Re: UC22 and Argo Navis for imaging
It just means I'm outside for the entire session, rotating the camera, changing the filter on the slide, tweaking the focuser and collimation, checking for dew, launching another live stack. No retreating indoors for me!
Mike
Envoyé depuis l'application Mail Orange
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Envoyé : samedi 24 mai 2025 13:40
Objet : Re: [ServoCAT] UC22 and Argo Navis for imaging
That's a great way to do it ...?
g.
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------ Original Message ------
Date 5/24/2025 2:21:40 AM
Subject Re: [ServoCAT] UC22 and Argo Navis for imaging
Hi,
My approche is more manual. With my 20" f/4 Obsession and CMOS camera (ASI294MMPro), I take 5 minute live stacks, with 2 second exposures for each filter then manually rotate the camera using a graduated sale. I have written a program that tells me the amount of rotation needed for each interval. I still have some cropping to do but get a result that I am happy with.
Mike
Envoyé depuis l'application Mail Orange
----------------
Envoyé : samedi 24 mai 2025 03:36
Objet : Re: [ServoCAT] UC22 and Argo Navis for imaging
You need derotator software for the rotator.
Mickey
On May 23, 2025, at 8:55?PM, Mike via groups.io <mklosterman1= [email protected]> wrote:
?
I had tried a Pegasus Astro field rotator (the first version) but could never reach focus with all my other stuff in my image train (like starizona nexus reducer/corrector). I ended up selling it before I engineered adjustable truss poles for my 18” astrosystems dob. I may try ?again and ?get a rotator with a thinner profile. Until then, I just crop out the rotation artifacts. I am only doing EAA using sharpcap so I am not looking for perfection.
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Re: UC22 and Argo Navis for imaging
That's a great way to do it ...?
g.
------ Original Message ------
Date 5/24/2025 2:21:40 AM
Subject Re: [ServoCAT] UC22 and Argo Navis for imaging
Hi,
My approche is more manual. With my 20" f/4 Obsession and CMOS camera (ASI294MMPro), I take 5 minute live stacks, with 2 second exposures for each filter then manually rotate the camera using a graduated sale. I have written a program that tells me the amount of rotation needed for each interval. I still have some cropping to do but get a result that I am happy with.
Mike
Envoyé depuis l'application Mail Orange
----------------
Envoyé : samedi 24 mai 2025 03:36
Objet : Re: [ServoCAT] UC22 and Argo Navis for imaging
You need derotator software for the rotator.
Mickey
On May 23, 2025, at 8:55?PM, Mike via groups.io <mklosterman1= [email protected]> wrote:
?
I had tried a Pegasus Astro field rotator (the first version) but could never reach focus with all my other stuff in my image train (like starizona nexus reducer/corrector). I ended up selling it before I engineered adjustable truss poles for my 18” astrosystems dob. I may try ?again and ?get a rotator with a thinner profile. Until then, I just crop out the rotation artifacts. I am only doing EAA using sharpcap so I am not looking for perfection.
|
Re: UC22 and Argo Navis for imaging
Hi,
My approche is more manual. With my 20" f/4 Obsession and CMOS camera (ASI294MMPro), I take 5 minute live stacks, with 2 second exposures for each filter then manually rotate the camera using a graduated sale. I have written a program that tells me the amount of rotation needed for each interval. I still have some cropping to do but get a result that I am happy with.
Mike
Envoyé depuis l'application Mail Orange
----------------
Envoyé : samedi 24 mai 2025 03:36
Objet : Re: [ServoCAT] UC22 and Argo Navis for imaging
You need derotator software for the rotator.
Mickey
toggle quoted message
Show quoted text
On May 23, 2025, at 8:55?PM, Mike via groups.io <mklosterman1= [email protected]> wrote:
?
I had tried a Pegasus Astro field rotator (the first version) but could never reach focus with all my other stuff in my image train (like starizona nexus reducer/corrector). I ended up selling it before I engineered adjustable truss poles for my 18” astrosystems dob. I may try ?again and ?get a rotator with a thinner profile. Until then, I just crop out the rotation artifacts. I am only doing EAA using sharpcap so I am not looking for perfection.
|
Re: UC22 and Argo Navis for imaging
You need derotator software for the rotator.
