Barlow Lens - Complete Overview and Function

[@1stcomment700]

I was a little hesitant to watch a whole 19 minute video but the way you explained it with so much detail made learning fun and enjoyable. I wish my college professors were more like you

[@pummyy]

What a legend. Starting with basics on what they are and why you need them. Great content. Thank you !

[@chaitanyavashistha446]

Best explanation ever on internet. Thank You from all of astro community. And we are also proud on your Jupiter and Refrector diagram.

[@Malignus68]

Yeah, his explanation is far beyond what I expected to see. He did an awesome job.

[@AstroBlender]

Glad you enjoyed it, thanks.

[@snakerafi]

I can say you did the best straight to the point no BS video with real views. This is one of the few I can show to my kids and they get an idea what is all that about.

[@AstroBlender]

snakerafi Glad you enjoyed it!

[@Bippy55]

March 2021 - OMWord!! You had me with the laser lines and the two lens " () )( >• " to show how they affect rays of light. Advice: Please don't underestimate your drawing and illustration skills. You did a great job. Now we need another video to talk about eyepiece filters: red, blue, and a 'moon filter' or 18% light reduction. "Optics Is Cool!"

[@noreaction1]

Is it better to put the barlow lens closer to the sensor compared to filters? Or vise versa

[@mireazma]

15:26 An even simpler explanation is: 2X lens = 4x less light because it's 2x for each dimension. We have a 2 dimensional sensor :)

[@MrFlextor]

Yes, it is not the fault of an existing coating and it´s quality to make objects dimm when using a barlow ( yes the effect is there but with very small impact ), it is the f-ratio increase which affects the brightness of the view! So for example shooting a picture with ISO 200 and f/11 gives you the same time value like shooting the same situation under same conditions at ISO400 and f/16. That means a full step in the f-ration ( which is exactly a full step in between f11 and f16 - same from 1.4-2-2.8-4-5.6-8-11-16-22 ) doubles the time or needs twice the sensitivity to get the same brightness, that is the magic behind, NOT the coatings which have a very low impact... To make it exact, the full-step or down in the f-ratio row is the sqare root of 2 , the numbers above are appoximate values :-)

[@bobsbarnworkshop]

I’m just getting back into astronomy after close to 50 years. My wife gifted me a Celestron 8se for Christmas so I’m ready to go! Great explanation of the math and light loss in a Barlow. I only have a 25mm eyepiece to start but plan on a couple more like maybe a 15mm and 10mm and a Barlow 2X. I need a couple filters including a solar. Back in 1970 I photographed the solar eclipse made famous in the song “You’re so vain” through a Sears 3” refractor with a solar filter and a 10mm and a Polaroid camera on a tripod lined up to the eyepiece! But most of the shots turned out great!

[@DuderinoDeux]

V powerful scope mag wise. Get a lens corrector and much higher eyepieces too for wider views. Plossls are great. Barlow great for blowing up Jupiter and Saturn. A good refractor 700-900mm a great companion.

[@jeffreygilbert2628]

Great video! Without a doubt the most in-depth description I've seen thus far, keep up the great work. -J.G.

[@AstroBlender]

Jeffrey Gilbert Thanks, I appreciate it!

[@bobmarshall1066]

A great article on Barlows, thank you. However, I Would like to make an important point with regard to the so called brightness of the image as you discussed. Ok, yes a Barlow, even fully multi coated will reduce the light a little, but and here's my point. You used the same exposure and ISO setting on the camera, but, as soon as you introduce a Barlow, the whole system will be slower photographically. So if you use the same exposure and ISO setting, of course the image will be less bright, or underexposed. F/8 becomes F/16 or F/32 and so on. Visually, there won't be too much difference at the same magnification, or a longer focal length eyepiece. Please don't overlook the fact that some of us still do visual astronomy :)

[@backyardskygazer]

I cant thank you enough for posting this and saving me some money. I am new to the hobby and have a nester 8se as well but from what I saw in the video that lens is not for me just yet, shall we say. Thank you so much again for posting this video.

[@johngiromini5745]

Very nice method of explaining Barlow features. When I want to photograph from a 12" DOB, I use a 2x Barlow to push the focal point further back to accommodate the camera position. Otherwise, one can't obtain a focused object.

[@AstroBlender]

John Giromini Glad you enjoyed it!

[@filipesilvestre6214]

Thanks for making this video. I like the dark circle on Jupiter!

[@AstroBlender]

Glad you like it!

[@_traubenkuchen_]

Its the shadow of one of the moons i think :D

[@andelkoloncar4791]

Probably the best explanation so far, GREAT job!!

