with a 10mm eyepiece with 82° AFOV gives me 1.36° of TFOV. If I were to add a 2x Barlow does that cut the TFOV in half to 0.68° TFOV?

2.) Does using a 2x barlow double the eye relief distance of any eyepiece? And does a 4x powermate quadruple the eye relief distance?

3) Does using a barlow impact the field stop diameter of the eyepiece in use? How is the value impacted?

Thanks for all your effort. Great videos. I learned a lot. ( a lot more to go)

DeathNote 7 says:

I have a Celestron Firstscope and I’m planning on getting a case with plossl eyepieces. Are they good to use with a the Celestron Firstscope?

Chowder Saki says:

Hi David, I wanted to ask you a question on my telescope. So it’s a Galileo telescope that has a D:76 and F:700 plus I’m using an eyepiece of 25mm but the problem is that the moon wasn’t quite as close as I’d want it to be so I recently got a 3x barlow and it doesn’t even show up good!!! Its super blurry no matter how close or far I move the magnification! please help!!!

Lewis Vallier Jr says:

I have an eyepiece that I don’t know how many if there’s lenses missing or not it is a SR4mm. how many lenses are there supposed to be in it


i have a 5x barlow lense and i cant focus in it has the black dot with the light around it, what will i need?? 114mm mirror

Ajinkya Ambavane says:

I am in plan to buy celestron powerseeker 60 az. But still confused rather ts give me real pleasure to watch the world or not. Is saturn is visible to this telescope? Could i see the asteroid belt or other planets? Please help me

Phil Olivetti says:

Wonderful video! Love these basics videos! so helpful.

Vidal Mand says:

I have a 3x Barlow for celestron 60az, the vision is blurred even if I adjust it precisely, it only happens in the Barlow lens, others work fine, is my Barlow lens defective?

Joe Joe joejoe says:

Hello guys I just started astronomy and when viewing some planets like Jupiter they are very bright and I cannot see the detail at all. Would a moon filter work to darken it so I can see some bands?

Kristian Alexandersen says:

Will it make any significant difference if i look through the telescope without the star diagonal?

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