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Looking for a good quality and affordable Barlow

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#1 Pcbessa

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Posted 10 February 2019 - 08:02 PM

Hi!

 

I am looking for a good quality Barlow, for my newly bought F4.7 scope, an Orion XT10i (10inch Dobsonian).

As this is a fast scope, I am searching for a good quality Barlow to be used combined with some good quality eyepieces (they will be either ES68 or used Televue). The scope only came with two Plossl 25mm and 10mm.

 

I heard good things of the 1.25" Orion Ultrascopic Barlow 2x. Any experience with it?

 

Is the Celestron X Cel Barlow also of good quality? Would the 3x be equally good?

Thanks,

 


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#2 M11Mike

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Posted 10 February 2019 - 08:07 PM

Go with the Celestron 2X Ultima - 3 element - APO - Made In Japan.  They are on CN's quite often for around $50 (used).  It's a EXCELLENT barlow - hard to beat for the $$$.  M11Mike  


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#3 CeleNoptic

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Posted 10 February 2019 - 08:26 PM

If you are planning ultra wide field eyepieces than a telecentric Barlow like 2x ES Focal Extender can be recommended. I have the Meade version of that and it's actually the only Barlow I use. Basically, the three element budget Barlows like Ultima work pretty good, but have serious limitations. I have a number of various Barlows and aware that telenegative Barlows especially shorties like Celestron Ultima vignetting long FL 82*AFOV (14mm+) and 68*AFOV (20mm+) eyepieces. In shorter FL UWA eyepieces telenegative Barlows increase spherical aberration (kidneybeaning). Telecentric extenders are free from those problems.


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#4 AxelB

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Posted 10 February 2019 - 10:24 PM

I just acquired a used X-cel x2 barlow. I haven’t had the opportunity yet to do any critical testing, mostly because of the clouds or bad seeing. A quick check with an ES68 24mm , this barlow and my AR127 f6.5 refractor didn’t show any obvious vignetting so that’s a good start. Still, I’ll need to follow a very dim star (while focussing against field curvature of my scope) to figure out if it’s clear or not.

As soon as the sky conditions will allow, I plan to test it thoroughly on my C8. One interesting comparison I plan to do will be the barlowed ES82 14mm vs the ES82 6.7mm.

Edited by AxelB, 10 February 2019 - 10:27 PM.


#5 Jond105

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Posted 10 February 2019 - 10:28 PM

I use both X-cels. 3x and 2x. Good quality. I used the ES82 8.8mm and 2x or the 14mm and 3x and got rid of the 4.7mm. For their price they are worth it. Although once I purchased another ED100 I did go back to buying another 4.7mm to get the most out of it.
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#6 M11Mike

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Posted 10 February 2019 - 11:19 PM

CN - FWIW I used a Celestron 2X Ultima with a 24/68 TV Panoptic with my SE8 and I did NOT experience any vignetting. 

 

M11Mike



#7 CollinofAlabama

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Posted 11 February 2019 - 12:52 AM

There's a thread on this topic here.  Read it all, especially the last bit.  For my money, the GSO 2.5x apo barlow is hard to beat.  It's not the cheapest, but it's proven itself against the TV 2x Barlow, and for less than half the cost, that's saying something.  BTW, the GSO 2.5x barlow actually functions as a 2.1x barlow, not a 2.5x one.  I've heard good things about the X-Cel LX barlows, but can't say from first hand experience.  Purchased the 3x model, but have yet to put it to the test.  But these are a little more expensive than the GSO 2.5, which is a little Spartan, for sure, and doesn't inspire confidence claiming to be a 2.5x barlow when it's really a 2.1x one, but I don't care about claims or beauty when I look through the eyepiece, I just want the view to be excellent, with color and detail in tact.  The GSO delivers where it counts.  The goofy marketing and looks come last.


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#8 CeleNoptic

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Posted 11 February 2019 - 01:15 AM

CN - FWIW I used a Celestron 2X Ultima with a 24/68 TV Panoptic with my SE8 and I did NOT experience any vignetting. 

 

M11Mike

 

Probably, depends on what version of the Ultima you have, there are long and shorty. If you used long one that might be a different story. I have a more popular shorty Ultima and it showed me *some* vignetting starting from a 14mm Meade 5K UWA and *obvious* vignetting with a 20mm ES68.



#9 NorthernlatAK

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Posted 11 February 2019 - 01:20 AM

There's a thread on this topic here. Read it all, especially the last bit. For my money, the GSO 2.5x apo barlow is hard to beat. It's not the cheapest, but it's proven itself against the TV 2x Barlow, and for less than half the cost, that's saying something. BTW, the GSO 2.5x barlow actually functions as a 2.1x barlow, not a 2.5x one. I've heard good things about the X-Cel LX barlows, but can't say from first hand experience. Purchased the 3x model, but have yet to put it to the test. But these are a little more expensive than the GSO 2.5, which is a little Spartan, for sure, and doesn't inspire confidence claiming to be a 2.5x barlow when it's really a 2.1x one, but I don't care about claims or beauty when I look through the eyepiece, I just want the view to be excellent, with color and detail in tact. The GSO delivers where it counts. The goofy marketing and looks come last.