[@AstroBlender]

Anďelko Lončar Glad you enjoyed it!

[@august3777]

I'm looking to buy my first telescope for deep sky imaging, and I just learned about barlow lens, so this video helped me a lot. Thank you for explaining It all.

[@AstroBlender]

Buttermilk Biscuits Glad you found it helpful.

[@jimtekkit]

Brother, your explanation is excellent. If the basic principles are this simple then why doesn't anyone explain it as such? I feel like a lot of reviewers get caught up in the subjectivity of viewing experiences and neglect to explain the fundamentals of how optics work. And that no amount of quality or design tricks or brand marketing can overcome the inherent disadvantages. That's why so many amateur astronomers believe that a 6mm lens with a 5x barlow is the best viewing experience.

[@Pouncerman]

Wow that was very good! I thought all a Barlow did was magnify the image on the diagonal mirror. I'll try putting it in front of the diagonal just to satisfy my curiosity. Thanks for a lot of good knowledge.

[@WarbirdPylonRacer]

Is there any difference to using a 2x barlow with a 20mm eyepiece vs just switching to a 10mm eyepiece?

[@MM0IMC]

Reminds me of the old teleconverters back in the 35mm SLR days, the doubled the image size, but halved the light arriving at the film plane. Image quality wasn't as sharp as it could have been. Inverse Square Law also applies.

[@bharatisgreate]

Great explanation buddy, and it was fun with full of information. thank you for the your detailed guide. Lot of love from India to you!!!

[@vyli1]

Wow, this was such a fantastic explanation and so detailed. Amazing.

[@MountainFisher]

I have a C6-N, great scope, or at least mine is, although I noticed in the first month the secondary kept going out of collimation. I figured out not to pick up the scope with the front cap off, thus keeping me from grabbing it by the front rim pulling the vanes on that side knocking it out of collimation. Cradle it to install on the side sitting mount. My first reflector. I learned a lot about Barlows from this video. I saw my view dim when I used a Barlow and this certainly explained why. Also taught me how to slow down my F5 when using a really bright Orthoscopic eyepiece.

[@Ivanzizek]

Good video, can you tell me what barlow lens is the Best for beginner telescope and that price is not expensive

[@BlazeByte21]

Hi! If I use high powered eyepiece without Barlow and a low powered eyepiece with a Barlow, both have the same magnification. Which one will produce a brighter image?

[@kmason7914]

What would happen if you added a focal reducer?

[@donaldhalvorsen4135]

Thank you for all of your hard work Simon.

[@BobtheScienceGuy]

Nicely done. If you need a 1 min exposure and add a 4x Barlow you would need 16 min exposures. Can you take 16 1 min exposures and get the same effect?

[@l.mendes8208]

Excellent explanation! Congrats!

[@AstroBlender]

You’re welcome!

[@zygmuntziokowski7877]

Question are you use 1.25" or 2" barlow lines?

[@musikmantracollections7037]

Can u explain if i use 2x barlow how to. Focus with diagram... I am confused as u said double the focal length then we have to use long telescope.. earlier i m using 700 m fl telescope.

[@morganmitchell4017]

Great video. Clearly a lot of effort went into it so it's a shame you're only in the hundreds of views. Subscribed though!

[@AstroBlender]

Morgan Mitchell Thanks for your support!

[@TechnoEsoterica]

30k+ now though!

[@jasonnikolic]

@@TechnoEsoterica and it's doubled in 4 months (60k+)

[@knightclan4]

Almost 87k after a year. Slow and steady for educational videos. Now if he hired a model in a bikini to talk Barlow , he might have gone viral. There’s a thought

[@GalaxyArtMedia]

Hello. Niceg formula, but it can get you confused when you first see it, I am used to calculate the stops of light depending on the new focal ratio number that you will have with a specific barlow lens. But actually using this formula could make the calculations more easy to make.

[@randommadness1021]

How do you change the exposure times? Thanks.

[@richardbarnes3665]

What kind of lasers did you use?

[@CarolinaSkyAstronomy]

I like to use a 2x for lunar and a 3x for planetary and yes you do have to turn the exposure up more but you get a better view of the planets with a 3x

[@danielfinch362]

I'm knew to this but I just commented I don't think you'd get much luck with more than x3 Barlow lens.

[@glennsubawalla9884]

Thank you slymin for all the info on barlows a very good effort put in by you.

[@AstroBlender]

GLENN Subawalla Glad you enjoyed it!

[@bicycleninja1685]

That laser example is pretty great! Also, the illustration is not too shabby.

