Dual Rigs

[Midnight_lightning]

I'm still agonising about which new telescope to purchase and have extended my budget several times - at least in terms of the scopes I am considering.

Now looking at 120mm - 130mm, the latter with a 0.75 reducer gives FL 585 at F4.5 which is quite attractive. 

Anyway, the reason for the post is that having extended my budget to consider some very expensive scopes I am now in the position that I could get two Esprit 120's and have a dual rig for a similar price. 

Just wondered what additional problems dual rigs pose? 

For example I use SGPro which would control the mount as usual but could it also control both FW's and Camera's (assuming twin set ups) or would I need another copy of SGPro and possibly a seperate laptop?

 

[SamAndrew]

I believe you can run two copies on the same machine, but to me it sounds like a nightmare potentially connecting two of the same camera, filter wheel and auto focuser to one PC - sounds like a recipe for lots of setup frustration getting the right one connected to the right program

My plan is to use a raspberry PI on the second scope, as you only need to control the camera, filter wheel and focuser.

SGP has an API that would allow you to syncronise two copies to capture at the same time, pause for dithering and auto focus, if you are capable of writing a program to do it. It's quite far down my todo list, as SGP doesn't run on the PI, so I would go down the route of having two Windows PCs.

[tooth_dr]

I use two copies of SGPro at the same time to run a dual rig. The second copy I just connect EFW and CCD. The first copy does all the mount control.

It means you can’t dither. For dual synchronised dithering I have used APT. It works perfectly. I switched to SGPro for the mosaic wizard but could see myself switching back.

I have two Atik EFWs attached. When I go to connect it asks for the serial number so i always connect to the right one.

The biggest issue will be hardware - getting them lined up and eliminating flexure. But if you get it sorted then a dual rig is amazing. I captured 10 hours of Ha data a few night ago, despite there only being 5 hours of darkness 👍🏼

[Midnight_lightning]

37 minutes ago, tooth_dr said:

I use two copies of SGPro at the same time to run a dual rig. The second copy I just connect EFW and CCD. The first copy does all the mount control.

It means you can’t dither. For dual synchronised dithering I have used APT. It works perfectly. I switched to SGPro for the mosaic wizard but could see myself switching back.

I have two Atik EFWs attached. When I go to connect it asks for the serial number so i always connect to the right one.

The biggest issue will be hardware - getting them lined up and eliminating flexure. But if you get it sorted then a dual rig is amazing. I captured 10 hours of Ha data a few night ago, despite there only being 5 hours of darkness 👍🏼

Like everything else in this hobby like there is an investment in time and knowledge but that just makes the rewards even sweeter  Our weather is getting so poor here that doubling up on imaging time is worth a lot.

I don't understand why you can't dither though - unless your two scopes are aligned to the exact pixel. I'm probably missing something but if the SGPro controlling the mount does a dither and the two scopes are a few pixels out of alignment isn't it ok - the images from both scopes will all have a slightly different position on the sensor? 

 

[RayD]

Dithering is an issue because if one camera is capturing when the mount dithers, it will ruin the sub as it will have trails.  Big deal with Ha particularly where you may be doing long subs.

[tooth_dr]

9 minutes ago, Midnight_lightning said:

Like everything else in this hobby like there is an investment in time and knowledge but that just makes the rewards even sweeter  Our weather is getting so poor here that doubling up on imaging time is worth a lot.

I don't understand why you can't dither though - unless your two scopes are aligned to the exact pixel. I'm probably missing something but if the SGPro controlling the mount does a dither and the two scopes are a few pixels out of alignment isn't it ok - the images from both scopes will all have a slightly different position on the sensor? 

 

It’s not just time and knowledge, it also comes down to money 😎

You can dither with SGPro, that isn’t a problem. But SGPro can’t synchronise scope 1 and scope 2. APT is better at that.  That means that if scope 1 finishes an exposure it won’t start to dither until scope 2 has finished its exposure. Some guys on here make a sacrifice of a few subs, and that’s ok if short and dithering every 5th frame, but if taking long subs it’s a big risk/waste of subs have trailed stars. 