Love this barlow. Got one new for 35$ from china but took awhile to get here. Waaay worth the price even though it is around 2.1× which is just fine by me.
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#10 penguinx64

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Posted 11 February 2019 - 07:37 AM

I had very good results with an Orion Tri-Mag 3x barlow in my Starblast 4.5 f4 reflector.  It works much better than the Shorty barlows I've tried.  But now, I have better eyepieces and I don't need to use a barlow with that scope.



#11 25585

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Posted 11 February 2019 - 08:04 AM

If you are planning ultra wide field eyepieces than a telecentric Barlow like 2x ES Focal Extender can be recommended. I have the Meade version of that and it's actually the only Barlow I use. Basically, the three element budget Barlows like Ultima work pretty good, but have serious limitations. I have a number of various Barlows and aware that telenegative Barlows especially shorties like Celestron Ultima vignetting long FL 82*AFOV (14mm+) and 68*AFOV (20mm+) eyepieces. In shorter FL UWA eyepieces telenegative Barlows increase spherical aberration (kidneybeaning). Telecentric extenders are free from those problems.

Consider a 2 inch Barlow, as you are considering 2 inch eyepieces. The ES recommended above comes jn either 2 or 1.25 inch sizes in 2x and 3x for each. The 2 inch are heavy.

 

Otherwise an Antares 1.6x or GSO 2x 2 inch are lighter.

.



#12 M11Mike

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Posted 11 February 2019 - 03:02 PM

CN - was the SHORT barlow - Celestron P/N 93506.  Made in Japan - 3 element - just UNDER 3" long.

 

M11Mike



#13 russell23

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Posted 11 February 2019 - 03:28 PM

The Orion Tri-mag gets excellent reviews here.  I have not tried that one but some rate it slightly above the 3x TV which I think is excellent.

 

I have tried the GSO 2.5x APO barlow (actually 2.1x) which I think is another excellent option. 


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#14 Astro-Master

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Posted 11 February 2019 - 07:48 PM

If your thinking for getting 2" eyepieces in the future, why not get a good used 2" TeleVue Big Barlow, you can use it on all your eyepieces.  Used they sell for around $100. its a good investment if your going to stick with the hobby



#15 CeleNoptic

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Posted 11 February 2019 - 08:30 PM

CN - was the SHORT barlow - Celestron P/N 93506.  Made in Japan - 3 element - just UNDER 3" long.

 

M11Mike

 

Well, same as mine, it means your mileage vary. smile.gif



#16 CeleNoptic

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Posted 11 February 2019 - 08:44 PM

The Orion Tri-mag gets excellent reviews here.  I have not tried that one but some rate it slightly above the 3x TV which I think is excellent.

 

I have tried the GSO 2.5x APO barlow (actually 2.1x) which I think is another excellent option. 

 Hi Dave,

 

IIRC you also said Siebert Barlows are excellent. What about Siebert telenegative or Siebert telecentric, how they compare to the 2.5x GSO?



#17 SteveG

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Posted 12 February 2019 - 04:54 PM

I just did a quick daylight test on the following, using a 100 ED refractor & 2" diagonal:

 

TV 3x Barlow

24 ES 68  No vignetting but a very bright orange ring at field stop

20 ES 68  No vignetting but same orange ring

22 Vixen LVW  No vignetting, just a hint of blue at the field stop

 

Orion TriMag 3x

24 ES 68  No vignetting, dim orange ring at field stop

20 ES 68  No vignetting, dim orange ring

22 Vixen LVW  No vignetting, clean field stop

 

Ultima Shorty 2x (actually about 2.2x)

24 ES 68  Considerable vignetting

20 ES 68  Considerable vignetting

22 Vixen LVW  No vignetting, hint of blue at the field stop

 

To the OP, your factory eyepieces will work well with any of these barlows, including the GSO. Your only issues would be trying to barlow a 1.25" 20-24 mm wide field type eyepiece.


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#18 Peter Besenbruch

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Posted 12 February 2019 - 10:21 PM

I heard good things of the 1.25" Orion Ultrascopic Barlow 2x. Any experience with it?

 

Is the Celestron X Cel Barlow also of good quality? Would the 3x be equally good?

I own the Celestron Ultima 2(.2)x, and the X-Cel LX 2x and 3x Barlows. The X-Cel 2x has replaced the Ultima, because it is a better Barlow. The fat tops of the X-Cels are hollow, and act as light traps. The X-Cels offer better light control than the Ultima. The X-Cels also vignette significantly less than the Ultima. I have used Televue (older models), Meade, and Baader Barlows. I like the X-Cels better.


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#19 JIMZ7

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Posted 12 February 2019 - 10:31 PM

Taiwan made 1.25" GSO 1.5x-2x. Agena sells it for $33 shipped. Nice to use it at 2x or 1.5x.

