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Nexus II Review


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Nexus II Review

 

SUMMARY: The Nexus II is an outstanding piece of equipment that allows anyone to use their Smartphone or tablet and see where their telescope is precisely pointed. It is an extremely cost effective and easy way for someone to add digital setting circles and a “Push-To” function to just about any telescope.

 

 

Nexus-II - Digital Setting Circles | Astro DevicesThe Nexus II is one member of a family of digital setting circles devices developed by Serge Antonov, owner of Astro Devices. While the Nexus DSC product itself is a full featured DSC system consisting of the hardware/software and LED displays that enable anyone to dial in a selected astronomical object, the Nexus II is essentially the same thing, minus the digital readout. It takes the input from a pair of encoders mounted to the telescope and wirelessly displays where it’s pointed on a tablet or Smartphone. This is a review of only the Nexus II and to use it you also need an app that will interface with the unit. For my purposes I use Sky Safari 5+ on an Android device.

A quick background: I built my 12 ½” F5.2 Dobsonian telescope, described in a CN article here, with “manual” setting circles and by manual  I mean a printed 360° azimuth circle glued to a 18” diameter hardboard ring that encircled the rocker box of the telescope. For altitude I used a digital inclinometer. After going through a tedious alignment procedure to level the telescope and point it and the 0°/360° mark of the azimuth ring precisely north I would then look up the Alt/Az coordinates of an object I would want to view. Once the telescope was slewed to the specified coordinates I was usually in the neighborhood of what I was looking for but I still had to resort to old fashioned star hopping to zero-in on the object itself. It was far from a perfect system and I wanted something more efficient.

After a thorough search I selected Astro Devices for several reasons.

1.    Most important; Astro Devices provides a one-stop shop supplying everything I would need and by everything, I mean the encoders and mounting hardware specific to my type of telescope as well as the Nexus II itself. I felt in case of an “issue” I would only have to deal with one person, one company and not have several different vendors pointing fingers at anyone else.

2.    Serge’s customer support reputation, as described on CN, was outstanding. I expected at some point I would need some help (more on that later) and he did not disappoint.

3.    I saw no reason to spend the extra money for a DSC system with a digital readout. I reasoned that this era’s Smartphone or tablet has more than enough computing power to do that. The Nexus II basically tells the app on my phone where the telescope is pointing.

I emailed Serge the specifications of my telescope, he emailed me back with some specific questions regarding some needed dimensions such as the distance from the center point of the altitude ring to the base of the scope and I received the kit (from Australia) that included everything I needed, all for a total cost of $350.00 ($200 for the Nexus II + $150 for the encoders and hardware.)

IMG_20200808_225727 (2).jpgThe package included, in addition to the Nexus II device, a pair of 8196 step magnetic encoders with all the wiring and connectors as well as all the mounting hardware and instructions.  Installation was easy and accomplished in about an hour. It’s important to note, one critical piece of hardware needed and included with the kit is a modified stainless steel azimuth axis pivot bolt, one with a head that has a machined out socket for the encoder shaft, and a tapped setscrew to lock it in. For other scopes you might need something else but there are numerous kits shown on the Astro Devices website for different brands and types of telescopes. For my case, because it’s a home built scope I also needed to tell Astro Devices the exact length pivot bolt needed.

IMG_20200808_225907.jpgThe Nexus II itself is housed in a metal box roughly 3” x 5” x 1 ¼”, small enough to fit inside the base of the rocker without interfering with the bottom of the mirror box of the telescope when pointing at the zenith. It’s connected to both encoders with a single RJ-45 connector and that’s all there is to it. The internal battery is good for 11 hours of observing and since it’s a rechargeable battery, if and when it no longer holds a charge it can be replaced. (NCR18650B). It will also work with external power. After three years of use, I have not yet needed to replace the battery despite recharging it many times.

Once switched on the Nexus II creates its own little Wi-Fi network. With your smart device you connect to the Nexus network then once Sky Safari is opened and configured to the network’s IP settings, you click “Connect” and when you move the scope you will see the target on your device’s screen move. In my case, the first time I used it, when I moved the scope up the target would move down. I then simply had to change the Sky Safari encoder settings for the “Alt” axis from “+” to “-“ at which point it moved in sync with the scope in both directions.  You then go through the Sky Safari alignment process and you’re in business for the evening.

