SvBony SV137 2x Barlow

Discuss telescope eyepieces.
Post Reply
User avatar
Shorty Barlow
Interdicted
Articles: 0
Offline
Posts: 267
Joined: Thu Jan 30, 2020 1:25 am
4
Status:
Offline

SvBony SV137 2x Barlow

#1

Post by Shorty Barlow »


I was pretty impressed with the SvBony 3x Barlow, considering its competitive retail price. This made me wonder about the 2x version of the same bargain basement model. So, for a grand total of £19.99p I ordered one.

Image

My first impression of the Barlow, after taking it out of the box, was that it felt like it could have come out of a Christmas cracker. It’s not heavy, lighter (barely 55 grams) in fact than its GSO equivalent, which is mostly made of aluminium. The SvBony has a chromed-brass barrel. The housing is very shiny, both outside and inside, which is not ideal.

Image

I was pretty convinced for a while that this is constructed from a lightweight polymer rather than a form of alloy. I don’t know. Kryptonite perhaps? It is very shiny. I now think it is light cast aluminium.

SvBony’s marketing department claim:

“Cemented doublet and FMC film enhanced light transmission and achromatism; Unique matting ink around the glass lens decrease the stray light” (sic)

So I’m guessing the element edges have been blacked. The barrel is conventionally baffled, the element has no provision for a filter thread. From my measurements this ‘shorty’ Barlow is 75mm tall with a standard 22mm brass barrel. The element stands 16mm tall in its housing with at least 20mm of clear aperture.

Image

Like its taller 3x sibling, the element is coated, although not obviously. I’ve read erroneous reports that these Barlows are uncoated. This is patently untrue as even a cursory glance reveals a pale green hint of optical coating. It’s probably fairly basic notwithstanding claims of ‘fully multi coated’. Although it doesn’t appear detrimental or affect its efficacy in use.

Image

It features a brass compression ring and a plain brass screw. The screw isn’t the smoothest I’ve used but it held a Celestron zoom pretty securely. I certainly didn’t have any anxieties about it working loose. Many short Barlows have very small, almost undersized fastening screws.

Image

I don’t always trust heavier eyepieces with these.

Image

I directly compared the SV137 with a stock 2x GSO short Barlow that has only a slightly more expensive retail price. The GSO is basically a bog-standard two element Barlow. The comparison was on various double stars that could be viewed with my modified ST80 and a Celestron zoom giving magnifications between 33.3x and 100x. The seeing was below average. I honestly couldn’t see any discernible difference between the two Barlows. They both gave sharp, bright images, without any excess false colour or aberrations that I could see (I expect a certain amount of natural CA with the ST80). The ‘Christmas cracker’ SvBony should be at least as good as the GSO on most targets. The element is fairly well constructed but the housing has its issues in my opinion. It isn’t internally blackened, which possibly explains its competitive retail price. Optically I could perceive no difference to the similarly priced GSO unit.

Image
User avatar
The Wave Catcher United States of America
Jupiter Ambassador
Articles: 0
Offline
Posts: 210
Joined: Fri Oct 09, 2020 8:59 pm
3
Location: Fort Worth, Texas, U.S.A.
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: SvBony SV137 2x Barlow

#2

Post by The Wave Catcher »


I just received my SvBONY SV137 3x Barlow today. It's too cold and cloudy to test it out yet but for the price I thought I'd get it to play with. If it is any good, it'll allow me to have close-up views of the planets with my 82-degree wide, Stellavue, 15 mm eyepiece, I hope. Now that it's been a few months I wonder if you have any more comments about it.

Thanks.
Steve Yates

Astro-Tech AT102ED, 102 mm, F/7, ED Achromatic Refractor
Astro-Tech AT80ED, 80 mm, F/7, ED Achromatic Refractor
Bresser AR102s, 102 mm, f/4.5, Achromatic Refractor

Explore Scientific Twilight I Alt/Az Mount
Bresser Nano Alt/Az Mount
Post Reply

Create an account or sign in to join the discussion

You need to be a member in order to post a reply

Create an account

Not a member? register to join our community
Members can start their own topics & subscribe to topics
It’s free and only takes a minute

Register

Sign in

Return to “Eyepieces”