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Binoviewer usage, Xcel LX's or Svbony Zoom 8-3mm?

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#1 Kim2010

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Posted 26 January 2024 - 10:47 AM

I am planning to get a Maxbright II BV, and I am planning to use either my 2 Celestron Zoom 8-24 or separate XCel-LX eyepieces and also possibly 2 Svbony Zoom 8-3mm. What do you think? Are Zoom eyepieces okay for this use or will I be better off just buying pairs of, say, Xcel LX eyepieces? For now, I can't afford pairs of Naglers or higher end EP, so I guess Xcel LX and that level would be excellent as well for the price.

 

Wachathink?



#2 mikeDnight

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Posted 26 January 2024 - 11:09 AM

You don't need Naglers! All you need to get views that will leave even a stunning Super Monocentric behind are a good pair of mid range ~25mm & 18mm plossl's or ortho's in your binoviewer, and a 2X barlow attached to your binoviewer's nose piece. It will give you an approximate 4X amplification, good eye relief, and outstanding lunar and planetary views that will outperform any single eyepiece view in terms of that all important definition. No need for short focal length eyepieces at all!

 

I rarely use single eyepieces anymore other than for deep sky and double star observing, and also hardly ever use the short focal lengths in my binoviewer. The eyepieces I use are mainly old 5 element Ultrascopic's and Ultima's.

 

20230908_110317.jpg


Edited by mikeDnight, 26 January 2024 - 11:36 AM.

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#3 Eddgie

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Posted 26 January 2024 - 01:45 PM

I am planning to get a Maxbright II BV, and I am planning to use either my 2 Celestron Zoom 8-24 or separate XCel-LX eyepieces and also possibly 2 Svbony Zoom 8-3mm. What do you think? Are Zoom eyepieces okay for this use or will I be better off just buying pairs of, say, Xcel LX eyepieces? For now, I can't afford pairs of Naglers or higher end EP, so I guess Xcel LX and that level would be excellent as well for the price.

 

Wachathink?

I use the 38mm zooms, but my GPC is 1.7x (really 1.5x) so in my 910mm focal lenght refractor, it is rare to use the 5mm or shorter.  If I went to the 1.25x GPC, these would be more useful.

If you are using the MB II, because of the long barrels on the SBV zooms, you will not have full focuser range on the BV focusers because they barrel will bottom out when your focus position is lowest.  I solved this simply by putting Parfocalizing rings on both eyepieces, which lifted them just enough to give full focusing range. 

 

One last thing.. When you use very short focal lenght eyepieces, even a slight misalignment in the eyepieces or the binoviewer can give you merging issues.  In my case, I think it is the eyepieces and by rotating them a bit here and there, I can bring both sides to the point where I can merge them, but not everyone might be able to. Not a problem for me because again, it only happens at the highest powers and these are not powers I use much. Also, if you use a GPC or Barlow for high power work, if this will reduce the effect of any misalignment in the binoviewers.  I do think though that in my case, it is something to do with the eyepieces. At 350x, I can see that a star or planet will move in a very small circle when I rotate the eyepieces, with one being a bit more than the other, though as I mentioned, I am able to get mine to merge.  It could be something with the parfocalizing rings as well. 3mm is a lot of magnification for any errors at the focal plane. 

 

Anyway, I use the 3-8s for almost all of my planetary and lunar, and I love them. I still might go to the 1.25x GPC though. 


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#4 betacygni

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Posted 26 January 2024 - 11:47 PM

I’ve used nearly every binoviewer eyepiece available, from expensive Televues to $30 plossls. Price doesn’t always tell how well eyepieces perform in binoviewers. For example I preferred my $60 plossls to my since sold $500 24mm panoptics. For binoviewing comfort is absolutely the most important, this usually means narrow eyepieces like standard plossls/orthos.

Second to comfort is performance. Since binoviewers are nearly always barlowed in some fashion, the edge correction that you often pay for with expensive eyepieces isn’t needed (since the effective focal ratio slows down, being easier on eyepieces). Less elements often means a better performing eyepiece. Again plossls win.

Last apparent field of view. Again this is often what you pay for with expensive eyepieces. Binoviewers give the optical illusion of a greater apparent field of view, I’m entirely happy binoviewing with 50* AFOV eyepieces. Plossls again!

If I had to do it over I’d just buy as nice of Plossls as I could afford down to about 18mm (lower than this eye relief can get too small), then use barlows/glasspaths to get higher power.

More direct to your question I’d avoid the Xcels, a chance they will be too wide physically to be comfortable. I’d look to Baader orthos/plossls, or if budget allows, Televue plossls (or the Takahashi TPL best of all
if you can really stretch the budget). It’s often cheaper to have just one or two sets of nicer eyepieces, but multiple glasspaths.

Zooms can also be a good option though if you’re willing to accept the compromise of possibly less comfort (wider), and a little bit of performance loss to most fixed focal length eyepieces. It is very nice not to have to swap out eyepieces, especially in binoviewers. I’ve used zooms for many years happily in binoviewers, but in long run just prefer the comfort of narrow fixed focal lengths.

Edited by betacygni, 26 January 2024 - 11:56 PM.

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#5 Kim2010

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Posted 27 January 2024 - 04:36 PM

I use the 38mm zooms, but my GPC is 1.7x (really 1.5x) so in my 910mm focal lenght refractor, it is rare to use the 5mm or shorter.  If I went to the 1.25x GPC, these would be more useful.

