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Old 27-12-2020, 04:34 PM
Mark.Tanner (Mark)
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New eyepiece for binoviewer

My parents bought me a binoviewer for my NexStar 8SE and I need to get one/some eyepieces to go with it. I currently have decent quality Celestron 25mm, 15mm, and 6mm eyepieces and a barlow lens (the lens that comes with it plus their accessory kit).

I'm considering buying one additional 25mm, giving me two decent ranges to use due to the barlow lens. Is this a good idea, or would I be better off buying two zoom lenses?
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Old 27-12-2020, 04:53 PM
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If you want a zoom eyepiece then you need zooms with click-stops, which is only a Baader Hyperion Zoom Mk IV from what I know. If they are not click-stops then you would have lots of issues with selecting exactly the same focal lengths on both zooms and as a result bad views.

When selecting eyepieces for binoviewing they should be not only the same focal lengths, bit the same model. And preferably from the same batch. So try to buy a pair. Celestron Omni plossls are a very good start.
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Old 27-12-2020, 05:51 PM
astro744
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I use two Tele Vue 8-24mm Click Stop zooms (discontinued) with my Bino Vue and these work well. I also use other fixed length Tele Vue and Brandon eyepieces. I have never had an issue with eyepieces from different production batches as the ones I have were bought many years apart. However I have heard of one brand in particular offering matched pairs but could never understand why unless there is such a huge variation in their stated focal length that they need to do this.

The Baader will work for you provided your IPD is not less than 55mm (diameter of Baader 8-24mm Mark IV). It is an expensive option as you need two. To get started see if you can purchase another 25mm EXACTLY the same as the one you have as these are cheap and will give you a great view in your SCT with the binoviewer. One thing that you should look for is to ensure the field stop diameter of the eyepiece is not larger than the clear aperture of the binoviewer or you may see vignetting. A 25mm Plossl will have approx 21mm FSD and if your binoviewer has only 20mm clear aperture you may notice ever so slight vignetting but I would not see this an issue. The Tele Vue Bino Vue for example has 27mm clear aperture and can accommodate a pair of 32mm Plossl or 24mm Panoptic.

Have fun! Make sure the Moon is your first target at about 10 day old; it is truely spectacular in a binoviewer!
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Old 28-12-2020, 09:54 PM
Mark.Tanner (Mark)
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Thanks for the replies!

I would love to buy a couple of expensive zoom eyepieces in the future, likely the Baader Hyperion Zoom Mk IV, but for now I'll get another 25" plossl. However Celestron doesn't seem to sell separately the 25" plossl that comes with the NexStar. Does anyone know where I can buy one?
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Old 29-12-2020, 04:04 AM
astro744
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Perhaps someone else can help you with where to get this eyepiece. Otherwise consider two new 25mm Plossl (50 deg) at Bintel for $49 each.

Does your binoviewer operate at 1x or 2x mode? With an SCT 1x is Ok. You could also consider two new 15mm Superview (68deg) at Bintel for $59 each. You may be able to use two 20mm Superview (68deg) for same price but I’m not sure of their field stop diameter so you may get a little vignetting (depends on binoviewer) which may or may not be objectionable to you.

Note the shorter focal length and wider apparent field will give you more of that WOW factor when viewing the moon and with the 15mm you get some magnification you need for planets if at 1x mode. The 15mm at 135x and 68 deg apparent field will give about 0.5 deg true field which is the diameter of the full lunar disk. This is a great combo for browsing the Moon between 3 days old to 10 days old, (anytime when it’s not full).

If you want to save your dollars and put toward two zooms then see if you can pick up a used pair of something on this forum or even a matching Celestron 25mm Plossl. Binoviewing is no doubt more expensive as you need two of each eyepiece but can be enjoyable. For me personally only the Moon gives me that WOW factor in ‘stereo’ but that is plenty.
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Old 29-12-2020, 07:44 AM
astro744
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I found these on Amazon AU. Not sure if any are any good.

https://www.amazon.com.au/s?k=Zoom+e...f=nb_sb_noss_2

Here’s a review if the Tele Vue 8-24mm click-stop zoom but I doubt you’ll find one used let alone two. Note this is the only Tele Vue product that was produced by a third party (Vixen). You could search for the Vixen NLV or LV model. You need the click-stops whatever you get.

https://www.chuckhawks.com/tele_vue_click_zoom.htm
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Old 29-12-2020, 10:55 AM
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I found these on Amazon AU. Not sure if any are any good.

https://www.amazon.com.au/s?k=Zoom+e...f=nb_sb_noss_2
No, they are not good. Also they are not click-stop and therefore selecting exactly the same focal length would be a problem which will prevent you from observing in BV.
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Old 29-12-2020, 11:04 AM
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They best thing you can do is to get a pair of Starguider Dual ED eyepieces from here:

https://www.ebay.com.au/itm/2-x-Dual...d/201476615375

They are available in 5, 8, 12, 15, 18 and 25mm FL. 60 degrees FOV and good quality. They work really well in binoviewers.