Mickey
toggle quoted message
Show quoted text
On May 23, 2025, at 8:55?PM, Mike via groups.io <mklosterman1@...> wrote:
? I had tried a Pegasus Astro field rotator (the first version) but could never reach focus with all my other stuff in my image train (like starizona nexus reducer/corrector). I ended up selling it before I engineered adjustable truss poles for my 18” astrosystems dob. I may try ?again and ?get a rotator with a thinner profile. Until then, I just crop out the rotation artifacts. I am only doing EAA using sharpcap so I am not looking for perfection.
|
Re: UC22 and Argo Navis for imaging
I had tried a Pegasus Astro field rotator (the first version) but could never reach focus with all my other stuff in my image train (like starizona nexus reducer/corrector). I ended up selling it before I engineered adjustable truss poles for my 18” astrosystems dob. I may try ?again and ?get a rotator with a thinner profile. Until then, I just crop out the rotation artifacts. I am only doing EAA using sharpcap so I am not looking for perfection.
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Re: UC22 and Argo Navis for imaging
Hi Gabriel, and yes short exposures using some form of deep sky lucky imaging work very well with dobs doing Astrophotography. If I ever get back at it again, the move to Fl has really set my time line back. It is to dang hot.
Mickey
[Edited Message Follows]
I limit my exposures to 10-20s depending on where in the sky i image, it helps that i live 63 degrees north.
My setup is already sky fog limited after only 20 seconds despite using a DSLR, so taking short exposures is not really a problem. With the latest sensors it works even better with short subs. In fact what i find is that dynamic range is much better than when i used longer exposures on my dedicated rig.
?
For long integration times the best strategy is to image an object for say 1 hour then catch it the same time next clear night and continue like that, this way you will not have to crop as much on the final stack as if you had imaged the same object for 6 hours on the same night.
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Re: UC22 and Argo Navis for imaging
I use the Optec De-rotator system and watch the time of the exposures.?
Mickey
What do you dob astrophotographers do for field rotation? Do you have a rotator or do you just limit exposure times? I have an 18" SC/AN equipped dob and I'm looking into getting started myself. (Actually designing and building cameras from scratch!) 3D printed field rotators are a thing now, so that's what I favor at the moment.
?
Thanks,
Tony
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Re: UC22 and Argo Navis for imaging
Hi Tony,
You have some options:
Lucky imaging takes a bunch of short exposures and you align/derotate post prcessing. Let the camera software align and stack your image.
I use option #2 since the camera software is so fault tolerant. ?I use Mallincam cameras with MallncamSky software.
My UC18 with ServoCAT and Argo Navis enable me to remotely observe with my big screen TV.
Most of my image stacks are 10 stacked images with 10 to 15 second exposure each (100 to 150 seconds) with no bother about field rotation.
Good luck!
Richard?
Get
What do you dob astrophotographers do for field rotation? Do you have a rotator or do you just limit exposure times? I have an 18" SC/AN equipped dob and I'm looking into getting started myself. (Actually designing and building cameras from scratch!) 3D printed field rotators are a thing now, so that's what I favor at the moment. ? Thanks, Tony ?
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Re: UC22 and Argo Navis for imaging
I limit my exposures to 10-20s depending on where in the sky i image, it helps that i live 63 degrees north.
My setup is already sky fog limited after only 20 seconds despite using a DSLR, so taking short exposures is not really a problem. With the latest sensors it works even better with short subs. In fact what i find is that dynamic range is much better than when i used longer exposures on my dedicated rig.
?
For long integration times the best strategy is to image an object for say 1 hour then catch it the same time next clear night and continue like that, this way you will not have to crop as much on the final stack as if you had imaged the same object for 6 hours on the same night.
?
/Gabriel
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Re: UC22 and Argo Navis for imaging
What do you dob astrophotographers do for field rotation? Do you have a rotator or do you just limit exposure times? I have an 18" SC/AN equipped dob and I'm looking into getting started myself. (Actually designing and building cameras from scratch!) 3D printed field rotators are a thing now, so that's what I favor at the moment.
?
Thanks,
Tony
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Re: UC22 and Argo Navis for imaging
贵谤é诲é谤颈肠,
?