[@djsundayrides4869]

Great video what if I just wanted to look a the planets would I still need a Barlow lens and would that just make the planets clearer ?

[@AstroBlender]

DJ Sunday Rides No, you don’t need a Barlow lens. You’ll find a Barlow will increase magnification but your view will be a bit more blurry depending on sky conditions.

[@djsundayrides4869]

@@AstroBlender Thank you for your help new to this I hope I brought the right one lol

[@arcvidelos8008]

Does a Barlow with a 1.25" barrel cause vignetting on eyepieces that exceed a certain apparent field of view?

[@psycronizer]

I have recently bought a 8 inch Dob, and only have the 10 and 25 Plossl that it came with....so I want to know a bit more about the Barlow...there are x2 and x3 and even a x5 Barlow available is there an optical quality reduction if going for a x3 or x5 over the x2 ?..it just seems to me that it's too good to be true, that simply putting in a x5 Barlow is going to produce an image that is just as sharp as non Barlowed... comments ? what would you suggest in terms of planetary viewing...needless to say I will also be buying other lenses in the future as well...my Dob is 200mm main mirror and 1200mm focal length, so 400 times mag is the limit..how close to that theoretical limit can i get when viewing the planets, I want to squeeze as much magnification out of it as I can !

[@AstroBlender]

It really depends on sky conditions. I have never used a 5x barlow, and never will because for visual use anything beyond a 3x barlow just isn't useful for me. A 5x barlow is typically used for planetary imaging in areas with very stable skies. The 2x barlow is the most practical for everyday purposes. The 3x is pushing it a bit for me, but for imaging it works occasionally.

[@danhilz1629]

Fantastic explanation. I learned a lot.

[@hooper365]

I found this video extremely helpful and well made thanks 🙏👍

[@AstroBlender]

Glad to hear it!

[@IGATECK]

Great video, what kind of adapter you used to mount the t3i? Thanks

[@funkydevil13]

Hi. I have celestron eq 130. I want to see planets and nebula. So suggest me barlow for that. 2x or 3x. Thanks in advance

[@APN34Z]

I got the same scope and bought the eye piece kit, seems that the more magnification u put into it the more blurry the image becomes, im disappointed

[@DirkDirk1983]

@@APN34Z eyepieces that come in a kit useally are not of the best quality.

[@APN34Z]

@@DirkDirk1983 Hi bro, yeh well i only paid £55 for the Celestron 94307 kit, is there anything u could recommend and i might return this

[@DirkDirk1983]

@@APN34Z so you have a 15mm kellner and a 6mm plossl. I suggest you'll upgrade the kellner 15mm. But I need a bit more info. What is the telescope you are using and will you be using it for planets or deepsky?

[@DirkDirk1983]

@@APN34Z wait. You have the same scope as funcky devil. Let me make a new message when i get home from work

[@johnnolan8074]

Thanks for the info. Curious if you use a 2" Barlow with a 11/4 " eyepiece. Is there any benefits to that?

[@AstroBlender]

John Nolan Not really besides you have the option of using 2” eyepieces.

[@johnnolan8074]

@@AstroBlender thank you much. Clear skies

[@anthonypla7134]

Clear explanation was very helpful, however, pie are round not squared

[@Jupitor108]

Great video, really informative and useful!! Thank you !!

[@AstroBlender]

Glad it was helpful!

[@muhammadazeem7538]

Which telescope did you use to take image of the Jupiter?

[@jessale]

🤣 😂

[@mertus4395]

Amazing in-depth video! I learned a lot, thanks a lot :D And don't worry for your fantastic drawings, they're great too lol

[@AstroBlender]

Thank you very much! Haha

[@andonrangelov8844]

I got a question about the barlow lens. I got spherical prime mirror reflector telescope with short focal length of 300mm (mirror diameter is 76mm) if I use a x2 barlow is it going to reduce the spherical aberrations? I mean if it enlarge the focal length then may be it also reduce the spherical aberrations?

[@TwoPancakes]

i wanted to see what would happen if you would put the concave lens first and the convex lens second. Wouldnt that flatten and magnify the image?

[@GTGeorgeW]

great video Cody !, -- QQ -- any chance you can link the lens kit you used?

[@IsmaelMartinezPR]

I stumbled on this video, and it seems these lenses are about the same as a teleconverter in photography. Why would you use ISO 800 and 1/1600, why not start at lower ISO. Is it to double the focal length in the time of the exposure. totally new to this.

[@sanpol4399]

Absolutely great video. The laser rays were so didactic !

[@AstroBlender]

Thank you, I am glad you enjoyed it!