Now here’s the part where Serge’s support was critical. At some point, after two years of use with zero problems, all of a sudden Sky Safari wouldn’t connect with the Nexus II. It looked like the phone would connect with the Nexus network but once Sky Safari was launched there would be no connection. I thought it might be a battery problem so what to do? I emailed Serge and he called me on the phone (from Australia mind you, 16 hours ahead). We stepped through a couple of tests and he confidently diagnosed that somewhere along the line an Android update was causing my phone, because it detected no internet access, to automatically disconnect from the Nexus network and reestablish contact with my home network. Whether or not this would happen out at a remote site with no home network in range I wouldn’t know since I never tried it but the solution was to tell my phone to “forget” my home network. By doing this, the phone stayed in contact with the Nexus II without any issues. Once done for the evening I would simply reestablish my home network on my phone. Note: Android has since issued another update where a pop-up window now asks if I want to continue to use the Nexus network. If you don’t answer “Yes” you will lose the connection.   

Whenever I observe I’m always absolutely stunned with how well the whole system performs. When in use, the Nexus II is extraordinarily accurate. (And when I say “Nexus II” I mean the entire system, the device, the encoders and app). I can select whatever I want to look at on Sky Safari, move the telescope where indicated and the object, without fail, will be within the field of view of an 18mm eyepiece. I no longer need to even bother with my scope’s finder and it makes an evening’s observing session so much more efficient and rewarding. I have since removed both the azimuth circle and the inclinometer from my scope. They’re no longer needed.

I can highly recommend the Nexus II as well as the encoders supplied by the company for those who want to add a very accurate and reliable DSC system to their telescope but are looking for something a little more economical than a full blown self contained system.  For those who might be unsure about dealing with someone in Australia, rest assured Astro Device’s support is top notch but there are also several dealers that have been set up in the US as well as the UK, Europe and Japan. If you want a reliable, easy to install “Push-To” DSC system, this is the one to get.

 

 


  • Jeff Morgan, paul, Denkmeier,Inc. and 22 others like this


62 Comments

Fo the 12" it might be better to go with the higher resolution azimuth encoder. If it was a 10" then it would not give you a lot of advantages.

 

Best Regards,

Serge.

Serge,

 

Can you elaborate on the differences with the 12" scope and the two encoders? I received my package from you ( thanks) but did order the lower resolution encoder setup for my 12 and am now wondering if I made a mistake.

 

Thanks

 

Brian

Serge,

 

Can you elaborate on the differences with the 12" scope and the two encoders? I received my package from you ( thanks) but did order the lower resolution encoder setup for my 12 and am now wondering if I made a mistake.

 

Thanks

 

Brian

While I generally feel confident in any recommendation Serge would make, I can state, as I described in my article, that the 8196 magnetic encoders work just fine on my 12 1/2" scope. In fact, the pointing accuracy is actually better than what I described. For example, last night, while waiting for Mars to rise above the treeline, I was hopping about all over the sky looking at this and that with an 8.8mm 82° FOV E.P. and the objects (doubles, clusters, various Messier objects) I wanted to view were consistently right there. Maybe not dead center, but there within the F.O.V. nevertheless without me needing to resort to any zig-zag movments of the scope to gather them in. Now maybe that's a function of the precision I used in building my scope but still, I wouldn't hesitate to recommend the 8196's, at least in an F5.2 scope.

 

I'll also add that the network drop problem I described in my article seems to only affect Android devices and the latest update resolved the issue. Android will ask, "The network you connected to does not have Wi-fi access. Do you still want to stay connected?" You need to check the "Yes"  box fairly quickly so you don't lose the connection.

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gatorengineer
Oct 19 2020 08:30 PM

Any one have problems with skips and lags with SS6 Pro?  Just got my nexus after 2 Betis and first night out had alot of skip issues,  smooth movement then hang then jump in SS6, I assume its SS6 by the way.  SS2 was alot better in many ways.

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carolinarider
Nov 01 2020 09:56 AM

Just received my Nexus-II this past Friday.  Have not actually used it yet but have it setup and communicating with my computer in the observatory using the encoders on my 12.5" equatorial mount.