I just use my imaging camera for the 2-star alignment step. ?I have a remote handpad to slew the scope close enough with help of a telrad and center the star on my remote laptop screen. ?Once aligned, I focus on the last star I used with my 3D printed mask, place the AN into From Planetarium mode , remove the mask and retire to my recliner for the evening of remote observing and cast to the big screen TV. ? ?
?
Remote focus and remote slewing keeps me in my recliner. ?Sometimes I do go out and peek into the Telrad to see when a target will clear my tall Pine trees. ?It is on my todo list to load my horizon obstacles into Stellarium.
?
Richard
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Re: UC22 and Argo Navis for imaging
Hi Sevan, I am the guy with an UC22 Servocat / AN trying to start astrophoto with my dobson. Servocat is connected to the PC in USB (servocat 3) with one of the ASCOM servocat driver.
Regarding how AN/SC works together you are fully right when you say that you have to do the first two stars alignment with AN manually, BUT once this is done and 1:the PC/software is connected to servocat, with NINA in my case, 2: Argonovis catalog is switched to "from planetarium" slew works very well. I added to my scope a small finder scope with a zwo mono camera declared as the imaging camera in NINA and I can "slew and center" with platesolving to get my target dead center for visual observation.
The next step will be to reach focus with an imaging camera and start real astrophoto. I might change the Argonavis with Nexus DSC pro to avoid doing the initial two stars alignment which means removing the imaging camera and reinstalling it after.
CS, Frédéric
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Re: Argonavis and servocat for astrophoto with NINA
Hi Gary, thank you again for your quick answer.
I am confident now not to be in a hurry to clutch the servocat drives just after the alignement and will not be stressed if the planetarium software sees the scope in a wrong place before clutching after ascom driver connection.
Regarding the altitude sensor I am a fan of the alignment procedure of Scott Tannehill documented in the files and already there when this group was on yahoo (a long time ago ;-).
CS Frédéric
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Re: Argonavis and servocat for astrophoto with NINA
Frederic, Good day sir. My response is inline below... have a great afternoon.
g.
------ Original Message ------
Date 5/20/2025 5:04:45 AM
Subject Re: [ServoCAT] Argonavis and servocat for astrophoto with NINA
Hi Gary,?
I am glad to ear from you. I own two obsession telescopes equiped with your system, one old classic 15 with version 2, and the very first UC22 with version 3. Still working like a charm and I am pushing them in a new era towards automated astrophotography to use them from my light polluted garden. You've developped a system that greatly improved the life of dobson owners. :-)
?
Thank you for your answer. I will switch to Peter's servocat ASCOM driver and compare with the new one.
?
So If I may I have a question for you: according to what you say, when a PC software connected to servocat / AN triggers a GOTO through the connection to servocat, servocat will always ask AN to translate the target coordinates sent as an RA/DEC so an absolute position , sent by the software, in slew commands in AZ and ALT
sent as relative distances from where the scope currently sits as known by the alignment process and subsequently kept track of through the incremental encoders installed on the scope itself , with the corresponding tracking speeds after the slew. Servocat will then apply these commands, with maybe some dialog with AN to declare the GOTO achieved, and the ASCOM driver will report the new position to the PC software and the tracking status.?
yes As a consequence even if I unclutch the servocat motors, move the scope by hand and then reclutch the servocat motors, there is no chance that the PC software triggers a slew that sends the scope in a dangerous zone (above 90) eventhough the PC software was not aware of the manual move so the starting position.
Am I right?
Yes -?tu as réussi!?
because of the incremental encoders the DSC always knows where the scope is - and since they are "affixed" to the scope independent of the ServoCAT it doesn't matter if you disengage/move/re-engage. This is why it is critical that those encoders not slip! The most common cause of slippage would be a torque angle placed on the ALT axis encoder shaft relative to its body causing an internal misalignment of the emitter/detector that indicates a change in speed and direction. The AN has the ability to detect when this occurs in some cases ... however the message it displays when it detects this is proportional to the amount of "missed counts" it sees ... and if this is low (counts) the message is there and gone in an instant and most likely missed by the user. I digress - but just explaining how critical the encoders are to the overall performance of the system is important.
g.
?
?
Thanks again and CS Frédéric
?
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Re: Argonavis and servocat for astrophoto with NINA
Hi Gary,?
