62 replies to this topic

[Bot]

I ordered the celestron BV tonight with a second svbony goldline 20mm for my 10” ES FL f5 dob w/2”/1.25” focuser.  I doubt I’ll have enough backfocus but don’t know exactly what I’ll need to go forward yet. I have a 5” EQ newt and a 4” altaz refractor as well, but I’m starting with the big dob.  I really don’t know exactly how to proceed, just kinda winging it.  Astroyesmer, your write up inspired me to take a leap, so thanks.  

[kroum]

I ordered the celestron BV tonight with a second svbony goldline 20mm for my 10” ES FL f5 dob w/2”/1.25” focuser.  I doubt I’ll have enough backfocus but don’t know exactly what I’ll need to go forward yet. I have a 5” EQ newt and a 4” altaz refractor as well, but I’m starting with the big dob.  I really don’t know exactly how to proceed, just kinda winging it.  Astroyesmer, your write up inspired me to take a leap, so thanks.  

If the Celestron binoviewer comes with a 2x optical path corrector, you should be fine, otherwise you’ll need to get one.

 

the 1.6x Omegon I mentioned in my previous post most likely won’t give you enough back focus, but if you have (or install one) a low profile focuser, it will probably work.

[Bot]

The celestron doesn’t come with a barlow, but I purchased a sv118 2X Barlow that is 2” long that was discounted to less than $11 shipped from Amaz.  Tried to slip in another to the order but it wouldn’t honor the 50% discount, only one per customer.  So I hope this will get the dob to bino, but I doubt I’ll be satisfied with the 20mm eyepieces.  I also have two 25mm “super plossels” to try. I think I’d save money by slowing down, like many have noted before me  thanks to all 

[betacygni]

The celestron doesn’t come with a barlow, but I purchased a sv118 2X Barlow that is 2” long that was discounted to less than $11 shipped from Amaz. Tried to slip in another to the order but it wouldn’t honor the 50% discount, only one per customer. So I hope this will get the dob to bino, but I doubt I’ll be satisfied with the 20mm eyepieces. I also have two 25mm “super plossels” to try. I think I’d save money by slowing down, like many have noted before me thanks to all

A standard (not designed for binoviewing) barlow will give different magnification than it’s advertised as for mono use. Depends on design, but expect a 2x standard barlow to give at least 3x when used with a binoviewer.

Edited by betacygni, 26 December 2023 - 12:41 PM.

[Bot]

I obviously didn’t think this through.  My 2” focuser only has 45mm of backfocus, and has a tall 1.25” adapter on top.  The celestron on sale enticed me into not thinking it through.  I later saw an unbranded kit that is probably the same unit that had two eyepieces and a binoviewing Barlow for $50 less.  What can I do at this point?  Try to get it put together for as little as possible, or sell it unopened and go in another direction.  I’m not sure the celestron is worthy of the cost of all the misc parts I’ll have to add to it.  If I do keep it, I’ll want to use it on my 4” f6.6 refactor and 5” f6 newt as well…Does anyone have any good ideas for a good way forward from here?  I’m a bit chagrined, but what the hell.  I’ve fallen off bigger turnip trucks  thanks

[Astroyesmer]

The best (and cheapest) way to have the BV work in a big dob or even a refractor is this:

 

https://agenaastro.c...QhoC9U0QAvD_BwE

 

I tried everything: Baader GPC, Siebert BV barlows, short high quality prisms... but this William Optic barlow nosepiece screwed on the front of the Binoviewer will make it perform its best and will work both in dobs and refractors.

 

Not only this, but it will also fix some of the prism ghosts in the BV. It will bring a magnification factor of roughly X2.25, so using a pair of 20mm eyepies with it will result in about 9mm.

 

One might think it's a lot but remember the primary purpose of a BV is to observe planets and Moon, since the light transmission is reduced with it.

 

Some of the alternatives in order to observe with the BV at native focal lenghts is the Baader prism with a refractor, or the Siebert OCAs in dobs. Costly options... I own and use both but ever since I got the Wiliam Optics barlow nosepiece they now see less and less star light: it is just way more convenient to just screw this small barlow on the BV and "plug n play", plus like I mentionned the image is cleaner...

