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same SVBONY 3-8MM clickzoom eyepieces have different focal points in binos

Eyepieces
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#1 .mike

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Posted 05 February 2024 - 02:37 AM

Just wanted to give everyone a heads up that the SVBONY 3-8MM zoom eyepieces don't have the same focus (focal point?) between the same model eyepieces.  Last year for black Friday, I bought 2 of these zoom eyepieces from aliexpress to use in my bino's.  With both eyepieces in, one of them is not in focus while the other one is.  I have to manually raise one of them to be in focus.  I messaged SVBONY a few times and they never got back to me.  This is the first set of eyepieces I ever came across that had this issue.

 

gear I used was Televue NP101, Televue binoviewers, and various sets of eyepieces prior to the SVBONY's, never had a single issue.

 

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#2 .mike

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Posted 05 February 2024 - 02:40 AM

I had to pull out the "faulty" eyepiece in order to get focus

 

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#3 .mike

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Posted 05 February 2024 - 02:41 AM

Has anyone else had any of these sorts of issues with binos and SVBONY eyepieces?

 

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#4 Avgvstvs

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Posted 05 February 2024 - 02:59 AM

I have had a few SVBony issues like lenses falling out of their zoom Eyepiece. You get what you pay for. No its not Televue or Pentax. The price reflects this. Hope you can get your money back.


Edited by Avgvstvs, 05 February 2024 - 03:05 AM.

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#5 RAKing

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Posted 05 February 2024 - 09:22 AM

Zooms work by moving lenses back and forth.  It sounds like their design and/or manufacturing tolerances are a little looser than you expected.  SVBONY might not have expected BV use with multiple eyepieces.  Good luck!


Edited by RAKing, 05 February 2024 - 09:24 AM.


#6 Dave Novoselsky

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Posted 05 February 2024 - 09:26 AM

It’s not a Nagler zoom, but also it’s not priced like one either.  You do get what you pay for but also if it still functions albeit with the need for some adjustment in use is it worth buying?  Classic conundrum ain’t it.


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#7 Souldrop

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Posted 05 February 2024 - 10:34 AM

I had the same issue. Sent them back via amazon. 



#8 denis0007dl

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Posted 05 February 2024 - 11:48 AM

Hey hey guys, thats not eyepieces fault!

 

Its about binoviewer!

 

Max deepth point where eyepiece sit down inside each eyepiece holder, is NOT same on each side!!!

 

Thing is Svbony eyepeices have way to long 1.25" barell for most binoviewers, so what you need to do, lock both epcs in paralell position- problem SOLVED!!!

 

Denis


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#9 Victor Martinez

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Posted 05 February 2024 - 12:12 PM

Denis, can you clarify that a little?

#10 .mike

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Posted 05 February 2024 - 12:53 PM

Hey hey guys, thats not eyepieces fault!

 

Its about binoviewer!

 

Max deepth point where eyepiece sit down inside each eyepiece holder, is NOT same on each side!!!

 

Thing is Svbony eyepeices have way to long 1.25" barell for most binoviewers, so what you need to do, lock both epcs in paralell position- problem SOLVED!!!

 

Denis

the Svbony eyepieces fit all the way into the barrel of the televue bino's - if you are referring to the photo where they are not even, its because I had to manually raise one eyepiece and lock it in higher
 


Edited by .mike, 05 February 2024 - 12:53 PM.


#11 Eddgie

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Posted 05 February 2024 - 03:03 PM

I have posted on this elsewhere several months ago.

 

As others have said, it is not the binoviewer or the eyepieces, it is the combination of the two. 

 

These eyepieces have a relatively long barrel, and if your diopter is too low on one side or the other or both) you can run out of inward travel as the end of the eyepiece barrel contacts the limit ring in the bino that keeps the end of the barrel from hitting the prism.

 

The solution is to use parfocalizing rings or start with both diopters all the way up/out, focus with the eye that need the most outward travel, then shorten the opposite diopter.

 

I chose to go with the parfocalizing rings myself as they were dirt cheap on Amazon. Now I can move my MB II diopters though the full range without problem.

 

Screenshot 2024-02-05 140145.png

 

https://www.amazon.c...e?ie=UTF8&psc=1


Edited by Eddgie, 05 February 2024 - 03:06 PM.

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#12 kroum

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Posted 05 February 2024 - 03:12 PM

I have posted on this elsewhere several months ago.

 

As others have said, it is not the binoviewer or the eyepieces, it is the combination of the two. 

 

These eyepieces have a relatively long barrel, and if your diopter is too low on one side or the other or both) you can run out of inward travel as the end of the eyepiece barrel contacts the limit ring in the bino that keeps the end of the barrel from hitting the prism.

 

The solution is to use parfocalizing rings or start with both diopters all the way up/out, focus with the eye that need the most outward travel, then shorten the opposite diopter.

 

I chose to go with the parfocalizing rings myself as they were dirt cheap on Amazon. Now I can move my MB II diopters though the full range without problem.