[@bluename4]

what would the effect be, if combining a Focal Reducer and a Barlow Lense together?

[@mosesrodriguez1494]

Thank you for the lesson

[@CONFUCIUS-f2x]

Excellent presentation.

[@AstroBlender]

Thanks!

[@ruthlessadmin]

That was more than I ever needed or even wanted to know. Thanks!

[@AstroBlender]

statikreg Lol no problem.

[@G3RMZONE]

i saw on another video that recommends placing the barlow lens before the 90d elbow, does it make a difference where the barlow is placed?

[@danielfinch362]

Nice question, I do hope someone answers.

[@AstroBlender]

As a general rule of thumb if you insert a barlow before a diagonal you will get more magnification, but your equipment might not be so secure with all the weight, so most put it after a diagonal. For imaging I usually insert my barlow first since my planetary camera doesn't weight that much. I would experiment and see what works best for your set-up.

[@aritramahapatra6959]

Sir I have a question about Barlow magnification how can I measure the Barlow magnification I said this bcz I bought a 5x Barlow but I received only 3x Barlow sir pls tell how to calculate Barlow magnification??????😭😭😭🙏🙏🙏

[@bobminion198]

I have celestron starsense 130 mm reflector telescope. Could you recommend the best barlow lens for my telescope? Thank you.

[@kimbaldun]

x3 or x5

[@magnusengevik750]

VERY informative video, thanks!

[@AstroBlender]

You're welcome! I am glad you found it helpful!

[@frankkenyon798]

Slymin, Another great video! I couldn't help but notice you have an Explore Scientific diagonal on your 8 SE this time instead of the Celestron you recently reviewed. Can you compare the 2, please.

[@RA-wn3qh]

This was a really great explanation . Thanks !

[@rob2estonia]

The lasers earned you an automatic like.

[@TheUrbanAstronomer]

Nice in-depth video!

[@AstroBlender]

Thanks, I am glad you enjoyed it!

[@MicoDominiqueNixon]

What brand and model of telescope are you using?

[@MicoDominiqueNixon]

At the beginning of the video*

[@davidbarson2048]

nice explanation.

[@Quoutub]

I am surprised that nearly nobody in the comments noticed that the brightness explanation is wrong. A barlow or teleconverter doesn't reduce the amount of light one captures from an object. It makes it darker, but it doesn't reduce the amount of light from an object.

[@RichardPhilbin]

Excellent video !

[@technologyandyou296]

Really awesome 👏🏻 Buddy you explain things very well 👌🏻

[@donaldhalvorsen4135]

So if you used a diagonal, the light would Astro bend.

[@richardturner6981]

I can clearly see the difference between the Barlow lens and the other lens and to me it's like why bother to use a Barlow lens at all? You would use a Barlow lens if the Moon is very bright it seems to me. I also forgot about the mathematics that's involved in even amature astronomy. I'm absolutely terrible in mathematics. Right now i have a Celestron Powerseeker 50 AZ telescope and i'm having a terrible time calibrating the finder scope. Can you give me some help please? Thanks.

[@melangkoh4184]

hey, have you ever tested the Svbony 66 degree wide-angle budget-eyepieces?

[@dankahraman354]

Is there a way of precisely calculating how much I would have to rack out my focuser to achieve a new focus point with a barlow lens? I tried to image Saturn last night with my 7" f/15 Maksutov and a 2.8x Klee Barlow but I didn't do anything to the focuser ( i had tested it in the daytime and I could see the top of an power insulator...so I didn't worry about it) long story short: I couldn't see anything on the laptop screen. I thought both the guide scope and main scope were pointing to the same exact location...what did I do wrong?

[@dankahraman354]

@@doseofgaming5863 No too far out or in focus....

[@doseofgaming5863]

@@dankahraman354 ooooh, okay

[@dankahraman354]

​@@doseofgaming5863 jerk?

[@oliverdesouza5741]

So a Barlow lens is almost exactly the same as a teleconverter in photography, and suffers from exactly the same issues (losing light and acuity). If astro-photography is the goal, it would be interesting to compare the quality of some Barlow lenses with camera TCs, which are typically around $200-300 for a decent (Canon / Nikon) 2x version.

[@PrepperStateofMind]

Great video. Learned a lot

[@thedonahoes]

This is the best explanation of a Barlow I've seen. However, doesn't it make the images dimmer because you're effectively shooting through an f/25 instead of an f/10? I agree that the more optical elements you add, the more scatter you will have, and more light lost, regardless of coatings, But I would expect a slower optical system to produce dimmer images for a given exposure.