I am glad to ear from you. I own two obsession telescopes equiped with your system, one old classic 15 with version 2, and the very first UC22 with version 3. Still working like a charm and I am pushing them in a new era towards automated astrophotography to use them from my light polluted garden. You've developped a system that greatly improved the life of dobson owners. :-)
?
Thank you for your answer. I will switch to Peter's servocat ASCOM driver and compare with the new one.
?
So If I may I have a question for you: according to what you say, when a PC software connected to servocat / AN triggers a GOTO through the connection to servocat, servocat will always ask AN to translate the target coordinates, sent by the software, in slew commands in AZ and ALT, with the corresponding tracking speeds after the slew. Servocat will then apply these commands, with maybe some dialog with AN to declare the GOTO achieved, and the ASCOM driver will report the new position to the PC software and the tracking status. As a consequence even if I unclutch the servocat motors, move the scope by hand and then reclutch the servocat motors, there is no chance that the PC software triggers a slew that sends the scope in a dangerous zone (above 90) eventhough the PC software was not aware of the manual move so the starting position.
Am I right?
?
Thanks again and CS Frédéric
?
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Re: UC22 and Argo Navis for imaging
PHD2 can measure Dec(alt) backlash which would include the whole system so if it's within 10 arc min i assume you could enter the precise measured value in ServoCAT sky.?
?
I only have this issue in altitude, never in azimuth so I could leave azimuth alone.
?
This means autoguiding will not work but I can do 10 seconds unguided. I say 10 seconds, because if I go shorter the frame download time for my DSLR will reduce actual imaging time.
?
Does this mean that the GoTo will "stay" since the precise backlash for the whole system is set?
?
Unfortunately I will not be able to test this before August.
?
If this works then NINA will keep the object within 2-3 arc minutes of the center for the whole night.
?
Or even change object every 1 hour to minimize field rotation then add exposure time in each object next clear night when in the same location in the sky, so you could get lots of Integration time and minimal crop of the corners for each object.
?
/Gabriel?
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Re: Argonavis and servocat for astrophoto with NINA
Frederic,?
Good day sir.?
my comments are shown intermixed? with your note to George Hilios:?
------ Original Message ------
Date 5/19/2025 7:29:26 AM
Subject Re: [ServoCAT] Argonavis and servocat for astrophoto with NINA
[Edited Message Follows]
Hi, here is an update of my first experience.
Episode 1: for VISUAL Use first: remote wireless slew and center to a target with NINA connected to a UC22 Servocat Argonavis with the servocat ascom driver of George Hilios
IT WORKS but the sequence to let it happen has to be followed precisely.
00: I installed a very light guide/finder scope with a zwo camera on top of my UC22 side by side with the telrad finder on the same aluminium tube. The camera is declared as the imaging camera in NINA.
0: the on board PC is not yet connected to servocat. The PC is controled with RemoteDesktop from another one
1: I did a 2 stars alignement with AN as I would to for visual observation
2: when servocat acknowledge I immediately clutch the servocat drive in alt/az
3: connect NINA to the scope right after
4: switch Argonavis catalog to Planetarium (mandatory of course but I forgot several times)
5: and that's it, from now on you just choose a target in NINA or get it from carte du ciel (light on my mele quieter 2) and click on slew and center. When it is done the target is right at the center of the guide scope
6: spend some time to tune the alignment of the guide scope with the optical axis of the main scope as the targets were not visible at first of course. You center the targer in the eyepiece and you take a picture of the guide camera and solve (without centering) it to look at the error distance and you play with the alignement screws of the guide camera holder to center the target on the camera sensor. You need a lot of trials and errors because error in RA/DEC do not translate always in Alt/Az but it is feasible.
Once this is done, it is cool to just wait for the beast to center and discover the target dead center in the eyepiece without spiral search :-).
?
In Episode 2 I will try to attach a main camera to the focuser (my 12v cable was not working yesterday night :-( ) and check if I can reach focus.
?
For George Hilios: Regarding steps 3 and 4, I ended with this conclusion as I understood that the position reported by the servocat driver to NINA after connection is coming from the servocat and not from AN (appears to be different from the real position of the scope if I moved it after the 2 stars alignenment without clutching).?
