Running two cameras.

[alan potts]

Something wish to move into in the next few weeks as I get stronger after the operation, I opened up the obsey last night and got some data before high cloud and the Moon ruined it all.

I would like to do a duel mount with the 805mm APO and maybe the Borg 77ll F 4.3 coupled with the 183MC. Can APT handle two cameras at the same time?

If so how does one do it, or would I have to run 2 APT programs at the same time and would Dither cause a problem a problem, or would I have to stop Dither.

A bit ambitious for me so lets see if you lot can walk me through it. I am using an i5 thinkpad with 4 gig of Ram but am considering putting a faster 8 gig i5 desk top outside soon.

Alan

[tooth_dr]

With the amount of trouble you’ve had I’m surprised you want double the headache?!

With regards to the pc, there is absolutely no need for anything fancy. My dual rig run perfectly fine on a 2008 dual core 4GB pc that I bought for £28 on eBay  

 

[carastro]

Dithering is very problematic with 2 cameras running.  I think there is a software that will do it, but not sure which one it is.  

I think APT will run two cameras, but need to check on that.  My experience trying to run 2 cameras was that my laptop couldn't cope with two lots of downloads and the downloads just "hung", so I have to use 2 laptops if I am running two cameras.

I guess the trickiest thing with a dual rig is getting the cameras looking at the same thing, and also orientated the same, and you may have to check this every time you set up depending on what mounting system you have.  If you have a permanent rig then it should be much easier once you have the cameras and scopes aligned.  My problem is one of cone error and so when I meridian flip my cameras are not exactly in the same position, so I have to adjust the cameras after a flip.  For me this is not too difficult as I am using the Skywatcher Guidescope mount and this is really simple to adjust and also means I can just put the scope back on the mount each time I set up and provided the cameras are orientated the same it's pretty much as I left it the previous imaging session.

HTH

Carole 

Edited November 16, 2019 by carastro

[carballada]

I am so much interested on this post because this is something that I want to do.

Until now I prefer to prepare a two complete independent set-up than offer me the option to even shoot different targets, but I am ready for the dual OTA setup if appear an option on SGP to manage it.

I think on SGP forum a lot of people is asking for this option of dual rig, but the developers are finding a lot of troubles dependind of what integration degree you want to have. Anyway seems it will be an 'extra' option to the regular SGP package, will see. 

For intance, I am not thinking to use APT anymore, even if it could manage the dual rig. I was try with NINA with no sucess (you need the 'pro' package) and of course with SGP you could run two diferent computers (one as main with the mount, the secondary only with the camera) and losse all frames when the main OTA is doin the dithering.....

This is how it looks like run my current config with two complete different set-ups. It's more flexible but more complex.

Edited November 16, 2019 by carballada

[Adreneline]

2 hours ago, alan potts said:

A bit ambitious for me

It certainly was for me Alan!

I tried it with limited success and much frustration. As Carole says if your set up is permanent then that obviously helps but mine isn't and I reckon that two cameras is 2^2 problems - it might even be a cubic relationship! I don't use APT so had to run two instances of SGPro and although the PC could cope my brain struggled! Focussing two lenses meant using two focussing systems, plus an additional dew heater and associated usb and supply cables for the camera - it all got a bit messy for me.

Good luck though! I hope you have more success that I did 🤞

Adrian

[tooth_dr]

I have to say I found a dual rig quite simple to run once set up and aligned - APT easily does multicamera dithering, and exposures etc.  You need two of everything, so that is double the weight and cost.

@carastro Carole I'm curious about your issues with cone error and meridian flips.  I would have taken images before and after a flip and never moved anything, and never came across an issues.  What did you notice that needed adjusting?  I have to say that must have been very frustrating indeed.

 

Edit - if not a permanent set up I wouldnt even consider it!

Edited November 16, 2019 by tooth_dr

[swag72]

I have a dual rig running with SGP..... I basically use one of the scopes / camera's as a slave, so one does all the plate solving etc and the other just takes pictures all night. It can be tricky to try to coordinate the two when it comes to targets and naming them. I've ended up with the slave having wrongly names images as it was still taking them on the previous target, but the main scope had moved by then! You can't dither as it stands at the moment and also for guiding you have to use a separate guide scope other wise you can't auto focus. 

If I had to do it again, I would actually run two rigs..... it would be a whole lot easier in my mind. There would be no aligning to do between the two scopes (mine are the same FOV). You could chose whether to image one target or different ones. You do lose a couple of subs when the main scope passes the meridian as the slave is merrily clicking away with no idea what the main scope is doing. 

When they are running I have 2 instances of SGP running on the PC. There's no conflict between them on the same PC. 

It's a great way to collects loads of data

[alan potts]

This may be a bit beyond me by the sounds of it. I wasn't too worried about alignment to a point as one scope will be 330mm and the other 805mm with different cameras.