Or get a pair of plössls or GSO SuperView from Bintel/Sirius Optics/Astro Anarchy/Andrew's Communications/etc
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Old 29-12-2020, 11:36 AM
Mark.Tanner (Mark)
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Is the Starguider Dual ED eyepiece a better option than the Baader Mark IV?

I like that the Baader zoom EP should be the only eyepieces that I will need to buy. The sheer quality seems to counter the negatives associated with zoom EPs, so it will at least be on par with good quality EPs at pretty much any focal length, with an exception for 30-40mm EPs. I'm happy to pay a decent amount if I'll effectively not need to buy an EP again.

I'm not sure what magnification the bino has. Can't seem to find it on the product page. How can you tell?
https://www.celestron.com/products/s...e9e3a1d0&_ss=r
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Old 29-12-2020, 02:35 PM
astro744
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The description on the Celestron site mentions their binoviewer is suitable for telescopes with at least 3.5” back focus. They also mention the unit may not come into focus with Newtonians. This to me indicates the binoviewer is 1x since 2x is typically needed to use with Newtonians.

The clear aperture of the binoviewer is listed as 22mm. I would think a pair of 20mm Superview (68deg) would be a very nice low power pair with greater true field than a pair if 25mm Plossl. A pair of 15mm Superview would be a very nice slightly higher power pair for the Moon. Combined with a 2x Barlow you can then also have 10mm (20mm + Barlow) and 7.5mm (15mm + Barlow). This is all you would ever need and all options would give 68 deg apparent field. Bintel has these for $59.00 each.

The zoom is handy to determine what fixed focal length eyepiece would give the best magnification for a particular target. I have the Tele Vue click-stop 8-24mm zooms but I also have a pair of 24mm Panoptic, 19mm Panoptic and 16mm Nagler. (Looking for another 15mm Panoptic to give me a bino pair as I really like the 68 deg field). The 82 deg field of the Nagler is very nice though when binoviewed.

The zoom has a varying apparent field and in the case of the Baader it varies from 48 deg at 24mm to 68 deg at 8mm. Whilst this seems counter intuitive it is like this so the true field remains relatively constant (or close to it particularly between 16 and 8mm).

See https://www.baader-planetarium.com/e...om_mark_iv.pdf
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Old 29-12-2020, 02:49 PM
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my 2 cents worth

Hello,

I was going to suggest the ED Starguider as well, go straight to proastroz.com.au and they're $75 a pop. 60 degree over 50 is very nice gain, better eye relief at higher mag than plossls. The 25mm is not the best in the series but still rates well. You can get 6 ep's for $415.00. which is 3 pairs and a lot lighter than adding the dup barlows, remember you're going to have balance all this stuff.

The plossl really need to have blackened internals or you're wasting money, then there are the coatings etc. Also just because they say they are, really cheap plossl won't have FMC.

* coated: at least one optical surface has a single layer coating
* fully coated: all surfaces have a single layer coatings
* multi-coated: at least one surface has a multi-layer coating
* fully multi-coated: all surfaces have multi-layer coatings

A good plossl say Saxon(silver) 25mm is $67, (my fab would be the meade 4000 at $69 - astro anarchy - oos currently), which makes the starguider's good value, andrews communications offers a ED 25mm ep at $69. I have no idea if there are worth the money(they are likely from the same production line however). - andrewscom.com.au

I use the Starguider 8mm and 12mm and find them very good and with a mostly push dob the extra fov is great.


Steve
Ps. but listen to the bino users imho

Pps. Vixen LV 8-24mm zoom for $200 each are great, no they're not click stops, but if you print off a graded line paper that just ticks off min - max at say 20 notches you can get the same effect or very close too, across all zoom levels. I can only say from what I have read the Vixen LV exceeds the Baader Mk III (but why have mark x+1 if mark x was any good) by a lot, that may not be case against the MK IV and the baader has better FOV than the Vixen.

