12 replies to this topic

[Ihtegla Sar]

Fairly new Rowan owner here and first time using a GoTo mount.  Having a problem with GoTo after turning motors off and back on again in Planetarium.  

 

My procedure is to point the mount due south and level and turn it on, then do a two star alignment in Planetarium with two bright well known star as far apart from each other as I can manage.  GoTo works fine for the alignment.  Not completely accurate, but within about five degrees for the first alignment star and within two or three degrees for the second.  Then open Sky Safari using a second phone, so I can use a joystick for slow motion control with Planetarium always open and on top in the first phone.

 

Then GoTo works well enough, putting the target somewhere in the field of view using very low power/wide fields.  

 

But then at some point, I need to turn off motors, such as changing out my diagonal/ADC, when I need to use the Altitude lock to make sure the scope doesn't move when I am swapping heavy accessories.  So I turn off motors in Planetarium, lock altitude, make the swap, unlock altitude and turn motors back on.  Then when I execute a GoTo, the scope slews for a moment and then stops, nowhere near the target.  I am talking some 30 degrees off and in the wrong constellation. Tracking still works, but GoTo goes completely haywire.  Neither Planetarium nor Sky Safari will properly respond to a GoTo command.  Both of them take the scope to a completely different location than where they are supposed to go.

 

This has happened to me a few times now, and every time it is right after turning off the motors for a few minutes and then turning them back on again.  The mount will still track fine, and can be used manually with tracking, but the GoTo goes completely haywire.  I have tried GoTo with both Planetarium and Sky Safari.  Both work fine before turning off the motors and turning them back on again, but both go haywire after turning the motors off and on again.

 

Turning the mount off and on and doing a new star alignment solves the issue (until the next time I turn the motors off) but there must be a way to turn the motors off temporarily without having the GoTo go haywire. 

 

What am I doing wrong here?

Edited by Ihtegla Sar, 08 May 2024 - 11:42 AM.

[photoracer18]

Turning the motors off. That alone will kill the go-to alignment on just about any go-to mount unless is has relative encoders.  Leave the motors on so their built in encoders will know where you moved it if it moves at all during your procedure. In general the motors have to stay on on a go-to mount to maintain the current alignment. Some go-to mounts only count pulses from the stepper motors and don't have real encoders so turning the motors off causing them to lose their alignment settings.

Edited by photoracer18, 08 May 2024 - 12:18 PM.

[swsantos]

I believe the AZ100 has encoders such that the motors can be turned off and on without losing alignment so I don't think its that. I have done that without issue, but I have never used two different devices to access the mount at the same time. How about running SkySafari from the same device that you initially connected to and aligned with with the planetarium??

[Ihtegla Sar]

I believe the AZ100 has encoders such that the motors can be turned off and on without losing alignment so I don't think its that. I have done that without issue, but I have never used two different devices to access the mount at the same time. How about running SkySafari from the same device that you initially connected to and aligned with with the planetarium??

If I recall, the first time I had this problem, that is what I was doing, with SkySafari and Planetarium both on the same phone and switching back and forth when I want to use the joystick.  But that was a few weeks ago, so I could be remembering it wrong. It has been very cloudy lately, so the first time I had a chance to use the mount in a few weeks was last night.

 

I am going out of town tonight but should have some clear weather later in the week to try again, using just one device.  I may try with just Planetarium and not even connect to Sky Safari, since that would eliminate other variables and see what happens.

 

I like Planetarium and once they fix the WDS, I may end up just using Planetarium, but in the current version of the firmware I am using (1.2) WDS is broken.

[aranelchan]

I admit that when I'm using SkySafari and need to change eyepieces, I don't switch to the Rowan planetarium to turn off the motors and engage the altitude brake, but rather I tighten the altitude clutch then keep one hand lightly on the pan/tilt handle while swapping eyepieces with the other hand. Perhaps a bit naughty, but Derek did point out that even the altitude brake is not absolutely foolproof.

 

Turning the motors off. That alone will kill the go-to alignment on just about any go-to mount unless is has relative encoders.  Leave the motors on so their built in encoders will know where you moved it if it moves at all during your procedure. In general the motors have to stay on on a go-to mount to maintain the current alignment.