 

Not sure how old the encoders are but it was a simply plug and play connection to the Nexus-II device.  

 

So far I am very impressed with the units design and operation.   

Let me add my thanks for the review and appreciation for the Nexus II.

 

I worked with Don Pensack (who has posted on this thread) and Serge to determine what I needed for my 13.1" Dob, built around an old Coulter mirror, with a Dob mount built by Mark Wagner at Astrogoods.

 

After I sent a lot of specs on the mount, bearings, and connections, Serge put together a custom kit and shipped it through Don's company to me.

 

I carefully installed it, and Don and Serge helped me figure out an issue I was having (a loose connector between the altitude encoder and the shaft on my altitude bearing), and I got the system working very well with my Sky Safari 6 Pro.

 

It was worth the the wait, the money, and the effort!

 

And I was a star-hopper for THIRTY YEARS in this hobby!  lol.gif

 

Mike

Frankfort, Ky.

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Notoriousnick
Nov 11 2020 10:56 PM

After my earlier post commenting that having read this excellent review, I was going to order a Nexus II, I did just that and have been using it a while now.

 

It is everything everyone said it was - it was relatively easy to install on my SW Dob and it has made locating objects much simpler!

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startraveler68
Nov 24 2020 01:20 AM

Good to know. I've recently come into possession of an old JMI NGT-18 telescope. I'm not sure about the drive or the electronics but the optics are in good shape. I can get a Nexus II, build a Dobsonian mount for the OTA, and I'll be ready to go!

I purchased a Nexusii and Encoders for my Explore Scientific Truss 16 inch and it's amazing how easy it works.

 

I would like to Thank Serge for assisting me and I would definitely recommend this product. Thank you Serge.

 

Randy.

I have a NexusII on my ES 12in Truss DOB. Love it! But was wondering if having the rocker box level on the ground makes a difference? In my location I will have to devise something to accomplish that but will gladly do it if it will make accuracy better.

 

Clear Skies

 

Brian

I have a NexusII on my ES 12in Truss DOB. Love it! But was wondering if having the rocker box level on the ground makes a difference? In my location I will have to devise something to accomplish that but will gladly do it if it will make accuracy better.

 

Clear Skies

 

Brian

Brian,

It shouldn't make a difference as long as your alignment stars are aligned accurately.

Being level can have other benefits, such as gravity not moving the scope in azimuth or causing a mirror in a sling to shift sideways, but

it isn't necessary for finding accuracy.

Thanks Don,

 

Any other tips for my combo to obtain best accuracy? Sometimes its spot on for me, other times its fairly far off and not in FOV of say the 17mm eyepiece. Not sure what I do that makes the difference. 

 

Brian

1) make your stars at least 90° apart in azimuth and at least 5° different in altitude.

I use Polaris and a bright star in the southern sky a bit higher and get good results.

2) Make sure the scope doesn't wobble as it moves.

If the collimation changes with altitude, tighten the spider, because change in collimation could affect pointing.  Some ES dobs' mirrors move when the scope changes altitude, so check for that too.

Make certain the scope doesn't shift sideways relative to the rocker box as it moves up and down.  This plays havoc with pointing accuracy.

      Sometimes felt furniture pads inside the walls of the rocker box will hold the mirror box in the center and disallow lateral movement.  That's better than a puck on the outside.

Use a crosshair eyepiece for the 2-star alignment.  This will improve accuracy.

I presume you are using Sky Safari?

Yes sky safari, The scope is rock solid and holds collimation very well, I need to look at the rocker box and make sure there is no lateral movement, I bet that's where my issues come from. I typically align using my highest power eyepiece , 6mm at the moment. Next outing I will try the Polaris -> southern method you mention as well. 

Probably a dumb question.  If the scope feet sink a bit unevenly after a successful alignment, would this adversely impact alignment accuracy?  Or have no impact?  Haven't had enough coffee yet to think it through.

It would have an impact because the scope would no longer point at the coordinates it thinks it is pointing at.

The cure would be to do another alignment.

Thanks Don.  I have always been concerned there would be an impact.  But started to second guess myself thinking that maybe once aligned even if the scope got tilted the original relationships would have still been the same....just shifted and still be just fine.  