[Midnight_lightning]

Just now, RayD said:

Dithering is an issue because if one camera is capturing when the mount dithers, it will ruin the sub as it will have trails.  Big deal with Ha particularly where you may be doing long subs.

Ah, ok yes, I was assuming both cameras would be running in sync but thinking about it that's more difficult than it sounds. 

[RayD]

I reckon it is something SG Pro may have as a feature in the future (I hope) as more people are now looking at genuine dual rigs (synchronised).

[Star101]

11 hours ago, Midnight_lightning said:

I'm still agonising about which new telescope to purchase and have extended my budget several times - at least in terms of the scopes I am considering.

Now looking at 120mm - 130mm, the latter with a 0.75 reducer gives FL 585 at F4.5 which is quite attractive. 

Anyway, the reason for the post is that having extended my budget to consider some very expensive scopes I am now in the position that I could get two Esprit 120's and have a dual rig for a similar price. 

Just wondered what additional problems dual rigs pose? 

For example I use SGPro which would control the mount as usual but could it also control both FW's and Camera's (assuming twin set ups) or would I need another copy of SGPro and possibly a seperate laptop?

 

I have my C11 and TS65EQ on the go at the same time....sometimes. But I turn Dithering OFF. Manually Dither.

I do know N.I.N.A will allow dual rigs and Dithering by making one camera setup as master. I have used it but dont use at the moment because it does crash on my machine. I have too much setup on my machine to remove SGPro which does the job...To experiment with N.I.N.A. But I do know it works....Just not on my setup.

At least its free

N.I.N.A.

[Star101]

7 minutes ago, RayD said:

I reckon it is something SG Pro may have as a feature in the future (I hope) as more people are now looking at genuine dual rigs (synchronised).

I read on the SGPro website about three months ago ....They have no plans for addressing the Dual rig dithering issue.

Edited May 8, 2020 by Star101

[RayD]

15 minutes ago, Star101 said:

I read on the SGPro website about three months ago ....They have no plans for addressing the Dual rig dithering issue.

Ah ok, thanks.  That's a real shame as this would be a great addition.

[Star101]

3 minutes ago, RayD said:

Ah ok, thanks.  That's a real shame as this would be a great addition.

Yes, I agree being a user of SGPro myself.

But if one searches the Main Sequence forum... The suggestion has been made several times over the years and its a mute response each time. A shame really.

[sloz1664]

34 minutes ago, Star101 said:

I read on the SGPro website about three months ago ....They have no plans for addressing the Dual rig dithering issue.

That's not quite true. It will not be considered in Version 3. But should be an addition in version 4.

Steve

 

[Laurin Dave]

I run a dual scope system ..  Esprit 150 with SX46 as the master and a piggybacked  Esprit 100 with an ASI1600 as the slave..  controlled by separate instances of SGPro, works like magic. Esprit 100 has slightly bigger fov..  I aligned by shimming the dovetail bars rather than going side by side.  the SX46 runs 10 or 20 minute (RGB or Lum/Ha) subs the ASI1600 2 or 5 min (RGB or NB) .. I dither every two subs on the master scope and use an OAG so lose subs when focusing as well as when dithering..   but my efficiency on the Esprit 100 in terms of good subs (ie no trailing) is in excess of 85% of that of the Esprit150 (even when both are doing Ha), partly its the mount (a Mesu) and partly its because of the ASI1600 sub length being short..  If instead I was running a second CCD with 10 or 20 min exposures and had synchronised dithering I doubt the overall efficiency would be much higher..  When I started with dual scopes I didn't dither as I didn't want to lose subs but I gave it a go and was pleasantly surprised..   so it can be done, depending on equipment  - serendipity not design!

