If you need more power than your eyepieces alone can provide, we offer a new apochromatic 5x Barlow lens from GSO (Guan Sheng Optical) to give a big magnification boost to any 1.25" eyepiece it's used with.
Nothing has been compromised in GSO's latest and finest offering. This Barlow features an air-spaced, three-element, apo design with fully multicoated optics. The housing is precision machined from aluminum stock and black anodized to a hard finish. The lens edges and inner barrel are blackened to provide maximum contrast. The Barlow body includes a safety undercut on the lower barrel and a brass compression ring so that your eyepiece barrels are not marred by the captive set screw. The 5x model has a clear aperture of 13mm, but it is not threaded to accept 1.25" filters.
For those blessed with great optics and dark skies, the 5x could be an exciting new addition to your arsenal for visual and photographic use. If you've never used such a powerful barlow before, please be aware that to get the best out of this barlow, you need to use it with a good telescope, a good eyepiece and under good seeing conditions. See more on this topic below.
- Barrel size = 1.25" (31.7mm)
- Magnification factor = 5x
- Weight = 3.8oz (108gm)
- Total height = 3.46" (88mm)
- End caps = 2
- 1.25" filter threads on bottom of barlow: No
- Made in Taiwan
Please note: This is a very high magnification barlow. It is not for everyone or for common viewing conditions. Before buying, please make sure that you are using realistic magnifications with your telescope. A good rule of thumb is that under very good conditions and with a very good telescope, the maximum power you will be able to use is about 50x of magnification per inch of telescope aperture. With average telescopes and/or average conditions, you should be able to use 30x of magnification per inch of telescope aperture. So for example, if you have a 6" telescope, under typical conditions you will be limited to 6x30 = 180x of magnification, and 6x50 = 300x of magnification at best.
Boosting the magnification beyond this recommended maximum for your telescope aperture is not realistic. This is bound to result in image break-down, causing fuzzy images, focusing difficulties, increased color around objects (caused by other optical elements in the telescope which are magnified by the barlow) and general disappointment, but this is not a fault of the barlow.
May 6, 2018
good price vs performacePros: Cons: Comments:
overall its good for the money. i have used it with my 8" Newtonian for planets. yet to try it for planetary AP. i also have the GSO ED 3X Barlow and it performs better than this in same magnification.
This review was provided courtesy of AgenaAstro.comJun 13, 2014
Wow So ClosePros:
Compact,Easy to Use,Strong ConstructionCons:
Difficult To FocusComments:
On my CPC 800 I find the use of the GSO 1.25" 5x Apochromatic Barlow Lens very hard to focus. Don't get me wrong, it's still good for getting close to things if you are just looking. Maybe its my lenses because there not so great, still on the cheap ones.
This review was provided courtesy of AgenaAstro.comMay 30, 2013
Great quality, but a niche productPros:
Easy to Use,Strong Construction,CompactCons:
Difficult To FocusComments:
I purchased this barlow to use with a webcam CCD in my 10" f/4.7 scope for planetary imaging. With the 5x barlow it bumps the scope up to f/24, which is closer to where I need to be for planetary imaging with a CCD.
The complexities of aiming, aligning, and focusing a 10" f/24 scope aside, I found that this barlow did very well. Once focused, the image stayed sharp across the field and had even illumination.
However, I was a bit disappointed by the chromatic performance. While billed as an apochromatic barlow, I found that there was noticeable blue fringing around bright targets. All other colors, however, were kept well in check.
This barlow also has a problem with dust motes. Due to the high power of the lens, your camera comes to focus with the barlow's objective lens a hair's width below the primary mirror's focal plane. The result is that any foreign material on the barlow's objective lens is visible in your CCD image. Great care must be taken to have pristine lens surfaces to prevent this effect.
In all, I am happy with my purchase. But for those interested in it, do keep in mind that this barlow packs a LOT of power, and will very easily overpower your scope if used visually. It will be basically unusable in an f/10 SCT for both visual and camera work, as it will magnify well beyond the diffraction limit of the scope. It's best used in fast (f/4-f/6) scopes to "convert" them into slower scopes for planetary imaging.
This review was provided courtesy of AgenaAstro.comApr 30, 2012
Strong Construction,Accurate,Quality LensesCons:
Difficult To FocusComments:
Very good item but difficult use about his magnification (x5), I only can use with a very good weather conditions.
This review was provided courtesy of AgenaAstro.comOct 28, 2011
Not as good as I thoughtPros: Cons:
Poor Lens Quality,Difficult To FocusComments:
Meh... So far I could not get a good impression of it. Difficult to focus, the lens quality does not seems very good, the field looks much more dark than with my Powermate 2.5X.
This review was provided courtesy of AgenaAstro.com
- Skill Level
- Time with Product
Jun 6, 2011
- User Notes:
- Review by Sebastian of Buenos Aires, Argentina.
Does its jobPros:
Strong Construction,AccurateCons: Comments:
At first, I received a defective unit, but guys from Agena replaced it and it works like a charm now.
Granted, this is not a Powermate, but it does its job. I couldn't see any noticeable chromatic aberration and it worked great while coupled with several different eyepieces.
I'd definitely buy it again.
This review was provided courtesy of AgenaAstro.comDec 19, 2010
Great barlow for a great pricePros:
Strong Construction,Quality Lenses,AccurateCons: Comments:
I use this all the time as a planetary webcam magnifier, and for collimating my SCT, which has a short [1600mm] focal length, so I need a lot of help getting the high power needed for collimating ,while still using a lens that's bright enough to still make the star stand out. With this barlow I have no problems getting the concentric rings to show up enough for accurate work.
This review was provided courtesy of AgenaAstro.comMay 17, 2010
Good value for moneyPros:
Accurate,Quality Lenses,Strong Construction,CompactCons: Comments:
The Barlow 5x is a great tool for my short focal distance reflector telescope, which allows me to get better views of planets...
This review was provided courtesy of AgenaAstro.comMay 7, 2010
Quality Lenses,Excellent finish,Accurate,Strong Construction,CompactCons: Comments:
I purchased this to use for planetary video and when seeing is good it is excellent. Also use it on my SV80S and it works great with very sharp images. The quality is excellent, which I find unusual today.
This review was provided courtesy of AgenaAstro.comMay 27, 2009
I would buy this product againPros:
Strong Construction,Quality Lenses,AccurateCons:
Difficult To FocusComments:
The quality of this product is really good if you got to think about the price. I am using it to take pictures of the planets via webcam. That the focusing is not really easy is absolutely normal if you know that the optical chip in a webcam is very small. The TeleVue`s Powermate will be always better, but you got to pay four times more than this. I would buy it again!
This review was provided courtesy of AgenaAstro.comFeb 19, 2009
An excellent buy at an affordable price!Pros:
Strong Construction,Compact,Quality Lenses,AccurateCons: Comments:
I bought this barlow shortly before the opposition of Mars in December of '07. The views through my 10" reflector were surprisingly crisp, even though I surpassed the power rule of 50x per inch of aperature. Another great feature is the fact that it uses a compression ring which gives uniform snugness as compared to a setscrew which tends to mar the collar of the eyepiece. All in all a great buy. Thanks guys.
This review was provided courtesy of AgenaAstro.comSort by