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Gso and svbony 2X barlows

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#1 Hamlet

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Posted 26 June 2019 - 08:33 PM

The gso and the svbony are in the same quality?, the svbony is a bit more cheap, but if are both the same should I go for the svbony?

Svbony barlow:

https://www.ebay.com...redirect=mobile

Gso barlow:

https://www.ebay.com...redirect=mobile



#2 MartinPond

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Posted 26 June 2019 - 09:19 PM

The SVBONY I tried had a 1-piece lens coated on one side only.

It was surprisingly good, even for chromatics, but the contrast was not up to par

 with the moderate shorty EPs from Meade or Orion, etc (or GSO)... 

 

I got it for $9 , so it made a great extension tube with filter threads..without the optics.


Edited by MartinPond, 26 June 2019 - 09:20 PM.


#3 Hamlet

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Posted 26 June 2019 - 10:35 PM

Have you try it the gso one? Should I purchase the gso instead the svbony?



#4 epee

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Posted 27 June 2019 - 09:38 AM

I trust GSO more than Svbony. Also note that the GSO says that it is "fully multi-coated", while the Svbony only says, "in the original package".

 

You can get the same GSO at Agena Astroproducts for $2 more but with shipping included: https://agenaastro.c...-extenders.html

 

You can also get the house brand from this site's sponser for $30, and likely get the 10% Cloudy Nights' discount: https://www.astronom...-eyepieces.html


Edited by epee, 27 June 2019 - 09:43 AM.


#5 Ihtegla Sar

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Posted 27 June 2019 - 10:02 AM

If you are willing to spend another twenty dollars, the 2.5x GSO (which actually only gives 2.1x magnification) is a big step up in quality from either the 2x GSO or the Svbony.

https://agenaastro.c...arlow-lens.html

Edited by Ihtegla Sar, 27 June 2019 - 10:03 AM.


#6 Hamlet

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Posted 27 June 2019 - 10:41 AM

That one seems to be a better choice

 

Update: I found this pack on ebay , includes the barlow and a diagonal https://www.ebay.com...redirect=mobile


Edited by Hamlet, 27 June 2019 - 10:48 AM.


#7 Ihtegla Sar

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Posted 27 June 2019 - 11:05 AM

I don't know the quality of that diagonal but at that price you are basically getting it for free.  I do have the 2.5x GSO Barlow and can vouch for it being very good.  It feels like a quality device and gives good images, and is frequently recommended here as being a very good Barlow for the price. 

 

I also recently purchased the 2.0x Svbony Barlow but haven't had a chance to use it yet, but just looking at it it is obviously not the quality of the 2.5x GSO and my 2.0x Svbony came with somewhat dirty optics.  I bought the 2.0 Svbony to make a dedicated Barlowed laser for collimating my dob, so I wasn't worried too much about its quality.  I plan to try it out visually first  but we have had nothing but clouds the past couple weeks so I haven't been able to look through it.  But the Svbony definitely looks and feels like an inexpensive budget device, whereas the GSO 2.5x has the look and feel of a quality in addition to putting out nice views.



#8 Hamlet

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Posted 27 June 2019 - 11:20 AM

This quote: "From my experience, telenegative *shorty* Barlows seem to increase spherical aberration in eye pupil especially in shorter FL Wide Angle eyepieces which already have that type of aberration like ES82s/Meade 5K UWAs. When I tried my 8.8 Meade 5K UWA with the 1.25" 2x GSO Barlow I was struggling finding proper eye position. That's why I exclusively use 2x Meade TeleXtender. And it also helps with barlowing longer FL Wide Angle EPs -- no vignetting."  is from this topic: https://www.cloudyni...25x-apo-barlow/

A shorter barlow could gives more CA to the f5 80mm meade? Ahh...this is so confuse to meconfused1.gif confused1.gif 



#9 dgordontx

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Posted 27 June 2019 - 11:48 AM

I have not tried the GSO but I do own the SVBONY and am very pleased with it. I put it on my 5.5mm EP the other day bringing me to 553x mag and Jupiter was brilliant. I lost probably 10% clarity but the double mag made up for it.

 

A few things to note is that I have never tried any other barlow and have no comparison for quality. Also, Jupiter was near transit at this point.



#10 Ihtegla Sar

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Posted 27 June 2019 - 11:59 AM

This quote: "From my experience, telenegative *shorty* Barlows seem to increase spherical aberration in eye pupil especially in shorter FL Wide Angle eyepieces which already have that type of aberration like ES82s/Meade 5K UWAs. When I tried my 8.8 Meade 5K UWA with the 1.25" 2x GSO Barlow I was struggling finding proper eye position. That's why I exclusively use 2x Meade TeleXtender. And it also helps with barlowing longer FL Wide Angle EPs -- no vignetting."  is from this topic: https://www.cloudyni...25x-apo-barlow/

A shorter barlow could gives more CA to the f5 80mm meade? Ahh...this is so confuse to meconfused1.gif confused1.gif 

I am admittingly not an expert but that comment does not make a lot of sense to me, and there was no other discussion in the thread about a Barlow increasing spherical aberration using a shorter wide field eyepiece.  A Barlow is supposed to reduce the effective focal length of an eyepiece, which would in theory reduce the aberrations inherent in the eyepiece, or so I have read. 

 

It sounds like that guy is advocating focal extenders rather than Barlows.  A focal extender is like a Barlow but works slightly differently and are typically more expensive.  See this thread for a discussion of the differences.  One of the differences is that a focal extender does not affect eye relief and a Barlow increases eye relief, which I find to be a good thing but some people have trouble with eye placement if there is too much eye relief and I suspect that was what the commenter was talking about with his complaint about eye position.

 

AS far as his comments about spherical aberration, I have used the 2.5 Barlow in my 100mm f/9 apo refractor with the ES 6.7, 8.8 and 11mm 82 degree eyepieces on Saturn and Jupiter and have not noticed any spherical aberration.  It gave very clear images.  But my telescope has no spherical or chromatic aberration.  

 

If you have an f/5 refractor that has chromatic aberration, than any increase in magnification is going to exacerbate that, whether it is a Barlow or a focal extender or just a shorter focal length eyepiece that you are using to increase magnification.  



#11 Hamlet

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Posted 27 June 2019 - 12:56 PM

Mm...I really need some advices from people who owns the meade or the OriĆ³n. I have read some reviews from this forum and others But everyone who has write on that threads have the knowledge on what they are talking, and....I have like zero knowledge on that, and maybe it's really easy to buy eyepieces or barlows or anything that will not work.

 

I feel lost ....

 

But i really apreciate you'r advices and the efforts smile.gif, thanks to all!



#12 Peter Besenbruch

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Posted 27 June 2019 - 05:04 PM

This quote: "From my experience, telenegative *shorty* Barlows seem to increase spherical aberration in eye pupil especially in shorter FL Wide Angle eyepieces which already have that type of aberration like ES82s/Meade 5K UWAs. When I tried my 8.8 Meade 5K UWA with the 1.25" 2x GSO Barlow I was struggling finding proper eye position.

Short, standard Barlows should have 3 elements for best performance.


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#13 Hamlet

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Posted 27 June 2019 - 06:23 PM

Then the GSO 2.5X it's fine!




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