 

If you wonder if any barlow nosepiece will work (for example the Celestron Omni barlow or the GSO shorty): yes they do, but at a higher magnification (around X3) and therefore with more aberrations.

 

Now there is another affordable option to bring the BV to focus with almost zero aberrations and at X2: the Astrotech telecentric barlow. But it's twice the price of the WO nosepiece and bigger and heavier.

Edited by Astroyesmer, 27 December 2023 - 05:07 AM.

[kroum]

I obviously didn’t think this through.  My 2” focuser only has 45mm of backfocus, and has a tall 1.25” adapter on top.  The celestron on sale enticed me into not thinking it through.  I later saw an unbranded kit that is probably the same unit that had two eyepieces and a binoviewing Barlow for $50 less.  What can I do at this point?  Try to get it put together for as little as possible, or sell it unopened and go in another direction.  I’m not sure the celestron is worthy of the cost of all the misc parts I’ll have to add to it.  If I do keep it, I’ll want to use it on my 4” f6.6 refactor and 5” f6 newt as well…Does anyone have any good ideas for a good way forward from here?  I’m a bit chagrined, but what the hell.  I’ve fallen off bigger turnip trucks  thanks

If you purchased it on Amazon can you return it?

Another option is to get the 2x Omegon optical path corrector for another $60:

Omegon Glass Path Corrector for 1.25'' bino-viewers 2X https://a.co/d/3KpL3e9

 

binoviewers are like a black hole… get too close and you get sucked in with no hope of ever coming out…

 

Once you get it working, you get used to it and all of a sudden you’re not content with only getting twice the magnification and half the field of view you’d otherwise be getting with a given eyepiece and you’ll want a lower power optical path corrector which will necessitate a new focuser or moving the primary.  Then the next step will be wanting a full 27mm of clear aperture so you can maximize the field of view of the 1.25” barrel…. And THAT requires one of the premium binoviewers… and then you’ll be wanting premium eyepieces to max out the field of view… maybe a pair of 24mm panoptics???  And that’s just the beginning…

 

Like drugs and smoking, it’s better to not get started in the first place ….hahaha *nervous laughter*

[RLK1]

Best deal for a Celestron bino on Aliexpress that I've seen:

https://www.aliexpre...!US!4892486645!

I see the included reviews with images are pretty good as well... 

[Astroyesmer]

This is not the Celestron BV though. Likely a chinese no-name copy. False advertisement.

Not to say it does not work, but probably lacks coatings on the prisms. Not Celestron. Also, I wouldn't trust random ali express reviews...

[RLK1]

This is not the Celestron BV though. Likely a chinese no-name copy. False advertisement.

Not to say it does not work, but probably lacks coatings on the prisms. Not Celestron. Also, I wouldn't trust random ali express reviews...

I disagree, these binos from China more than likely come out of the same factory and have the same internals, ie prism size and so forth, and differ only in cosmetics and included amplifier lenses. And I don't believe people went through the trouble of writing reviews and attaching images just to make things up, particularly as these reviews come from observers in different countries.

[kroum]

This is not the Celestron BV though. Likely a chinese no-name copy. False advertisement.

Not to say it does not work, but probably lacks coatings on the prisms. Not Celestron. Also, I wouldn't trust random ali express reviews...

This might have been true 20 years ago, but these days it’s no longer the case.

 

all the cheap prism binoviewers have identical internals and only differ in the injection molded plastic housings as well as the design and build of the eyepiece holders.

[Vansh]

Yeah it's probably a knock-off, it's not actually Celestron-branded. Then again yeah it's likely pretty close to the same thing internally, just different branding.

 

I took the plunge and bought one, so after it arrives in late January I can report on how it turns out. First time buying from China (...or at least, directly). It seems like AliExpress has special deals during the first couple of days of every month so that'll be in time for if anybody wants to buy it in February.

[RLK1]

Yeah it's probably a knock-off, it's not actually Celestron-branded. Then again yeah it's likely pretty close to the same thing internally, just different branding.

 

I took the plunge and bought one, so after it arrives in late January I can report on how it turns out. First time buying from China (...or at least, directly). It seems like AliExpress has special deals during the first couple of days of every month so that'll be in time for if anybody wants to buy it in February.

The model in question has been at the same price consistently on Aliexpress from the same vendor. 