If you are using the MB II, because of the long barrels on the SBV zooms, you will not have full focuser range on the BV focusers because they barrel will bottom out when your focus position is lowest.  I solved this simply by putting Parfocalizing rings on both eyepieces, which lifted them just enough to give full focusing range. 

 

One last thing.. When you use very short focal lenght eyepieces, even a slight misalignment in the eyepieces or the binoviewer can give you merging issues.  In my case, I think it is the eyepieces and by rotating them a bit here and there, I can bring both sides to the point where I can merge them, but not everyone might be able to. Not a problem for me because again, it only happens at the highest powers and these are not powers I use much. Also, if you use a GPC or Barlow for high power work, if this will reduce the effect of any misalignment in the binoviewers.  I do think though that in my case, it is something to do with the eyepieces. At 350x, I can see that a star or planet will move in a very small circle when I rotate the eyepieces, with one being a bit more than the other, though as I mentioned, I am able to get mine to merge.  It could be something with the parfocalizing rings as well. 3mm is a lot of magnification for any errors at the focal plane. 

 

Anyway, I use the 3-8s for almost all of my planetary and lunar, and I love them. I still might go to the 1.25x GPC though. 

 

do you think 2 25mm Plossls would be just the same for BV use than 2 25mm Xcel LXs?



#6 lwbehney

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Posted 27 January 2024 - 07:57 PM

Congratulations on your decision to get a binoviewer. It will rapidly spoil you. I rarely look at planets without it and I never look at the Moon without it. Your brain will process the input from both eyes and the final image your mind perceives is better than a mono view.

My two telescopes required me to purchase the Baader 32 mm prism diagonal and the 1.25X GPC in order to allow my Bino Vue to reach focus and still have some decent true field of view remaining.  I am using a pair of 32 mm Brandon eyepieces for wide field. I compared them to a pair of standard inexpensive 25 mm Plossl eyepieces and indeed they are better, so I recommend you get a brand of Plossl with at least a fair reputation.

 

 I would also echo betacygni in his experience of finding that by virtue of having both eyes available, the otherwise cramped field of view of a Plossl eyepiece feels expansive and comfortable in a binoviewer. Nevertheless, for the Moon, an eyepiece with a wider field of view is of great benefit, because of the huge amount of lunar terrain this opens up during your searches for specific formations, or spacecraft landing sites. I love my pair of Morpheus 17.5 mm for this purpose. I will say that I hate the pair of Baader 10 mm BCO eyepieces I bought, because the eye relief is uncomfortably tight for me. 

 

Lastly, MikeDnight is absolutely correct in his recommendation to use a Barlow and mid-focal size Plossl eyepieces for high power views. 


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#7 kroum

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Posted 27 January 2024 - 10:17 PM

While it is definitely true that a binoviewer will make the ~50 degree field of view of Plossls feel wider, the same thing applies all the way up.

 

A pair of super wide eyepieces feel like ultra-wide, and a pair of ultra-wide eyepieces feel like the telescope just goes away and you’re just looking up at the sky with your bare eyes.

 

Typically, eye placement becomes trickier the wider the apparent field of view of the eyepiece is, and having proper eye placement for both eyes simultaneously is significantly trickier than for just one eye, so ultimately there is a balance to be made between apparent field of view and ease of eye placement/ergonomics.

 

For some people, the ideal balance favors narrow fields of view and easy eye placement, while others prefer a more space walk feeling at the expense of being very precise with viewing positioning and maneuvering as you look from one edge of the field of view to the other.

Your personal preference will probably also change depending on the target or how tired your are, or even your mood.

 

Binoviewers are a black hole for eyepieces…

 

That being said, you can’t go wrong with a pair of Plossls.

 

And that being said, I’m waiting on a second 25mm Xcel-lx to be delivered to see if I like them better than Plossls.

 

Mind you, I have pairs of the following already:

30mm Ultrascopics  (I really wanted to like these, but eye relief is uncomfortably long and eye placement is very finicky)

26mm Plossls (lenses are too narrow and the eye lens vignettes the view due to the increased eye relief from the binoviewer OCS)

25mm Vixen NPL (adjustable eye guards are garbage and don’t stay where you put them, field of view is restrictive for a Plossl at 50 degrees vs. the 52 degrees that most other Plossls are)

 

I had previously bought a pair of 27mm Flat Field eyepieces a while back from Amazon, but I returned them because at the time I had a binoviewer with smaller clear aperture and they vignetted pretty badly.

I was thinking of giving them a try again because I remember eye placement being very easy, but then the 25mm Xcel-lx kept being mentioned in threads I was reading, always in a positive context, and it’s supposed to be optically identical to the now discontinued Meade 5000 60 degree eyepieces that had great reviews back in the day for sharpness, contrast, as well as off-axis correction in fast scopes.


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#8 preprius

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Posted 27 January 2024 - 11:01 PM

I have 3 pairs. used in my 2800 fl cpc1100

I don't use the little doubler because my focal length is 2800mm.

 

13mm Stratus 68*  > 215x magnification

15mm 5000 Meade UHD 65* >  186x

27 Ef Orion.    >   103x

 

most comfortable are the Meade 15mm.  

13mm give great views of M13 and Jupitor. 

 

27mm gives the widest tfov 0.51*  (not much)

 

Today I was looking and calculating of 24mm hyperion hoping 68afov would give me a better tfov than my 27mm, but it calculates at 0.55* tfov.  I doubt I can see 0.04 deg difference.

 

Mark Eason (Me.)


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