I think what I may do it fit the rig up and chop and change cameras from one scope to the other, balance will not be greatly affected I would have thought. I have both the 071 and 183 registered in APT so just a case of switching. On the other hand I do have two sets of gear and many laptops,  so weather permitting could get the AZ EQ 6 back out and run that with a short focal length Borg, which I think is 331mm and shoot a different target. Need to get a bit stronger first as the the AZ is about 20kg and I shouldn't lift it yet, even though I am sure I can.

Alan

[Adreneline]

5 minutes ago, alan potts said:

I shouldn't lift it yet, even though I am sure I can.

Take care Alan. I did too much too soon and paid the price - not pleasant.

The stars will shine bright another night!

Adrian

[carastro]

Quote

Carole I'm curious about your issues with cone error and meridian flips. 

I never find I can re-GOTO the target after a Meridian flip, or at least it's not in the centre of the FOV/same position.  always end up having to re-position.  (Don't use plate solving).  However plate solving won't cure cone error because basically the scopes are not lined up after the flip.  

For example, If I centre both scopes on a bright star on one side of the meridian flip and then do a flip the bright star is on the crosshairs of one scope but not in the same place on the other but approx 1/4 of the way along one of the cross hairs for instance.  This is on my widest FOV scope, so would be even worse with higher magnification.

There is a way of correcting cone error to do with adjusting the bolts on the dovetail, but knowing my abilities I am bound to make it worse not better, so I just leave it be and live with it.

It's pretty easy to adjust with the SWGuidescope mount as it's just a turn of the wheel or bolt.

Carole 

 

[alan potts]

44 minutes ago, carastro said:

I never find I can re-GOTO the target after a Meridian flip, or at least it's not in the centre of the FOV/same position.  always end up having to re-position.  (Don't use plate solving).  However plate solving won't cure cone error because basically the scopes are not lined up after the flip.  

For example, If I centre both scopes on a bright star on one side of the meridian flip and then do a flip the bright star is on the crosshairs of one scope but not in the same place on the other but approx 1/4 of the way along one of the cross hairs for instance.  This is on my widest FOV scope, so would be even worse with higher magnification.

There is a way of correcting cone error to do with adjusting the bolts on the dovetail, but knowing my abilities I am bound to make it worse not better, so I just leave it be and live with it.

It's pretty easy to adjust with the SWGuidescope mount as it's just a turn of the wheel or bolt.

Carole 

 

Carole, I am staggered by the accuracy of the CEM 60 working on one side of the meridian, every night bang in the same place, even after the flip it is only slight out and I haven't really done an accurate PA, which may well account for it. Most times working on one side is enough for me as I rarely do more than 3-4 hours on the scope. I know you shouldn't but I like to do a few targets each nigh and repeat the next, with our weather you can get away with it, often having multiple clear nights .

As for me and cone error, I think it is best left alone.

Alan

[david_taurus83]

APT can run 2 cameras and dither as well. You have to dither every sub though. For example, in my case, I have a DSLR running 5 minute subs and a mono running 90s subs. The DSLR is set to dither after each sub. APT will take 3 x 90s subs with the mono and then pause that image plan until the DSLR finishes its sub 30s later. Then it will dither and start the 2 image plans again, and repeat.

 

Carole, you must have flexure somewhere in your setup causing one scope to become misaligned after a flip. I have just acquired the same SW guidescope bracket to try and align both scopes so will report back my findings also. If this awful weather ever clears that is.

[gorann]

A dual rig is a great idea for the obvious reason that it gives twice as many hours of data! So it is well worth the effort especially with the weather we have up here in northern Europe (Britain still included).

In one of my two obsys I am running a dual rig with two Esprits (100 and 150) and two ASI cameras (071 OSC and 1600mono) on a Mesu 200. I use ASICAP for capture on two separate laptops, one for each camera. To me it seems to be the safest and simplest option if you have more than one laptop, as you have. With one of the laptops I also control the mount with Cartel du Ciel (recommended by Mesu so I went for it and it is free) and PHD2 (I use an ST80 and a small QHY for guiding, sitting on top of the Esprit 150). I have never dithered with these cameras and do not see much need for it as they are rather noise free.

Balancing a dual rig is a bit more complicated as more things need to be balanced. This is what I did: I took each scope (with all gear attached) and put it on the obsy floor with a pencil under the dovetail bar, and moved the scope over the pencil until I found the center of gravity, which I marked on the bar with a piece of tape. I did this with both scopes. (I used a pencil as I had one at hand - any round bar would of course do the job). I then put the dual-rig bar on the floor with the pencil under it and attached the scopes in the saddles with their center of gravity centrally in each saddle. I then slided the dual-rig bar over the pencil to find and mark the center of gravity for the whole set. I then removed the scopes and put the dual-rig bar into the holder of the mount with the marked center of gravity centrally. The scopes were then put back on (center of gravity centrally again) and I finally balanced the RA axis the usual way with the weights on the weight bar. Did that description make sence?