[@thedonahoes]

Oh... You address this around 17:00 . Should've waited to the end of the video to comment. Sorry.

[@Malignus68]

Spectacular job on this video and explanation!

[@AstroBlender]

J L N Glad you enjoyed it!

[@explosivebrickstudios2693]

Thank you so much for this tutorial, you probably saved me a lot of money! ♥️

[@AstroBlender]

ExplosiveBrickStudios Glad you found it helpful.

[@martinmcbrown6437]

@@AstroBlender Hey mate, question from me as a new telescope owner: should I invest into 4.7mm 82degree eyepiece or should i use barlowed lens?

[@humlakullen]

Awesome video. Thanks:-)!

[@AstroBlender]

You're welcome, I am glad you enjoyed it!

[@crdave43]

Awesome video, I learnt so much, Thank you

[@Janet_Airlines802]

What camera do you use?

[@JuanGutiérrez_cl]

Excelente!!!

[@mrgonads2040]

Conservation of energy. There's only a fixed amount of energy (photons in this case) entering the telescope. Increasing magnification comes at the cost of luminosity. The total energy has not changed, just how it has been apportioned.

[@AstroBlender]

Mr Gonads Correct.

[@jessale]

7:30... OMG, seeing that Jupiter makes me happy. I love that Jupiter. 😆 🤣 😂

[@brokenstring21]

I appreciate you and your channel. Godbless.

[@davidmcfadden1763]

Aha! That explains why the ring nebula was so dim with my barlow! It was dim to begin with, in my C8 se, so when I barlowed it, it all but disappeared!

[@AstroBlender]

david mcfadden Oh yes, definitely!

[@daslolo]

And you can formate compensate for bad atmospheric conditions by using both eyes: binoviewer. Good only for bright objects

[@palmereldrich]

I will be curious if you address the Barlows best function. Boosting it. Achieving a pushed exit pupil. Edit: nope you did not what a missed opportunity. Doing boosting achieves magical things. For an extremely short ocular a much more comfortable view is attained. The more energy into the Airy disk the higher the content of contrast in which to address image darkness. I've taken an apo in spectacular seeing to ~900X simply by pulling out my Baader zoom several millimeters out of its normal Barlow seating position. Really missed an opportunity to tell your followers a little known facet of Barlows.

[@henri-julienchartrand3387]

I agree with Peter on this one. HJ from Montréal, QC Canada.

[@swaldron5558]

Thanks for your interesting information.

[@AstroBlender]

Thanks for watching!

[@girijaa1]

I recently bought a Gskyer 600mm/90mm Refractor from Amazon. It came with a 3X Barlow lens. After initial setup of the telescope and trying out the 3 eyepieces that came with the telescope, I realized that the 3X Barlow lens degrades the image in the viewfinder. So I decided to go back to Amazon and looked for a 2X Barlow lens with good reviews and bought the SVbony 2X Barlow lens. This did not improve image quality at all. The best, sharpest image I could get, was with a bare telescope and a 25mm eyepiece. I don't think I will ever use the 10mm or 5mm eyepieces, because its basically impossible to find anything using those short eyepieces with tiny openings. My question is why the Barlow lenses degrade the image so much? I setup the telescope outside in bright sunlight and focus on an object a mile away and I can get a super sharp clear image with only the 25mm eyepiece. I am disappointed that the Barlow lenses I have is basically useless. I had a clear view of Jupiter and Saturn last night and for the first time in my life, I could see the moons of Jupiter clearly. I would really have liked a larger magnification so I can see the rings of Saturn, but I am stuck with what I have. Is there anything I can do to improve image quality and magnification? Thanks

[@AstroBlender]

Pieter Roelofse To properly utilize a Barlow lens you would need to upgrade your telescope to something better with better optical quality. The same with the Barlow lens. A good Barlow runs anywhere from $80-200. An Explore Scientific AR-102 would be a massive upgrade in optical quality, and with a good Barlow things would be more crisp.

[@dennisammann9104]

I was lost in space when he said, “Pie are square.” 🤔 Everyone knows pie are round. 🥧 😀🤣

[@redfireroush]

Very helpful video!! Nothing like cramming a little more math into my aging brain. ;)

[@jerrykapchan103]

Thanks Slymin!

[@Weathership]

Nice job,,,,

[@stevemacdonald2303]

I had a 5in dobson I used 3 Barlow and it was clear

[@SaereeNon]

Very helpful, thanks a lot.

[@alexwkinney]

Great video, thanks!!!

[@AstroBlender]

Glad you liked it!