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SvBony F9125A Barlow Element

Discussion in 'Eyepieces, Barlows, and Filters' started by Mak the Night, Jul 5, 2022.

SvBony F9125A Barlow Element

Started by Mak the Night on Jul 5, 2022 at 1:22 PM

16 Replies 791 Views 3 Likes

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  1. Mak the Night

    Mak the Night Well-Known Member

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    SVBONY 1.25'' 2X Barlow Lens Telescope M28.5*0.6 Thread for Standard Monocular Optics Compact Eyepiece 31.7mm SvBony (sic)

    [​IMG]

    I thought I was being pretty clever using a stand-alone 2x SvBony Barlow element to decrease the focal length of my 6mm Vixen SLV. The element itself was threaded from off my rather shiny silver coloured SvBony 2x Barlow housing.

    [​IMG]

    Imagine my surprise when I discovered that SvBony actually market separate individual 2x Barlow elements. I thought £13.99 (GBP) was reasonable and duly acquired one.

    [​IMG]

    It was delivered with its own plastic carrying container. My first impression was that it was quite lightweight compared to the SvBony element that I’d initially separated from its respective housing. The stand-alone element was well baffled and I was pleased to discover that its filter threads were compatible with everything I threaded into it. The lens surface at the field lens interface shows a strong curvature. This made me wonder if the element actually would magnify by 2x when threaded directly into an eyepiece barrel. It doesn’t, as I suspected. It is definitely coated though as you get a hint of a green surface sheen when the glass is held up to a light source. SvBony claim it has a ‘broadband’ coating.

    [​IMG]

    After several daylight comparison tests I’d estimate it gives about 1.5x when threaded directly into an eyepiece barrel. However, it will also thread directly into most Barlow housings where it will probably increase the magnification to around 2x. This element is shown below threaded into an old 'Celestron' T-thread Barlow originally from a kit. These generic T-thread Barlows have been on the market for a long time and more recent versions feature aluminium barrels (often with an undercut) rather than the 22mm chromed-brass one on mine. They are also marketed by Sky-Watcher, Vixen, and and even SvBony. I believe they were originally manufactured by Barsta (BST).

    [​IMG]

    The actual magnification will depend on the barrel length (potential distance from the field lens).

    [​IMG]

    I have a feeling that most standard 22mm Barlow barrels would give a 2x magnification. However, this would be slightly greater in the 30mm barrel typically used in many GSO Barlows (above left). When threaded directly into a 6mm Vixen SLV the F9125A delivers a bright image and appears to have excellent transmission. I saw no degradation in colour separation or acuity (at an assumed 90x) when viewing several double stars and the planetary targets Saturn and Jupiter.

    [​IMG]

    Specification:
    1, Brand: SVBONY
    2, Barrel Size: 1.25" (31.7mm)
    3, Magnification Factor: 2X
    4, Lens material: pure optical glass lens
    5, Sleeve material: Metal
    6, Lens coating: Broadband coating
    7, Thread interface: M28.5*0.6 pitch (Fine Thread)
    8, Weight: 12g
    9, Total Height: 22mm

    (SvBony’s webpage)
     
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  2. Orion25

    Orion25 Well-Known Member

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    Lovely selection!
     
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  3. Ed D

    Ed D Well-Known Member

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    Interesting information. I routinely use Barlow elements (GSO, Tele Vue, William Optics) for imaging and observing, especially when I want just a little boost. I have also used the Barlows with extension tubes to increase magnification. Another plus to extending the lens to eyepiece/camera is that the longer distance does help to reduce chromatic aberration. (Think f/5 vs f/20 achromats)

    Thanks for the post! It's good to know the individual Barlow elements are available.

    Ed
     
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  4. Mak the Night

    Mak the Night Well-Known Member

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    Thanks Ed, and you're welcome. Using an element can be a convenient way of minimising overall weight with a light grab and go set-up. I've recently been going out with just two eyepieces and a TV 2x Barlow. It's quite liberating in many ways. Unfortunately TV threads aren't particularly compatible with other eyepieces.

    baader.jpg

    I use this Baader Hyperion Barlow a lot with the 6mm Vixen SLV. It gives 135x in the Altair 60 EDF which is quite useful for splitting some doubles.
     
  5. Nebula

    Nebula Well-Known Member

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    How is the Svbonny barlow compared to something else like very expensive balow lens. Is it a godd competitor?
     
  6. Mak the Night

    Mak the Night Well-Known Member

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    It compares well with most other achromatic Barlows. It might be only fourteen quid, but bear in mind that's just for the element and housing.
     
