SvBony F9125A Barlow Element

[Nightspore]

 

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

 

SvBony (sic)

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.  

 

 

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

 

 

It was delivered with its own plastic carrying container. My first impression was that it was quite lightweight compared to the one I’d separated from its Barlow. It was well baffled and I was pleased to discover its filter threads are compatible with every filter I’ve threaded into it. The lens surface at the interface shows a strong curvature which made me wonder if it actually would magnify by 2x when threaded directly into an eyepiece barrel. It doesn’t. It is coated as you can get a hint of the green coating when it is held up to a light source.

 

 

SvBony claim it has a ‘broadband’ coating. 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. Shown below threaded into an old 'Celestron' T-thread Barlow. These T-thread Barlows have been on the market for a long time and more recent versions feature aluminium barrels rather than the 22mm chromed brass one on mine. They are also marketed by Sky-Watcher, Vixen and SvBony, among others. I believe they were originally manufactured by Barsta.

 

 

The actual magnification will depend on the barrel length (distance from the field lens). I have a feeling that most standard 22mm barrels would give a 2x magnification. In use, when threaded into a 6mm Vixen SLV, it delivers a bright image and appears to have excellent transmission. I saw no degradation in colour separation or acuity at about 90x viewing several double stars, Saturn and Jupiter. It’s certainly lighter than carrying a 4mm SLV as well as a 6mm. 

 

 

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

 

(from SvBony’s webpage)
 

Edited July 4, 2022 by Nightspore