PS: Aliexpress also has a "winter sale" on Jan 8th with the following coupon codes: AEUS05 for $5.00 off orders over $49.00 and AEUS10 for $10.00 off orders over $89.00.

Edited by RLK1, 06 January 2024 - 03:06 PM.

[saemark30]

I had a couple of the older Baader Celestron binoviewers. They went out of collimation with use. Is there a way to adjust the collimation with the newer model?

[RLK1]

I had a couple of the older Baader Celestron binoviewers. They went out of collimation with use. Is there a way to adjust the collimation with the newer model?

Other than by a pro, probably not...

[kroum]

I had a couple of the older Baader Celestron binoviewers. They went out of collimation with use. Is there a way to adjust the collimation with the newer model?

The prisms are glued in place and I don’t believe there is any possibility for collimation.

 

That being said, since they are glued, usually they don’t get misaligned unless they have experienced a significant drop/impact.

The image merging issues are usually related to the eyepiece holders themselves, which means that sometimes there are workarounds.

 

For instance, on my old Orion binoviewer (same exact internals as the Celestron), I can only merge the images if I screw down both eyepiece helical diopter adjusters all the way down until they are tight, and then I just back out one of the two eyepieces until both are in focus, and I never have merging issues, even with 7.5mm eyepieces.

[RLK1]

Got my "Celestron" binoviewer today and the same model noted in post #33. Just eyeballing it now and it appears to be of similar size and weight of the stellarvue unit I bought back in 2003. Although marketed as a Celestron unit the Celestron moniker does not appear on the unit. It feels substantial and maybe a bit heavier than my stellarvue model. I used an Aliexpress coupon for $10.00 off the going price so if the unit is indeed collimated, it and the supplied lenses may be a bargain in the binoviewer world. Of course, it's cloudy and rain is forecast for the weekend, too. 

[Vansh]

Yup mine just came in today too, the same one in post #33. It goes into my Nexstar 8i just fine, comes into focus without issues and without having to use any particular optical correctors (Nexstar 8i -> 1.25" visual back -> 1.25" erect diagonal -> binoviewer). I used a 25mm Super Plossl in one eyepiece holder and a Meade MA 26mm in the other (which, as far as I can tell, have identical magnifications and field of view) and the images merge just fine. I'll have to look to see if I have any other higher-magnification eyepiece pairs to test it out.

 

I'll do more sophisticated testing (brightness between left and right, etc.) in the future, but my initial impressions are that it works just fine and I get the same "this thing is right in front of me, I can almost just reach out and touch it" effect that I get with binoculars -- it feels much more "real" than looking through just one eyepiece. The unit is fairly heavy though, so you'll need to watch out for that and hope the set screws are tight so it doesn't fall off. It came with a 1.85x barlow and a 3x barlow, which I haven't tried, as well as a wipe cloth. The eyepiece holders are twist compression rings, so yes they won't work well with eyepieces that have undercuts. However, since it's put into a 90-degree diagonal anyway, the eyepieces slide downward into the binoviewer so there's no risk of them falling out. The nosepiece is removable.

 

The FOV is *slightly* smaller with the binoviewer than without, but I'm not sure if that's just because the focal length changes, i.e. since the SCT's focal length is longer with the binoviewer so the image is naturally more zoomed in and thus less FOV, versus the binoviewer inherently cutting down the FOV. At 25mm though the FOV looked pretty similar to me, only slightly smaller, basically a non-issue and may just be due to the additional magnification from the SCT's focal length change.

 

So my first impressions are that this binoviewer will work just fine, at least as a first binoviewer for someone to try out. The package was packed well, and the 2" 45-degree erect diagonal that I ordered with it (just to try out a 2" erect diagonal) also worked fine.