 

Gosh, many of use setup on less than concrete-like ground (as in grass/soft dirt, etc.), so over time the feet will sink in some for sure....even if just a tad.  So alignment could be adveresly impacted in many situations due to this.

Thanks Don.  I have always been concerned there would be an impact.  But started to second guess myself thinking that maybe once aligned even if the scope got tilted the original relationships would have still been the same....just shifted and still be just fine.  

 

Gosh, many of use setup on less than concrete-like ground (as in grass/soft dirt, etc.), so over time the feet will sink in some for sure....even if just a tad.  So alignment could be adveresly impacted in many situations due to this.

some possible cures:

--increase the diameter of the feet.  Mine are 4" and sink in very little. Even at 30 lbs per pad.

--put small pieces of masonite under the feet when setting up.  That will significantly reduce the ability to sink into soil.

 

I have set up on sand and in that case the ground board actually rested on the sand because the feet sank in.  The ground board did not sink further.

I use hockey pucks at 3 inches. Some type of wider flat square sheet of masonry or slate could help. Sounds like literally any degree of tilt could impact the precision.... even if tiny.

I have fat pads, standard 3/8 thread off amazon, on my surveyor's tripod.

 

I am generally using, even under my GPS11 Manfrotto 114 dolly wheels, sorbothane 2"x2" multilayer pads made for compressor antivibration mounts.

 

They were recommended here on CN, are available on Amazon for peanuts (the original post was for alibaba), and they seem to be awesome so far.

 

I don't have any tripods with spikes, but if I did I would use E6000 (available from Amazon, Walmart, amazing slightly flexible rigid glue that sticks to everything) to glue a fender washer to the top of a pad to make a locating hole for the spike that would also be sixes to prevent penetration of the pad.

 

 The $30-40 Celestron antivibration pads should cure your problem too, sorbothane in a plastic cup, with a central top plastic insert to accesspt the spike.

I use hockey pucks at 3 inches. Some type of wider flat square sheet of masonry or slate could help. Sounds like literally any degree of tilt could impact the precision.... even if tiny.

Tilt per se does not affect accuracy.

A change in tilt AFTER alignment will.

I believe Sky Safari allows a realignment on the target, which could compensate.

Exactly. It's the change in tilt that impacts accuracy.

Somethings still not right with my setup. Previous nights accuracy was terrible as I moved from different areas of the sky. I have shored up my ES mount and there i zero lateral movement of the mirror box. Im on concrete so the base is stable and not moving. Using the alignment method Starman1 suggested in a earlier post, but still just not right. Im wondering if the other Nexus unit that can learn your mounts irregularities would be appropriate (If it has that capability, seems I read that in the manual once).  Or perhaps I have a flakey encoder on one axis. 

Some possibles:

--slipping encoder

--bad cable to one of the encoders

--wrong encoder setting in the unit

--(if magnetic) too great a distance between sensor and magnetic strip

--low battery in unit

--line up on the wrong star

--loose azimuth axis

--wrong baud rate for communication

 

If scooting a long way across the sky, it might help to sync on a target (I think Sky Safari allows this) to improve accuracy in the area.

--slipping encoder

Will check that on the AZ encoder

--bad cable to one of the encoders

Downloaded the NexusII config utility and it seems to track the mount well and stabilize when stoped looking at the utility so I have to assume the cable is good

--wrong encoder setting in the unit

In the NexusII its set it skysafari, although when connected to the config utility it shows 8192 on both axis even though skysafari is correct for my encoders

--(if magnetic) too great a distance between sensor and magnetic strip

​Alt encoder is mag, but there is no provision for adjustment on the ES scopes

--low battery in unit

Charged before sessions

 

--line up on the wrong star

​Pretty careful here, but could happen of course

--loose azimuth axis

Are the ES rocker boxes known/prone to this? Will check and open to suggestions on fixing or enhancing this

--wrong baud rate for communication

WiFi, being a IT guy, not sure where to set this for WiFi..lol

See:

https://www.astrodev...h_SkySafari.pdf

and 

https://www.astrodev..._Manual_1.1.pdf

pages 13, 14, 15.

 

and, if you still can't get it dialed in:

email Serge at info@astrodevices.com



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