To the OPs original question though I would think that a dual  Esprit120 system would require an EQ8 class mount as a minimum, they would also need to investigate a means of alignment..  an Esprit120 plus cameras etc will  be c 12kg so above the JTD capacity of 9kg

[Midnight_lightning]

28 minutes ago, Laurin Dave said:

I run a dual scope system ..  Esprit 150 with SX46 as the master and a piggybacked  Esprit 100 with an ASI1600 as the slave..  controlled by separate instances of SGPro, works like magic. Esprit 100 has slightly bigger fov..  I aligned by shimming the dovetail bars rather than going side by side.  the SX46 runs 10 or 20 minute (RGB or Lum/Ha) subs the ASI1600 2 or 5 min (RGB or NB) .. I dither every two subs on the master scope and use an OAG so lose subs when focusing as well as when dithering..   but my efficiency on the Esprit 100 in terms of good subs (ie no trailing) is in excess of 85% of that of the Esprit150 (even when both are doing Ha), partly its the mount (a Mesu) and partly its because of the ASI1600 sub length being short..  If instead I was running a second CCD with 10 or 20 min exposures and had synchronised dithering I doubt the overall efficiency would be much higher..  When I started with dual scopes I didn't dither as I didn't want to lose subs but I gave it a go and was pleasantly surprised..   so it can be done, depending on equipment  - serendipity not design!

To the OPs original question though I would think that a dual  Esprit120 system would require an EQ8 class mount as a minimum, they would also need to investigate a means of alignment..  an Esprit120 plus cameras etc will  be c 12kg so above the JTD capacity of 9kg

That's interesting, so if I understand correctly I could run my 20 minute NB on the guiding OAG/Scope and the 5 minute RGB on the tandem scope - and just accept that only 3 of 4 RGB's will be usable - still not a bad return.

Yes, I haven't looked at weight issues yet but will also be buying another mount - was anticipating an EQ6R-Pro for a single scope but two might be pushing it.

 

[Laurin Dave]

10 minutes ago, Midnight_lightning said:

That's interesting, so if I understand correctly I could run my 20 minute NB on the guiding OAG/Scope and the 5 minute RGB on the tandem scope - and just accept that only 3 of 4 RGB's will be usable - still not a bad return.

Yes, I haven't looked at weight issues yet but will also be buying another mount - was anticipating an EQ6R-Pro for a single scope but two might be pushing it.

 

yep... it'll depend on how often you dither and autofocus..  two 120s on an EQ6 would I think be pushing it, an alternative of course is two mounts if you have the space (although you'll need minimum EQ6 class for a single 120)..  each with its own scope and no dithering/flex or alignment issues.  You could use the EQ5/ED80 for NB or RGB to add to LRGB or L through the 120 

[Midnight_lightning]

11 minutes ago, Laurin Dave said:

You could use the EQ5/ED80 for NB or RGB to add to LRGB or L through the 120 

Interesting. I have heard of syndicate imaging where lots of people pool there data from different sources. I know nothing about it but it makes me think I could piggy back my 80 on a 120 - maybe get away with EQ6R. No doubt there are draw backs with using different captures but something else to consider. Wouldn't the 120 have better resolution - so use that for Lum/NB and use the 80 for RGB?

[Laurin Dave]

11 hours ago, Midnight_lightning said:

Wouldn't the 120 have better resolution - so use that for Lum/NB and use the 80 for RGB?

It will ..  for galaxies I do Lum on the 150 and RGB (and Ha if there is any) on the 100..   same for reflection Nebula..  for targets with narrowband I'll do RGB and some Ha on the 150 and Ha Oiii Sii on the 100..  driven by the filters I have..  

[AngryDonkey]

Hello!