Jim


Edited by JIMZ7, 12 February 2019 - 10:31 PM.


#20 AxelB

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Posted 12 February 2019 - 10:40 PM

I did some critical on axis testing at crazy high power yesterday using the X-cel x2. 850x with my C8! Perfect text book collimation, clear Airy disk surrouded by diffraction rings. There was also two diffuse and very dim stars (or galaxies ?) in the same field of view. Sky Safari pro do not show these. Difficult to say what it was at such magnification snd tiny exit pupil.

Seeing was very good but I also had my custom fans running to keep up with the artic weather going down and break up tube currents.

I was not expecting such nice image at this ludicrous magnification. For sure the X-cel barlow works well to obtain crazy high magnifications. I still can’t believe I managed to do that from my location where seeing is rarely above average. Too bad Jupiter wasn’t in the sky!

Now the cons.

The single set screw pushes the ocular a bit on one side, this slightly moves the point of best collimation of my sct off center in the field of view but that’s almost négligeable. If only they could make one with a twistlock kind of centering mechanism that would be awesome. Still, this isn’t a show stopper. 15% offcenter at 850x with a 82 degree apparent field eyepiece is négligeable.

Edited by AxelB, 12 February 2019 - 10:50 PM.

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#21 CeleNoptic

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Posted 12 February 2019 - 11:50 PM

Taiwan made 1.25" GSO 1.5x-2x. Agena sells it for $33 shipped. Nice to use it at 2x or 1.5x.

Jim

 

I have tested it using a 'ruler approach' in my refractor. In its native extender this Barlow worked at 2.2x with most EPs tested (e.g. 25mm Ultrascopic, 20mm ES68, 11mm ES82) except a 12mm TV Delos (2.1x). Surprisingly, no vignetting. When the Barlow cell was screwed into the EP's filter thread it showed significant vignetting with the 25mm Ultrascopic and 20mm ES68 and worked either at 1.5x (6.5mm Meade HD-60, 20mm ES68, 12mm TV Delos, 11mm ES82) or at 1.7x (25mm Ultrascopic, 14mm Meade 5K UWA) so the magnification factor varies depending on the EP used.


Edited by CeleNoptic, 12 February 2019 - 11:55 PM.


#22 barbie

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Posted 13 February 2019 - 12:16 AM

I have the Highpoint Scientific 2x barlows which are made in Taiwan and is of excellent quality and quite affordable. I think it's around $45.00.  I've used them at very high mags on the planets in my 4"F9 apo and in my former 6"F8 Newtonian and they performed extremely well.



#23 russell23

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Posted 13 February 2019 - 12:07 PM

 Hi Dave,

 

IIRC you also said Siebert Barlows are excellent. What about Siebert telenegative or Siebert telecentric, how they compare to the 2.5x GSO?

I never directly compared a Seibert to the GSO.  But I did compare the 2.5x Seibert Telecentric to the 2.5x Powermate and found the Seibert to be clearer, sharper, and easier to pull out fine lunar details.  

 

The Seibert barlows and telecentrics are excellent if you don’t mind the price and the wait time.  I also recommend the self centering mechanism even though it adds to the cost.


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#24 N3p

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Posted 13 February 2019 - 12:39 PM

I would not take a 3x Barlow, I think 2x is already more then enough with a 1200mm Newtonian.

 

There might be a urge to fill the 200x to 500x range of powers, but frankly at the beginning, I would put the money into anything lower then 250x. 150x to 250x for planetary/moon and bellow 150x for the rest.



#25 CollinofAlabama

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Posted 13 February 2019 - 01:26 PM

I purchased the Celestron X-Cel LX 3x barlow to give it a try.  I wouldn't argue with your point, N3p, that this is often too much power.  For my 10mm BCO, I tend to agree with your assessment.  It's rare in my skies, that they'd support a 3.33mm-simulated eyepiece in most of my scopes.  Possible, especially on a target like the moon, but for most things, even double stars that require a steadiness in atmospheric cooperation, rare, indeed.  However, with a 3x barlow, eyepieces like my 20mm or 17mm Long Perng Plossls, or an 18mm BCO (which I might pick up to check out), begin to have planetary implications they otherwise would not possess.  The 3x barlow opens up that realm in the medium to low power eyepieces.  One must be careful with this.  Barlows tend to increase eye relief, and with something like a 25mm plossl, the eye relief can render the eyepiece-with-barlow prone to blackouts.  But in the 20mm and below sizes, they can become planetary contenders that they otherwise wouldn't really be.  9mm is good, but 6mm is planetary, and, of course, 18mm is not, so a 3x barlow can have a place in the eyepiece case.  And it's always there should the Sky Godesses unveil their heavenly bodies and allow sub 5mm-equivalent-barlow-combos to reveal their celestial glories.  Always ready.  The 3x barlow, kind of like a condom.


Edited by CollinofAlabama, 13 February 2019 - 01:29 PM.

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