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  7. Nebula

    Nebula Well-Known Member

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    @Mak the Night your picture from post #6, this is the Baader Hyperion Zoom 2.25x barlow right? Personnaly i am attracted to the idea of a 1.5x barlow as your tests with the 6mm even 1.25 would be nice.
     
    Last edited by a moderator: Aug 5, 2022 at 1:31 AM
  8. Mak the Night

    Mak the Night Well-Known Member

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    Last edited by a moderator: Aug 5, 2022 at 1:32 AM
  9. Nebula

    Nebula Well-Known Member

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    Ahh a 1.5 barlow! Made in Canada. !

    Looks like nice number 1.5.
     
  10. Mak the Night

    Mak the Night Well-Known Member

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    It's solidly built but the filter threads are too big, which was a problem with some Antares reducers as well. My main problem with it is it's too heavy. The element is pretty good though.
     
  11. Nebula

    Nebula Well-Known Member

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    Ok ok too heavy a bit, if you don't like it, you don't like it.

    Threads are very variable here, some of my filters are smooth with some eyepieces and not with others. As if everything is in fact, partially compatible with everything only.
     
  12. Mak the Night

    Mak the Night Well-Known Member

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    It's not that I don't like it, it's just that it's built like a tank lol. The F9125A is still performing well. At 90x with the 60 EDF I could see all three stars of Iota Cass and Mu Bootis. I could see several moons of Saturn and some detail on Jupiter.
     
  13. Nebula

    Nebula Well-Known Member

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    hey thanks for the suggestion Mak, I will try Iota Cass during my next observation, I have difficulties splitting tight doubles with my Newtonian, it would be caused by the fact that I don't know how to collimate, according to the friendly people of CN.

    But I want to try Iota Cass anyway, at 90x. Mu has a separation of 0.7" I never had success even once with anything that close.

    You sure have good success with your barlow.
     
  14. Mak the Night

    Mak the Night Well-Known Member

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    I've never had much success with tight doubles with a reflecting scope. Mak's are particularly bad because of the bright first diffraction ring. Anything with an obstruction can thwart attempts to split close doubles. It might be a collimation issue, but I doubt it. I ceased paying any attention to anyone on CN years ago. In fact, I don't use the forum now. I remember people on CN telling me I would have no chance of seeing M57 with an ST80. I can see it with a 60mm refractor! Mu Bootis needs above average conditions usually, and a bit of concentration. I should imagine it was do-able with a 200mm Newtonian though. I find that too much magnification can be detrimental.
     
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  15. Mak the Night

    Mak the Night Well-Known Member

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    I got carried away and made a Barlow kit with the F9125A replacing the original SvBony element.

    carried away.jpg

    The eyepieces now have brass barrels and are a 10mm SvBony aspheric and a 7.5mm (Barsta) Plossl. The end caps to the left of the Barlow contain a Lumicon #11 filter.
     
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  16. Nebula

    Nebula Well-Known Member

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    @Mak the Night
    I've never had much success with tight doubles with a reflecting scope. Mak's are particularly bad because of the bright first diffraction ring. Anything with an obstruction can thwart attempts to split close doubles. It might be a collimation issue, but I doubt it. I ceased paying any attention to anyone on CN years ago. In fact, I don't use the forum now. I remember people on CN telling me I would have no chance of seeing M57 with an ST80. I can see it with a 60mm refractor! Mu Bootis needs above average conditions usually, and a bit of concentration. I should imagine it was do-able with a 200mm Newtonian though. I find that too much magnification can be detrimental.

    That's what I think too, the obstruction and maybe the spiders too. M57 must be easy with a ST80... a bad opinion/advice again.. Pretty sure I saw it with my 8x45 binoculars.

    I didn't tried Mu Bootis tonight, the program changed and it was a planetary observation instead.. bootes was not accessible also from my position. To be retried at a later date

    Cool little portable kit of 2 eyepieces, 1 barlow and 1 filter. Only the imagination is the limit for creating new portable combinations.

    From memory the #11 is Yellow-Green, very good for Saturn, that was a suggestion from you.
     
  17. Mak the Night

    Mak the Night Well-Known Member

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    Yeah, I'm pretty sure you can see the Ring Nebula with binoculars. Bootes was mainly in the west for me. I still got Izar and Alchopops lol.

    That kit keeps changing ...

    Saturn's very bright at the moment. I like yellow and yellow green for Saturn. Saturn doesn't respond to most filters, not sure why.
     

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