I also have a dual scope setup and over the last 3 years have been evaluating pretty much every software package available to try and control both of them in a synchronised way. Up until now I did not find a satisfactory solution because for one reason or another it never quite worked 100% (Prism can do it but doesn't allow the running of a fully automated sequence, APT can do it but autofocus is lacking in sequence, NINA can do it but I had multiple other issues, Maxim can do it but is expensive and needs two computers and third party software). In the end I just ran two instances of SGP, changed from an OAG to a guide scope (to allow independent focusing of the scopes) and turned off dithering.

Since mid of last year however I've been following the development of Voyager and swapped the two instance of SGP for two instances of Voyager (one on a virtual machine). I didn't really gain anything in terms of the dual scope setup but I like the software (no affiliation) because of its capabilities and stability and I knew that the developer was working on supporting multiple scopes.  As of two weeks ago there is a new version of Voyager that can support up to four scopes on a single mount in a fully synchronised way. Over the last few days I've been running tests on my setup and the implementation is truly awesome. It's been specifically engineered to support multi scopes and allows the connection of the different 'nodes' from either the same PC or other PCs on the same network. It is only the first release of this feature but already its fully featured and it ran a number of sequences for me in a fully synchronised way i.e. from parking position to parking position.

If you are thinking about a dual scope setup then I would definitely recommend giving Voyager a try. As with any application it has a learning curve, especially because it has some very powerful features which allow a lot of automation and flexibility. But if you have the time to spend then it is definitely worth the effort.

Mike

[swag72]

15 hours ago, Midnight_lightning said:

That's interesting, so if I understand correctly I could run my 20 minute NB on the guiding OAG/Scope and the 5 minute RGB on the tandem scope - and just accept that only 3 of 4 RGB's will be usable - still not a bad return.

Yes, I haven't looked at weight issues yet but will also be buying another mount - was anticipating an EQ6R-Pro for a single scope but two might be pushing it.

 

I have a dual rig and I run SGPro with it. You cannot run an OAG in the system as while you are refocusing for example you either need to switch off the guiding or you will have a guiding trace all over the place while the auto focus runs as that will take the guide star in and out of focus.

I don't see the issue with not being able to dither either, as I either combine a mixture of the two rigs - rejection algorithms will sort out any issue there in stacking or I use a bad pixel map..... hey presto. I think that trying to synchronise two rigs so that their subs end together so that a dither can take place would waste too much time potentially. 

Edited May 9, 2020 by swag72

[Midnight_lightning]

20 hours ago, AngryDonkey said:

If you are thinking about a dual scope setup then I would definitely recommend giving Voyager a try.

Thanks, will certainly take a look at this.

[Tarun]

I have been running dual setup with Nina for about a year now and it worked fine 99% of the time. There is an option for synchronized phd2 which takes care of dithering for multi scopes on same mount

[ollypenrice]

If you can find one second hand (and don't expect it to be cheap!) the Cassady T-GAD alignment device is very robust and carries a TEC 140 on our dual TEC140 rig. It's no longer in production.

Olly

[tomato]

I run two Esprit 150s on a Mesu 200. Although the mount is up to it (although it is a hell of a lump on the move when it is slewing!) a big issue is differential flexture of the OTAs on a side by side mounting. I have a JTD adjustable saddle but it is right on the limit in terms of weight capacity, it will receive an upgrade/modification during the summer break (lockdown permitting). I would support Olly’s saddle recommendation if you can get hold of one. Once the cameras have been aligned, a large alloy bracing plate is clamped down across the top of the tube rings. Without this, the scopes will creep enough to be noticeable on 5 min subs, especially on certain scope orientations.

I use an OAG and run 2 copies of SGP on two laptops, laptop 1 running the scope, camera, focuser, mount and OAG, the other just the other camera and scope. I put up with lost frames when focusing, but I run the focus routine at the same time on both scopes.

It is quite a challenge to get it up and running, but it’s all worth it when you see the integration time racking up on every session.

[Midnight_lightning]

6 hours ago, tomato said:

integration time racking up on every session