Did you mean absolute encoders? I believe the AZ100 has relative encoders, but as the motors can be turned on/off separately from the mount itself, the encoders continue to operate even when the motors are turned off via the Rowan planetarium. The AZ100 manual recommends turning off motors before engaging the altitude brake, in contradiction to your implied recommendation that the motors remain turned on at all times during use of the mount, so I would expect the AZ100 to be an exception to your general rule.

[weis14]

I don't think I've ever turned off the AZ100 motors when changing eyepieces.  Rather, I just hold the OTA in place with my free hand.  I keep the clutches loose enough that I can push the scope around without shutting off the motors in regular operation, so holding the OTA steady makes no difference.  That is one of the real benefits of the AZ100 because you can push the mount to a new target and have the tracking resume flawlessly once you've pushed it there. 

 

With this approach, if I'm connected to SkySafari, I never have the AZ100 planetarium open at the same time.

[Ihtegla Sar]

Just to be clear, I wasn't just changing eyepieces. I don't bother with the altitude break just to change eyepieces.

I was removing a rather heavy 2" Zeiss prism diagonal and replacing it with an even heavier ADC/diagonal combination.

But there are other reasons for temporarily shutting off the motors, such as using the manual slow motion controls.

Based on what I read about the mount, I was under the impression that one could temporarily turn off the motors and the mount would still keep its alignment. It still tracks fine even after turning the motors off and on. And you can always move the mount manually with the pan handle without affecting alignment or the ability to do an accurate GoTo. Based on all that I guess I was kind of surprised when temporarily turning the motors off messed up GoTo (but not tracking).

Would it be possible for someone who owns the AZ100 with motors to try turning the motors off and on again and see if a GoTo will still work? Maybe at the end of a session when you won't need to re-align? Would be good to know if this is a feature common to all AZ100s, or if its just me.

Edited by Ihtegla Sar, 08 May 2024 - 03:37 PM.

[Ihtegla Sar]

I don't think I've ever turned off the AZ100 motors when changing eyepieces. Rather, I just hold the OTA in place with my free hand. I keep the clutches loose enough that I can push the scope around without shutting off the motors in regular operation, so holding the OTA steady makes no difference. That is one of the real benefits of the AZ100 because you can push the mount to a new target and have the tracking resume flawlessly once you've pushed it there.

With this approach, if I'm connected to SkySafari, I never have the AZ100 planetarium open at the same time.

What do you do for slow motion control? I can't seem to use the screen controls in Sky Safari very well, so I need Planetarium open for the joystick control.

But there is currently no double star database in Planetarium, so I need Sky Safari since I am primarily a double star observer this time of year.

So, I was constantly switching back and forth, until I realized I had an old phone that still worked for WiFi and I could just keep both open.

[Dek Rowan]

Just to be clear, I wasn't just changing eyepieces. I don't bother with the altitude break just to change eyepieces.

I was removing a rather heavy 2" Zeiss prism diagonal and replacing it with an even heavier ADC/diagonal combination.

But there are other reasons for temporarily shutting off the motors, such as using the manual slow motion controls.

Based on what I read about the mount, I was under the impression that one could temporarily turn off the motors and the mount would still keep its alignment. It still tracks fine even after turning the motors off and on. And you can always move the mount manually with the pan handle without affecting alignment or the ability to do an accurate GoTo. Based on all that I guess I was kind of surprised when temporarily turning the motors off messed up GoTo (but not tracking).

Would it be possible for someone who owns the AZ100 with motors to try turning the motors off and on again and see if a GoTo will still work? Maybe at the end of a session when you won't need to re-align? Would be good to know if this is a feature common to all AZ100s, or if its just me.

Hello I Sar,

 

Alignment should be kept when turning the motors on and off. The encoders are mounted on the axis shafts and remain powered at all times.

Try with just the Rowan Planetarium connected to eliminate a SF conflict.

What power supply are you using. Random problems like this can be associated to a under rated PSU and the issue you are experiencing is not normal.

 

The chosen alignment stars should be roughly 90 degrees apart in AZ and about 30 degrees in Alt, there or thereabouts.

