SvBony F9125A Barlow

[Zeta Reticulan]

 

I’ve been experimenting with the stand-alone SvBony ‘F9125A’ element. This Barlow element magnifies by about 1.6x when threaded directly into an eyepiece.

Which I assume it was originally designed to do.

It is lightweight, well baffled, and with filter threads that are compatible with everything that I’ve tried in it. SvBony claim that the element has a diffraction coating. It may be an achromatic doublet although the only information I can glean from the SvBony site is that it is constructed from a 'pure optical glass lens'. In use it has a high transmission with very good acuity and colour separation.

It dawned on me that it might be a good replacement for a standard Barlow element. So I swapped the stock element threaded into my SvBony T-thread, which has a standard twenty two millimetre barrel. The F9125A is lighter than the stock T-thread element and has the advantage of a filter thread. SvBony claim it weighs twelve grams with a height of twenty two millimetres and a fine thread M28.5*0.6 pitch interface.

First impressions with this as a conventional Barlow were promising. I easily split all three elements of Alkalurops with a 60mm doublet. It was as effective on other doubles. Lunar and planetary observations were equally satisfying. Whilst viewing Saturn with my Sky-Watcher 80ED Evostar I did get occasional hints of false colour as Saturn approached the eyepiece field stop. This rapidly disappeared as I moved more on-axis. So I’m not totally sure what was causing this. I was using a 7.5mm Takahashi LE eyepiece for 160x.  Atmospheric problems with Saturn being at a fairly low altitude may have been the culprit.

The overall images produced with this hybrid Barlow were incredibly good, even when directly compared with my 2x Tele Vue Barlow. In fact, the F9125A displayed a brighter image, although I perceived the Tele Vue to have very slightly more contrast. Both Barlows displayed equally sharp images.

I’m quite impressed with the F9125A, it’s definitely a keeper.