 

attachicon.gif Screenshot 2024-02-05 140145.png

I have the same issue with a pair of 30mm pseudo-matsuyamas. One is an Orion Ultrascopic and the other is a Tutthill rebrand.

 

They are the same eyepiece, made in the same factory, but in different years, and clearly to a slightly different spec because the 1.25” barrels have a difference of ~2mm in height.

I got tired of always backing out one of them to come to focus and installed parfocalizing rings on both.  They lift the eyepieces up just enough that the bottom of the longer barrel no longer bottoms out in the binoviewer and now they’re both parfocal.

 

You can also use the same strategy to fix eyepiece retention issues with undercuts and barrel tapers.

 

My Sterling Plossls don’t play well with the Denk2’s eyepiece collets due to the barrel safety taper, but with a parfocalizing ring there are no issues.

 

The only issue is you need a little extra back focus.


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#13 .mike

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Posted 05 February 2024 - 04:06 PM

I have posted on this elsewhere several months ago.

 

As others have said, it is not the binoviewer or the eyepieces, it is the combination of the two. 

 

These eyepieces have a relatively long barrel, and if your diopter is too low on one side or the other or both) you can run out of inward travel as the end of the eyepiece barrel contacts the limit ring in the bino that keeps the end of the barrel from hitting the prism.

 

The solution is to use parfocalizing rings or start with both diopters all the way up/out, focus with the eye that need the most outward travel, then shorten the opposite diopter.

 

I chose to go with the parfocalizing rings myself as they were dirt cheap on Amazon. Now I can move my MB II diopters though the full range without problem.

 

attachicon.gif Screenshot 2024-02-05 140145.png

 

https://www.amazon.c...e?ie=UTF8&psc=1

to prove to myself the eyepieces were not exactly the same, I bypassed my bino's and put the zoom eyepiece into the regular diagonal.  When I got the eyepiece to perfect focus on a stationary target, I swapped zoom eyepieces and the 2nd eyepiece was NOT in focus.  Physically the eyepieces look exactly the same.

 

Unfortunately I came to the conclusion I'll have to get parfocalizing rings to try to fix this as you stated, but had I know this happens with Svbony Zoom's I would have just skipped them and gotten Nagler Zooms.  I read so many good things about the Svbony's and it never occurred to me they could be manufactured to a different spec 


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#14 kroum

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Posted 05 February 2024 - 05:37 PM

to prove to myself the eyepieces were not exactly the same, I bypassed my bino's and put the zoom eyepiece into the regular diagonal.  When I got the eyepiece to perfect focus on a stationary target, I swapped zoom eyepieces and the 2nd eyepiece was NOT in focus.  Physically the eyepieces look exactly the same.

 

Unfortunately I came to the conclusion I'll have to get parfocalizing rings to try to fix this as you stated, but had I know this happens with Svbony Zoom's I would have just skipped them and gotten Nagler Zooms.  I read so many good things about the Svbony's and it never occurred to me they could be manufactured to a different spec 

Zoom eyepieces are an order of magnitude more difficult to get right in all aspects than regular eyepieces.

 

Ar least, that’s a problem there is an easy workaround for, as well as an inexpensive solution with the parfocalizing rings.

 

I tried a pair of SVBONY’s cheaper zooms, I think they were the 9-27mm variety.

They worked fine at both extremes of the zoom range, but anywhere in the middle of the zoom range, and the internal optics would come out of alignment and I couldn’t merge the images. I promptly returned them.  Otherwise, on their own individually they were decent optically.


Edited by kroum, 05 February 2024 - 05:38 PM.

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#15 ZX12

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Posted 05 February 2024 - 11:32 PM

I use a pair of the Svbony 3-8mm zooms in my APM150 binotelescope and in the APO BV from Denis. They have been excellent performers and compare well with more expensive e.p's.

 

My pair is relatively parfocal through the range with only a slight tweak to get perfect focus.

 

No problem on height, but they do have more eccentricity of the barrel in relation to the optical center. This can help when trying to merge the image as the circles will overlap at some point when rotating the eyepieces.  

 

Mike

 


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#16 denis0007dl

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Posted 06 February 2024 - 04:50 AM

I use a pair of the Svbony 3-8mm zooms in my APM150 binotelescope and in the APO BV from Denis. They have been excellent performers and compare well with more expensive e.p's.

 

My pair is relatively parfocal through the range with only a slight tweak to get perfect focus.

 

No problem on height, but they do have more eccentricity of the barrel in relation to the optical center. This can help when trying to merge the image as the circles will overlap at some point when rotating the eyepieces.  

 

Mike

I use same setup (APO SS + Svbony Zooms), and also dont have any issue.

 

Actually, I have 3 pieces of Svbony Zoom 3-8mm epcs.

 

But what I found interesting is, that one of them have reversed built in barlow lens element than other two....