Last edited by mura_gadi; 29-12-2020 at 04:26 PM. Reason: added pps
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Old 29-12-2020, 04:26 PM
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Is the Starguider Dual ED eyepiece a better option than the Baader Mark IV?
Optically - yes, Starguider Dual ED is better than Baader Zoom. Versatile - no. However zooms (all of them, no matter what) have different issue with narrow FOV. It's very narrow at long end. So if I were in your shoes (and I was!!!) I would buy a set of simple single focal lengths. And I do have Baader zoom and I'm using binoviewing for planets and moon all the time (i.e. not observing in mono at all). But I can tell you from my experience that a set of cheap Celestron polssls are much better optically than zooms. But YMMV.

astro744 might be right in terms of magnification. However you've got SCT and SCT/MAK's are good with using binoviewer without a corrector. Still you might need a GPC (maybe x1.2 or x1.7 at maximum).

Get two 25mm or 18mm Starguiders or 20mm Plossls and try on the Moon. Then you will understand what you need. Until that all these suggestions are only theoretical and not related to your particular case.
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Old 29-12-2020, 04:33 PM
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great points

YMMV = Your mileage may vary

Until that all these suggestions are only theoretical and not related to your particular case.

Two of the best points raised, use a astronomy club when possible and try before you buy.
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Old 29-12-2020, 05:19 PM
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I only keep bringing up the Superview because I think for the money and at f10 they would be quite ok and you can decide if they provide suitable magnifications. The 68 deg field is much more pleasing than the 50 deg Plossl field (provided it is sharp of course). Nothing wrong with two Plossls though at all. I also use Brandon pairs also and these are narrower than Plossls. My preference is for the Panoptics or Naglers for the wider field of view.

My son has a 15mm Superview and it performs nicely in his short refractor (ST80). I have not tried it on my C9.25. I can offer non-theoretical recommendations in the form of two 19mm Panoptics as I know for sure these work very nicely with a Bino Vue in a C9.25 both at 1x and 2x with the amplifier/corrector in place. Note Tele Vue state that whilst their Bino Vue can be used in 1x mode in an SCT, it is better to use the 2x amplifier/corrector to remove any traces of residual spherical aberration. I can say that the view without the amplifier/corrector is quite acceptable in my C9.25.

I don’t think you can go wrong with any low cost pair and I see that you have posted a wanted ad for a Celestron 25mm. Perhaps someone will respond to that and get you started.
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Old 29-12-2020, 05:34 PM
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I only keep bringing up the Superview because I think for the money and at f10 they would be quite ok...
...
I don’t think you can go wrong with any low cost pair...
I agree. I've got 30mm SuperView and it's perfectly fine in my f9. And yes, almost any low cost pair would work fine.

The point is - there should be some staring point. SuperView, plossls, or Dual ED - doesn't matter at all. 15, 18, 20 or 25mm pair and then deciding.
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Old 30-12-2020, 06:30 PM
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I found this for you. See http://www.astroanarchy.com.au/eyepieces.html

You cannot get any cheaper than this to get started. Either a pair of 25mm Kellner for $5 each or Sky-Watcher Super eyepiece for $10 each. Either would be good in your telescope with the Kellner looking like better build quality. The Skywatcher feels like it’s made of plastic but it works OK. (My son has one with his ST80). The Kellner will have a narrower apparent field of about 40 deg.

There’s lots of other eyepieces below but to get started you can get away with 2x$5 + $15 postage.
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Old 03-01-2021, 10:09 PM
Mark.Tanner (Mark)
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Thanks for all of the amazing replies! I'm interested in buying the 20mm and 15mm superview eyepieces. I'm struggling to find them though. Are Bintel superview eyepieces the same thing?

https://www.bintel.com.au/product/bi...v=322b26af01d5
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Old 04-01-2021, 01:53 AM
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Thanks for all of the amazing replies! I'm interested in buying the 20mm and 15mm superview eyepieces. I'm struggling to find them though. Are Bintel superview eyepieces the same thing?

https://www.bintel.com.au/product/bi...v=322b26af01d5
Yes these are the ones I was referring to. Only the 15mm and 20mm are 1.25” and are $59.ea. Bintel can help you decide further if you order buy phone.
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Old 04-01-2021, 09:27 AM
Mark.Tanner (Mark)
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Thanks Astro! I really appreciate all of the help. I've just bought a pair of the 20mm and 15mm eyepieces as you suggested. This seems like a good way to go.
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Old 04-01-2021, 11:07 AM
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No worries. Hope they bring you years of viewing pleasure. I bought a binoviewer just for the Moon and it never fails to impress. With your 2x Barlow you can then get even closer on the Moon. Of course you can view planets and deep sky stuff and with two eyes it’s just a bit more comfortable but the 3D effect is much more noticeable with the Moon, at least for me that is.

Enjoy!
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