 

The only thing I would recommend not ordering is the company's solar filter. I bought the Angeleyes Sun Film Filter Professional Bard Baader Film for 8" SCT and while the thing works (and snaps onto the Nexstar 8i pretty well), the sun was a blurry mess. I couldn't get a sharp image at all, and it looked nowhere near as good as the example sun images it showed on the webpage for the filter (which weren't exactly that great in the first place). Perhaps it's because I'm still in the current arctic blast in the U.S. and I imagine the seeing was pretty bad today (and it was partially cloudy too), so I'll try again in the future, but I had better solar images using a jury-rigged eclipse glasses inside a cardboard cutout with the Nexstar 8i. (I didn't have time to try the cardboard cutout with the solar film in place instead of the eclipse glasses -- note eclipse glasses basically means about a 1-inch aperture, and only one opening was used.) I don't think the thing is actually solar film from Baader Planetarium, if it's reputed to be the best type to use for clear, sharp solar images as a white solar filter, since it was very blurry.

 

Anyway the binoviewer is unbranded, i.e. not Celestron, so I'm not sure if this should become its own topic (i.e. "unbranded generic binoviewer from China"). At any rate though it seems to work just fine for someone looking to get a starter binoviewer to try it out, and it's relatively cheap.

 

P.S. Since I ordered more than one item, true to their word, they included a filter for free. It was a 1.25" Angeleyes filter No. 23A (roughly red or orange-red). It screws just fine into my 1.25" Plossl, but does not have additional threads for another filter to be stacked on top of it, so it needs to be the top filter.

[RLK1]

Yup mine just came in today too, the same one in post #33. It goes into my Nexstar 8i just fine, comes into focus without issues and without having to use any particular optical correctors (Nexstar 8i -> 1.25" visual back -> 1.25" erect diagonal -> binoviewer). I used a 25mm Super Plossl in one eyepiece holder and a Meade MA 26mm in the other (which, as far as I can tell, have identical magnifications and field of view) and the images merge just fine. I'll have to look to see if I have any other higher-magnification eyepiece pairs to test it out.

 

I'll do more sophisticated testing (brightness between left and right, etc.) in the future, but my initial impressions are that it works just fine and I get the same "this thing is right in front of me, I can almost just reach out and touch it" effect that I get with binoculars -- it feels much more "real" than looking through just one eyepiece. The unit is fairly heavy though, so you'll need to watch out for that and hope the set screws are tight so it doesn't fall off. It came with a 1.85x barlow and a 3x barlow, which I haven't tried, as well as a wipe cloth. The eyepiece holders are twist compression rings, so yes they won't work well with eyepieces that have undercuts. However, since it's put into a 90-degree diagonal anyway, the eyepieces slide downward into the binoviewer so there's no risk of them falling out. The nosepiece is removable.

 

The FOV is *slightly* smaller with the binoviewer than without, but I'm not sure if that's just because the focal length changes, i.e. since the SCT's focal length is longer with the binoviewer so the image is naturally more zoomed in and thus less FOV, versus the binoviewer inherently cutting down the FOV. At 25mm though the FOV looked pretty similar to me, only slightly smaller, basically a non-issue and may just be due to the additional magnification from the SCT's focal length change.

 

So my first impressions are that this binoviewer will work just fine, at least as a first binoviewer for someone to try out. The package was packed well, and the 2" 45-degree erect diagonal that I ordered with it (just to try out a 2" erect diagonal) also worked fine.

 

The only thing I would recommend not ordering is the company's solar filter. I bought the Angeleyes Sun Film Filter Professional Bard Baader Film for 8" SCT and while the thing works (and snaps onto the Nexstar 8i pretty well), the sun was a blurry mess. I couldn't get a sharp image at all, and it looked nowhere near as good as the example sun images it showed on the webpage for the filter (which weren't exactly that great in the first place). Perhaps it's because I'm still in the current arctic blast in the U.S. and I imagine the seeing was pretty bad today (and it was partially cloudy too), so I'll try again in the future, but I had better solar images using a jury-rigged eclipse glasses inside a cardboard cutout with the Nexstar 8i. (I didn't have time to try the cardboard cutout with the solar film in place instead of the eclipse glasses -- note eclipse glasses basically means about a 1-inch aperture, and only one opening was used.) I don't think the thing is actually solar film from Baader Planetarium, if it's reputed to be the best type to use for clear, sharp solar images as a white solar filter, since it was very blurry.

 

Anyway the binoviewer is unbranded, i.e. not Celestron, so I'm not sure if this should become its own topic (i.e. "unbranded generic binoviewer from China"). At any rate though it seems to work just fine for someone looking to get a starter binoviewer to try it out, and it's relatively cheap.