To align the scopes I use one of these as saddle for the lighter scope:

https://www.firstlightoptics.com/misc/jtd-dual-rig-telescope-alignment-saddle.html

 

Edited November 16, 2019 by gorann

[Laurin Dave]

Hi Alan

Like Goran I have Esprit 150 and Esprit100 but have them piggybacked.  The 150 has an SX-46 CCD on it and the 100 an ASI1600 cmos..  the 100 combo has a slightly larger fov and I aligned the scopes with shims..  image scales are similar at 1.5/1.2 arcsec/pixel. Both controlled by SGPro with the  150 as the master.. I dither and use an OAG and so lose 15-20% of the subs from the 100 but that’s still 80% more data than I’d get from one scope..  I have this setup to make the most of the UK’s cloudy skies..   and for Nebula take Ha, Oiii, Sii through the 100 and RGB Ha though the 150, for galaxies RGB through the 100 and Lum through the 150. 

what is your objective?  Is it a close up and a wider field image to give it context ? If so you may find that having the scopes aligned doesn’t give the optimum framing for one or the other.. ( will depend on how large the larger fov is) is it to combine Narrowband or lum with colour at similar image scales?  Etc 

Unless you are doing the later then given your excellent skies I’d just run two setups if you can get two mounts in your observatory.. more flexible simpler and you can still image the same target in different wavelengths..  

 

Dave

 

 

 

[Whirlwind]

If you have MaximDL then potentially you have the software from the Curdridge Observatory that can run 2/3 set ups but you need to have a different computer for each system I believe:-

http://astro.neutral.org/software/multiple-camera-sync-maxim.html

 

[carastro]

Quote

Carole, you must have flexure somewhere in your setup causing one scope to become misaligned after a flip. I have just acquired the same SW guidescope bracket to try and align both scopes so will report back my findings also. If this awful weather ever clears that is.

If I had flexure the guiding would not work on one of the cameras.   No it's definitely cone error,  I get the same problem when I use a single scope and camera, the target is not in the centre of the FOV after a Meridian Flip, sometimes not in the FOV at all!!!

Carole 

 

Edited November 17, 2019 by carastro

[carastro]

In case any-one doesnit understand cone error, see attached.  Describes my problem exactly.

It probably makes it worse because my second scope is mounted piggy back and even further from the axis. 

 

Edited November 17, 2019 by carastro

[alan potts]

Carole, cone error to me is when your ice-cream drops off.

Alan

[Laurin Dave]

That happened to me at Barry Island once 😕

[david_taurus83]

12 hours ago, carastro said:

If I had flexure the guiding would not work on one of the cameras.   No it's definitely cone error,  I get the same problem when I use a single scope and camera, the target is not in the centre of the FOV after a Meridian Flip, sometimes not in the FOV at all!!!

Carole 

 

Yes, you may have cone error between your mount saddle and the first scope. We all probably have. My GOTOs are never accurate but I plate solve so it's not an issue. What I meant was your top scope is probably sagging somehow forcing you to readjust the alignment after a flip. Less than half a millimetre makes a big difference to pointing.

[Laurin Dave]

Carole..  just a thought but maybe focuser/camera droop as they turn upside down 

Dave

[carastro]

Plate solving (if I used it) would work for a single scope, but still need to adjust the 2nd scope if using the dual rig.

I use the dual rig a lot, and because I know I need to make this adjustment after a Meridian flip, I always stand next to the scope when I do this, it doesn't take much time to adjust, I just need to go to a bright star before going to my target.

I am a manual type of girl really, doesn't bother me if I don't have everything automated.  i.e. I have EQmod but prefer using the handset, I have platesolving but not yet managed to get it working, but will make an effort over the winter when I don't have access to dark skies.

I don't have autofocus, because it is more bothersome and expensive to me to have to fit autofocus to 3 different scopes, and find a way of running them than standing next to the scope and twiddling the focusser with my fingers.

Carole 

 

 

[carastro]

Quote

 just a thought but maybe focuser/camera droop as they turn upside down 

Suppose slightly possible.  Still has the same effect though.

Carole 

[tooth_dr]

I’m still not sure this is cone error playing a role here. If scope 1 is adjusted to be pointing to the same place after the flip then scope 2 must be still pointing to the same place it was before. Unless it’s moving separately from scope 1.  My flips never point to the same place with scope 1 but once centred again, scope 2 is always in the right place. I didn’t adjust my dual rig once in the couple of years I used it. 

[Anne S]

I tried a piggybacked dual setup last year for a short time. I only used one laptop using Maxim dl 5 for the main scope and camera controlling aiming, platesolve and guiding with AstroArt4 just controlling second scope camera. I didn't have any problem with laptop dealing with the subs as they came in. It's an old W7 Pro dual core laptop, the model that's slightly below an i3. My only problem is that I couldn't image high up as the second telescope was looking at the dome roof!

I'm going for side by side next time, once I'm happy with my Cem60ec mount.