The ServoCAT has no knowledge of anything related to the sky. ONLY the AN has this info - after all it is what has had a 2 star alignment. ALL positions are from the AN. Note you might want to ensure that the planetarium program is using the same format as the AN. I don't remember which it uses but I think it is Jnow. If CduC were using J2000 or vice versa there would be a discrepancy.?
Here, I have a question for you George: Once I have done 2 stars alignement, AN knows where it is, ALWAYS, even if I move the scope by hand. If I move the scope without clutching the SC motors, SC does not know where it is.?
Again: the ServoCAT never "knows where it is". It receives a relative move value for ALT/AZ from the DSC. It also receives tracking speeds for each axis.?
Later if I clutch the SC motors somewhere, far away from the last star used for 2 stars alignment and trigger a GOTO with AN (SC still not connected to the PC) AN will send to SC the commands with updated info to SC to make it work, and SC has to update its knowledge of where it "looks" to execute the right slew in ALT/AZ and tune the ALT/AZ drive speeds accordingly for tracking.?
Your understanding of the system is completely flipped. First the ServoCAT is always the "master" in comms to the DSC (AN in this case). It asks how far to go, from where the scope currently is to where the AN's current "new" object is ... and it asks what the tracking rate is. There is never a 'command' from the DSC to the ServoCAT. Also planetarium information passes through the ServoCAT because some of that info is for the ServoCAT and some of it is for the DSC. The ServoCAT parses this information taking what it needs and then sending the rest to the DSC. The position values are always sent in whole to the DSC. Also note if you are using a program that has the latest native driver - I believe Sky Safari is the only one - the resolution will be super high - I don't remember for sure but it is well under 1 arcsec. Likewise the original ASCOM driver, Pete Eschman's driver, has this 'high resolution' capability. I don't know if George's supports this or now - I suspect it does but I don't know for sure. The original resolution was more like an arcmin. This has almost no bearing overall in the positioning systems as the error in the scope almost always is greater than an arcmin .... but it will make the planetarium program appear much smoother without the slight 'jerks' of the scope position on the screen.? So if I connect the PC to SC once clutched and resynchronized with AN (with any command from AN to SC), it should work, do you agree? Subsequently, if I have to unclutch the SC motors and move the scope manually, and if I want to restore a proper synchronized status between the scope and the PC, I have to trigger something from AN ( a goto for example) to resynchronize AN and SC before using NINA to slew somewhere with a propre origin position. Am I right??
No.?
Or am complicating too much? Does the servocat ascom driver systematically ask to servocat "where alt/az are we in the sky?" before executing a goto from a software running on the connected PC?
?
Last: I tried George's ASCOM driver on my system and had dropouts. So I went back to the original driver - Peter's. I believe I notified George of this and I think he is testing. Also he is working on a new system - not sure where he is on that. That work is currently private.?
Gary Myers
Thank you for your support, and CS Frédéric
?
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Re: Argonavis and servocat for astrophoto with NINA
Hi, here is an update of my first experience.
Episode 1: for VISUAL Use first: remote wireless slew and center to a target with NINA connected to a UC22 Servocat Argonavis with the servocat ascom driver of George Hilios
IT WORKS but the sequence to let it happen has to be followed precisely.
00: I installed a very light guide/finder scope with a zwo camera on top of my UC22 side by side with the telrad finder on the same aluminium tube. The camera is declared as the imaging camera in NINA.
0: the on board PC is not yet connected to servocat. The PC is controled with RemoteDesktop from another one
1: I did a 2 stars alignement with AN as I would to for visual observation
2: when servocat acknowledge I immediately clutch the servocat drive in alt/az
3: connect NINA to the scope right after
4: switch Argonavis catalog to Planetarium (mandatory of course but I forgot several times)
5: and that's it, from now on you just choose a target in NINA or get it from carte du ciel (light on my mele quieter 2) and click on slew and center. When it is done the target is right at the center of the guide scope
6: spend some time to tune the alignment of the guide scope with the optical axis of the main scope as the targets were not visible at first of course. You center the targer in the eyepiece and you take a picture of the guide camera and solve (without centering) it to look at the error distance and you play with the alignement screws of the guide camera holder to center the target on the camera sensor. You need a lot of trials and errors because error in RA/DEC do not translate always in Alt/Az but it is feasible.
Once this is done, it is cool to just wait for the beast to center and discover the target dead center in the eyepiece without spiral search :-).
?