 

P.S. Since I ordered more than one item, true to their word, they included a filter for free. It was a 1.25" Angeleyes filter No. 23A (roughly red or orange-red). It screws just fine into my 1.25" Plossl, but does not have additional threads for another filter to be stacked on top of it, so it needs to be the top filter.

Thanks for the above report. Given the weather forecasts in my area, it'll be awhile before I can use it. 

The one thing that impresses me right now is the weight of the unit. It does feel heavy and I was expecting a lightweight cheap piece of plastic but I'm pleased that it's not. 

Also got the filter, too. I now have quite a few of them from prior orders via Aliexpress...

[kroum]

Thanks for the above report. Given the weather forecasts in my area, it'll be awhile before I can use it. 

The one thing that impresses me right now is the weight of the unit. It does feel heavy and I was expecting a lightweight cheap piece of plastic but I'm pleased that it's not. 

Also got the filter, too. I now have quite a few of them from prior orders via Aliexpress...

The prisms are solid glass, so by themselves, they are quite heavy.  The housing into which they are glued is cast aluminum, which also adds a bit of weight.  On top of that is a very thin plastic shell that weighs significantly less than the other components.

[saemark30]

Got mine today. Fast delivery.

I tested it on the mountains with a pair of RKE eypieces. Needs the 1.8x extension to focus in my refractor.

Here is the problem. The right side is not parfocal with the left, so the eyepiece needs to be moved out by about 2mm. There is a fine adjustment on the left side that makes things work it is already in the most.

Also the right prism is not coated, the other sides have a green coating and this one is not even purple.

Shoudl I return it, ask for a partial refund? Who do I email?

[RLK1]

Got mine today. Fast delivery.

I tested it on the mountains with a pair of RKE eypieces. Needs the 1.8x extension to focus in my refractor.

Here is the problem. The right side is not parfocal with the left, so the eyepiece needs to be moved out by about 2mm. There is a fine adjustment on the left side that makes things work it is already in the most.

Also the right prism is not coated, the other sides have a green coating and this one is not even purple.

Shoudl I return it, ask for a partial refund? Who do I email?

Frankly, I'm skeptical that your unit has a problem. Parfocality may have more to do with your eyepieces or your eyes than the unit itself. Additionally, the prisms in my unit are coated as are the lenses. I doubt they just missed one in yours.  I recall reading another one of  your posts elsewhere and you had a problem as well (something about returning an eyepiece) and wanted us, ie CN members, to advise you who to email. As if we're supposed to know who you're supposed to email. Take a look at the return procedures on Aliexpress and figure it out from there. If I and others can do it, so can you...

[saemark30]

RLK1 do you work for Orion Optics UK?

I am not stupid. I tested the same eyepiece with the same eye on both sides to verify the difference was in the unit not my 2 eyes.

Second I can photo the color of the coatings to show what I am talking about. I have decades of experience knowing what uncoated and multicoated optics look like.

Third I have never returned an eyepiece or asked for advice from CN about emailing anyone.

I guess if this request is too much for you , just pass on my message.

[RLK1]

RLK1 do you work for Orion Optics UK?

I am not stupid. I tested the same eyepiece with the same eye on both sides to verify the difference was in the unit not my 2 eyes.

Second I can photo the color of the coatings to show what I am talking about. I have decades of experience knowing what uncoated and multicoated optics look like.

Third I have never returned an eyepiece or asked for advice from CN about emailing anyone.

I guess if this request is too much for you , just pass on my message.

"So the Celestron 15mm eyepiece is better than redline eyepiece?

How do I cancel an order on Aliexpress.com?"

Post #40:

https://www.cloudyni...2#entry13202759

[saemark30]

The image show my "Celestron binoviewer". The left side opening is clearly green which means it is multicoated and the right side opening is white and the reflection is much brighter so it is uncoated.

The 2 eyepieces are blue coated which colaborates with being single coated.

BTW I messaged the company which sold the eyepieces but no response: not read. I did not return them, I want to cancel the order before they are sent within a couple of hours of ordering them.

Not sure about the reviews or advice given here.

 

You get what you pay for. Or Caveat Emptor.

 

Any more doubts?

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Edited by saemark30, 18 January 2024 - 09:33 PM.