 

Denis


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#17 Eddgie

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Posted 06 February 2024 - 09:17 AM

 

 

No problem on height, but they do have more eccentricity of the barrel in relation to the optical center. This can help when trying to merge the image as the circles will overlap at some point when rotating the eyepieces.  

 

Mike

Yes, mine do this as well. I can turn them to get the image to merge though. 


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#18 ZX12

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Posted 06 February 2024 - 09:54 AM

My favorite high power setup right now is with the Svbony 3-8mm zooms in my AP140,  APO SS BV with Zeiss spec prism and 1.7x GPC.

 

Superb views of the planets and double stars the last couple months.

 

Mike 

 

 

 


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#19 Victor Martinez

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Posted 06 February 2024 - 12:15 PM

Have you compared the performance of the pair of Svbony eyepieces with other fixed focal lenses?

#20 ZX12

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Posted 06 February 2024 - 03:02 PM

Have you compared the performance of the pair of Svbony eyepieces with other fixed focal lenses?

In the average conditions of this area they perform well against Televue Delos and Baader Morpheus, offering similar levels of sharpness and contrast.

 

I've had a few excellent nights where seeing and transparency allowed a better comparison against a 4.5 Morpheus and 8 Delos. The 3-8 zoom had a similar amount of scatter on Jupiter. The surface details and moons appeared equal in sharpness.

 

With double stars the zoom does really well in the BV. Airy disks are sharp with a clean separation between tight pairs. I like the ability to use the 5mm to 8mm range (approx. 200x-300x) to find the best match for the conditions.

 

It's hard not to like the Svbony zooms, especially at that price point.

 

Mike 


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#21 Victor Martinez

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Posted 06 February 2024 - 03:50 PM

Thanks

#22 Victor Martinez

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Posted 07 February 2024 - 04:23 AM

In the average conditions of this area they perform well against Televue Delos and Baader Morpheus, offering similar levels of sharpness and contrast.

 

I've had a few excellent nights where seeing and transparency allowed a better comparison against a 4.5 Morpheus and 8 Delos. The 3-8 zoom had a similar amount of scatter on Jupiter. The surface details and moons appeared equal in sharpness.

 

With double stars the zoom does really well in the BV. Airy disks are sharp with a clean separation between tight pairs. I like the ability to use the 5mm to 8mm range (approx. 200x-300x) to find the best match for the conditions.

 

It's hard not to like the Svbony zooms, especially at that price point.

 

Mike 

I have one of these zooms that I compared very favorably to a 5 Vixen SLV and a 6.5 Baader Morpheus. Saving the distances in pupil extraction and apparent field, its optical performance seemed more than notable to me. Therefore, encouraged by the comments of Eddgie and Denis, I have purchased another one for use with binoviewer. I hope I don't have any weird problems with them.



#23 ZX12

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Posted 07 February 2024 - 09:33 AM

They have worked nicely in the binoviewer, but I did have some trouble with the big binos.

 

When I first tried the Svbony zooms in my APM150 binotelescope, the image was difficult to merge at higher powers. I thought it was either the eccentricity of the barrel/lens causing it, or the play in the upper lens when extended.

 

It turned out that my 150's were not perfectly aligned above 150x.

 

After adjusting the objectives slightly the zooms now work superbly at 275x. Now I can see the E and F stars in the Trapezium easily from 105x to 275x with just a twist of the eyepiece. It does require holding the focuser to stop it from turning.

 

The long length of the barrel does prevent the zooms from working in the APM100SD. Removing about 1-2mm's would solve it at the sacrifice of some threads for filters.

 

Mike



#24 Sarkikos

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Posted 13 February 2024 - 09:49 AM

I have posted on this elsewhere several months ago.

 

As others have said, it is not the binoviewer or the eyepieces, it is the combination of the two. 

 

These eyepieces have a relatively long barrel, and if your diopter is too low on one side or the other or both) you can run out of inward travel as the end of the eyepiece barrel contacts the limit ring in the bino that keeps the end of the barrel from hitting the prism.

 

The solution is to use parfocalizing rings or start with both diopters all the way up/out, focus with the eye that need the most outward travel, then shorten the opposite diopter.

 

I chose to go with the parfocalizing rings myself as they were dirt cheap on Amazon. Now I can move my MB II diopters though the full range without problem.

 

attachicon.gif Screenshot 2024-02-05 140145.png

 

https://www.amazon.c...e?ie=UTF8&psc=1

So, actually, sometimes it's not the binoviewer or the eyepieces, it's the eyes of the observer.  Many people need a different diopter for each eye.  

 

Mike


Edited by Sarkikos, 13 February 2024 - 09:52 AM.

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#25 Doug Culbertson

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Posted 13 February 2024 - 10:27 AM

So, actually, sometimes it's not the binoviewer or the eyepieces, it's the eyes of the observer.  Many people need a different diopter for each eye.  

 

Mike

Exactly. Before I had cataract surgery I needed diopter adjustments or to pull one eyepiece further out of the binoviewer's eyepiece holder. Now both of my eyes focus at the same point and I no longer need the adjustment. 


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