In Episode 2 I will try to attach a main camera to the focuser (my 12v cable was not working yesterday night :-( ) and check if I can reach focus.
?
For George Hilios: Regarding steps 3 and 4, I ended with this conclusion as I understood that the position reported by the servocat driver to NINA after connection is coming from the servocat and not from AN (appears to be different from the real position of the scope if I moved it after the 2 stars alignenment without clutching). Here, I have a question for you George: Once I have done 2 stars alignement, AN knows where it is, ALWAYS, even if I move the scope by hand. If I move the scope without clutching the SC motors, SC does not know where it is. Later if I clutch the SC motors somewhere, far away from the last star used for 2 stars alignment and trigger a GOTO with AN (SC still not connected to the PC) AN will send to SC the commands with updated info to SC to make it work, and SC has to update its knowledge of where it "looks" to execute the right slew in ALT/AZ and tune the ALT/AZ drive speeds accordingly for tracking. So if I connect the PC to SC once clutched and resynchronized with AN (with any command from AN to SC), it should work, do you agree? Subsequently, if I have to unclutch the SC motors and move the scope manually, and if I want to restore a proper synchronized status between the scope and the PC, I have to trigger something from AN ( a goto for example) to resynchronize AN and SC before using NINA to slew somewhere with a propre origin position. Am I right? Or am complicating too much? Does the servocat ascom driver systematically ask to servocat "where alt/az are we in the sky?" before executing a goto from a software running on the connected PC?
?
Thank you for your support, and CS Frédéric
?
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Re: UC22 and Argo Navis for imaging
Sevan,
Just a clarification of what is going on. The "beep" is actually issued by the ServoCAT to the AN. It is indeed issued when the slew is finished. There is no motion after that, other than tracking which happens immediately, with 2 exceptions.?
1) the backlash is unresolved and indeed it isn't motion but the lack of motion (at the actual point of rotation - the bearing for ALT or the ground board for the AZ. Note that backlash isn't only there in the ServoCAT gearboxes but its also in the mechanics of the scope - which the ServoCAT has no measurement of nor any control over. So there are two sources of lash that need to be resolved. Even if LMIS is in play there still can be backlash seen.?
2) If AutoLOCK is on AND there is backlash there will be drift --- AL will ultimately bring the center point (where it was last left - whether through the results of a GOTO or if moved after that - its center) back to the center. Note that "center" in one persons eyes - depending on the angle they're looking at through the eyepiece isn't?necessarily?center for someone else... so "center" just means where it was left and where the ServoCAT believes that point to be.?
Additionally the update rate from the ServoCAT to the DSC is about 3X a second... so there's no "timing issues".?
Gary Myers ?
------ Original Message ------
Date 5/18/2025 10:52:18 AM
Subject Re: [ServoCAT] UC22 and Argo Navis for imaging
On Fri, May 16, 2025 at 01:12 PM, Gabriel Wiklund wrote:
sometimes after a GoTo/Slew/Recenter the scope slews away as if the backlash has not been cleared
I get that too, from time to time, even with an ArgoNavis.? I have reason to believe it's just a timing issue with ServoCAT talking to the DSCs.? ArgoNavis gives beeps indicating when the slew is "done", after ServoCAT having done the talking to the DSCs thing and recentering.? ServoCAT still moves along with that beep from time to time, and less often, after the beep.? Highly intermittent, and I have found nothing making it more likely than not to happen.? On one night, and one night only, I had it happen a few times, so I unplugged and re-plugged the serial connections on the SC and the AN, and it went away.? That's not enough to say it's related, but maybe perhaps?
?
That this doesn't happen with slews, but only with gotos, is what makes me believe it's a timing issues.? With a slew, there is no talking to the DSCs for refinement.? You could try just letting PHD2 take care of it, which only slews rather than sending gotos, but the issue is that with PHD2 and alt/az, you need to recalibrate every so often as the parallactic angles changes - the camera chips are rotating relative to the sky as the scope tracks.
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Re: UC22 and Argo Navis for imaging
In NINA there is something called "Slew to RA/DEC" or "Slew to ALT/AZ". Does this still mean the Meade Generic driver is causing Nexus to send GoTos since Nexus can't "slew" only?
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Mike
Gabriel Wiklund
Frédéric Ruciak