What is the difference between Barlows, Focal Extenders and Focal Reducers?

This is a video about Barlows, focal extenders and reducers in a bit more detail highlighting the difference between these designs to help you with your purchase decision. Check it out!

Contents of this video:
0:00 - Intro
0:27 - Barlows
5:21 - Focal Extenders
7:39 - Focal Reducers
09:23 - Conclusion

More information on the Tele Vue 2x 1.25” Barlow

More information on the Explore Scientific 2x 1.25” Focal Extender

More information on the Tele Vue 1.25” Focal Reducer

More information on the Omegon 1.25” Focal Reducer

NASA Apollo Saturn V Lego set:

Thank you for your support!

[krystianciesiun]

Hi! please add more vid’s. The most substantive and comprehensive yt channel on astronomy. ;)

[SpectreLX]

Truth: every additional lens - reduces the image quality! 👍👍👍
Thank you!

[edf]

Hi Bogdan. This is the best comparison video of Barlow lenses, focal extenders and focal reducers that I’ve ever seen on YouTube. You did an excellent job in explaining the differences and benefits and considerations. Great job. I also just watched todays video on getting ready for Saturn’s viewing opportunity later this month. That was another fine production which I found very informative and interesting. Thanks for sharing your knowledge with the community.

[schotoka]

Thx for the video. I got myself an omegon reducer to experiment with my MAK. Just waiting fo clear skies.

[wessauder]

Thank you for such a detailed explanation. What a timely video! I bit the bullet and bought the 2" 2x Explore Scientific Focal Extender recently and it worked extremely well - I was nervous but the quality of the build, flexibility with my eyepieces and great star gazing experience really showed me I bought a great quality piece worth the price (NEAF Sale!). I was curious what the difference between the Barlow and the Extender were and I'm really glad I went with the extender. For reference, I have a vintage C8 Celestar Deluxe which I just purchased as well as several luminos eyepiece (7, 10 and 23mm) along with a 2" Celestron Dielectric diagonal. Clear Skies!

[SuzanneWhitehead-otfi]

Helpful and detailed explanation! Thank you!

[vitalie]

Thank you so much for explanation!
I have one 14" Dobsonian F/4.6 with 1650mm FL and one 12" LX200 SCT F/10 with 3048mm FL ... using a 30mm 82° ES eyepiece I can see beautifully the entire double cluster in Perseus only in the 14" dobsonian...but with the same eyepiece on the 12" SCT ... only one cluster at the time .... the same for Andromeda Galaxy...with a shorter focal length I see more of it. I don't do Astrophotography...I'm more of a visual observer... I guess I'm gonna get one of those Celestron Focal Reducer/ Corrector F/6.3.

[kellytaylor]

I like the Vernonscope
MDB 1 1/4”
they thread into your eyepieces that have standard or Vernonscope ( Brandon ) threads.
My scopes are all F/9 or longer ratios.
The MDB 1.25x or 1.5X can be combined to make a
3X or a 2.75x or 2.5X
The cost is very good
and the glass is excellent.
After viewing for many many hours at the eyepiece of my scopes.
The MDB gives me the ability
to see how good the seeing is on any given night.
I have other eyepiece brands.
When I want to forget about the glass and just view all I can see with the conditions
There is a Brandon Eyepiece in my scope.
Then maybe a MDB Vernonscope Barlow as well.
More talk of exit pupil and
F/ratios need to be discussed.
Framing your viewing object with the FOV of Eyepiece in use.
Eyepieces and good filters give you choices most did not know they had.
When one of the world’s best visual observer was asked the question. ( How did you deal with the color on those old refractors at Harvard? )
His response was.
#11 yellow filter.
Also a #8.
I learned a lot about filters.
The UV/IR filter should be in every visual observer’s Eyepiece case.
I believe in Not letting a camera and computer have all the fun.
Get a good comfortable position and study what you look at.
Let your eye adjust to what is there!
Most of all have fun!
Over 40 years of viewing.
1, 000’s of hours at the eyepiece.
For me it never gets old.

[DoronTshuva]

great video, when I see more then 2 that are 100% I usually subscribe.
thank you for the good work.

does more Barlow give more eye relief?

[lavers_]

thanks for this information. Excellent channel!

[MountainFisher]

I seldom use Barlows except with my larger Orthoscopic eyepieces, brings in planets very well. I never thought about focal extenders at all not knowing the difference, well now I know and at present do not find myself in need of one, but I'm getting an Apo 102mm F7 and we'll see how that works out with 2" eyepieces.
I have noticed simple polarizing filters or a cheap broadband helps kill fringe on planets and the Moon when placed in the Barlow. I use a Shorty from time to time plus the tall TV 2x.

[alexsoma]

Thank you for yet another great video! I have a request if I may: could you review the Oberon series from Omegon? I cannot find anything on those anywhere... And I would love to see a review from you. Anyway, thanks again for all your great work!

[editplayerog]

can I Make Spotting Scope Since Spotting scopes are so Expensive if we see celestron gosky Brands i Want To viewing birds, mountains And little bit of Astronomy like moon Saturn and i have A Objective lens of 500mm focal length and 70mm diameter So Can I Use Short Focal Length tube To Use it under 100mm tube with Barlow ?

[ivanluhi]

Nice! Exactly the explanation I was looking for!
Is a focal extender preferable to a Barlow for astrophotography/EEA?

[jasonspringfield]

Thank you for the video. I have a C8 SCT. I'm trying to do planetary imaging using the ES 2X focal extender and a DSLR plugged into it, but I can't get it to focus. I noticed other astrophotographers tend to use Barlows combined with an astrocamera screwed on for planetary imaging, and I'm thinking that I should buy a barlow with threads. Can you, or some of the experts in the comment area, explain if Barlows should be used for astrophotography instead of focal extenders and why? Thanks for the help.

[elray]

Very thorough, excellent review. Would a focal extender be brighter than a Barlow or a PowerMate?

[mihaitaene]

Buna dimineata, Dl. Damian . Sunt incepator si am un refractor Bresser Taurus 90/900 mm. Cum as putea sa l imbunatatesc pentru observarea DSO ? Am 2 oculare Kellner de 20 si 4 mm. Ma puteti ajuta ? Multumesc frumos . O zi buna !!

[anthony]

I have a Discovory Sky T50 and it comes with a H20mm and F6mm eyepieces. Can i buy and use other eyepieces or it depends on the diagonal mirror?

[sudarshan]

A totally beginner question - can I build a complete eyepiece set with a single eyepiece (of say around 3mm exit pupil) and multiple barlows 1.5x, 2x, 3x and focal reducers etc?

[kevkef]

I have a question about the Focal Extenders. Is it possible to use it in combination with a barlow lens? For example, I would use the 2x barlow lens with a T2 Ring adapter for my DSLR camera. I already try it with a 2x barlow lens, T2 ring adapter and a DSLR camera to capture the moon. I have a 750mm telescope. But I just recently found out that I couldn't find Saturn (August 27th) even with a barlow. Hopefully the community can help me out. And if it's possible/compatible, that would be easier to make the choice.