Remember when adding a third alignment star, the first is deleted and replaced by the second, so ensure the third alignment star is separated from the second. 

The alignment star buffer is first in first out. 

 

ATB

Derek.

[Ihtegla Sar]

Hello I Sar,

Alignment should be kept when turning the motors on and off. The encoders are mounted on the axis shafts and remain powered at all times.
Try with just the Rowan Planetarium connected to eliminate a SF conflict.
What power supply are you using. Random problems like this can be associated to a under rated PSU and the issue you are experiencing is not normal.

The chosen alignment stars should be roughly 90 degrees apart in AZ and about 30 degrees in Alt, there or thereabouts.
Remember when adding a third alignment star, the first is deleted and replaced by the second, so ensure the third alignment star is separated from the second.
The alignment star buffer is first in first out.

ATB
Derek.

Thanks Derek. Good to know this isn't normally how it's supposed to work.

The PSU I am using is a 12 volt, 6 amp brick style AC to DC power converter plugged into AC power. There are no other devices plugged into the PSU.

The alignment stars I used are Albireo and Izar.

It will be a couple days before I am able to try again but I will try again with just Planetarium and see if the issue persists.

[weis14]

What do you do for slow motion control? I can't seem to use the screen controls in Sky Safari very well, so I need Planetarium open for the joystick control.

But there is currently no double star database in Planetarium, so I need Sky Safari since I am primarily a double star observer this time of year.

So, I was constantly switching back and forth, until I realized I had an old phone that still worked for WiFi and I could just keep both open.

For slow motion control and fine corrections, I use my hand on the diagonal of the scope, much like I would with a dob or any number of other alt-az mounts over the years.  Even at 200x or more, that has worked fine for me due to how smooth the AZ100 is.  Before I had the motor kit, I used the slow motion controls for tracking, but even then, target acquisition was done by pushing the scope where it needed to be.  Many nights I'm using thick gloves, so it just became a habit to push the scope were I wanted it after aligning it.  Usually I order an actual go-to only for alignment.  

 

If I'm looking for double stars, I typically use SkySafari with the push-to method above.  I've also been meaning to order the serial cable from Rowan to start using my Nexus DSC, but I'm also intrigued by the Rowan controller that is in development and might just wait for that to become available.  

[Ihtegla Sar]

For slow motion control and fine corrections, I use my hand on the diagonal of the scope, much like I would with a dob or any number of other alt-az mounts over the years. Even at 200x or more, that has worked fine for me due to how smooth the AZ100 is. Before I had the motor kit, I used the slow motion controls for tracking, but even then, target acquisition was done by pushing the scope where it needed to be. Many nights I'm using thick gloves, so it just became a habit to push the scope were I wanted it after aligning it. Usually I order an actual go-to only for alignment.

If I'm looking for double stars, I typically use SkySafari with the push-to method above. I've also been meaning to order the serial cable from Rowan to start using my Nexus DSC, but I'm also intrigued by the Rowan controller that is in development and might just wait for that to become available.

I'm not good enough for hand control at high power on anything other than my Obsession, and there I am using big widefield eyepieces. 12mm ES 92 and 9mm ES 120mm. The Rowan is very smooth and with the YAB it balances very well but I tend to overshoot when trying to center with the panhandle at 200x. But I am typically using 45 to 52 AFOV eyepieces with it and one of my two scopes on my AZ100 is 3000mm focal length and weighs 40 pounds, so I am pushing right up to the weight limit. The joystick control works very well for me.

[Ihtegla Sar]

I wanted to report back that I tested last night and with just Planetarium running the mount continued accurate GoTo movements after turning the motors off and on again several times, even moving the mount with the motors off.  So then I fired up Sky Safari and used it for some GoTos, which worked fine.  So, then I turned the motors off and on again in Planetarium, and still the GoTos worked fine, with both Planetarium and Sky Safari up at the same time (on two different devices).

 

I am not sure what happened before.  The GoTo went haywire after turning motors off and on again, but that appears to have been coincidental, since now the GoTo works fine after turning motors off and on.  I am not sure why the GoTo went haywire before.  Seems to be working fine now.  I will keep an eye on it and see if it gives me any further issues.  Thanks all.