Back to forums

Star Adventurer not holding polar alignment

Sky-Watcher Star Adventurer Star Tracker Polar Alignment Troubleshooting
10 replies•367 views
Franco Grimoldi avatar
Franco Grimoldi avatar
Hi all!

After one year of flawless use, I'm starting to have trouble with my Star Adventurer. On two of my last four imaging sessions, it's not holding polar alignment. I don't know what could be causing this, I follow the same workflow each time.

Yesterday I failed three times in a row to get it to work. This is my southern workflow:
. Set and level the tripod, forcing the legs to dig into the grass and making sure it doesn't move.
. Loosen the equatorial wedge from below to start looking for the Octans asterism. Once it's within the finder's view, I lock the wedge.
. Loosen the RA clutch to make the Octans asterism show the same orientation in the finder as in "real life".
. Adjust the wedge's AZ/Alt until I get the asterism's stars inside their respective circles in the finder.
. Lock AZ and Alt.
. Unlock RA and Dec to start star-hoping for my target. Once framed, I zero the RA setting circle (around the polar finder eyepiece) to have my target's position marked.
. I re-check polar alignment by rotating the RA axis until the asterism lines up with the finder: it's always off. When it fails, it's so off that I get star trails on 30" exposures.

This is the same procedure I always followed without issues. On my last successful session, last Saturday night, I was able to get good 2-minute exposures.

This is the type of tracking error I consistently get:

30" exposure - 100% magnification

Any troubleshooting tips would be very appreciated. It's extremely frustrating to be freezing outside wasting some of the few clear nights we've had so far this season.

Thanks!
Well Written Helpful Engaging
TiffsAndAstro avatar
TiffsAndAstro avatar
Franco Grimoldi:
Hi all!

After one year of flawless use, I'm starting to have trouble with my Star Adventurer. On two of my last four imaging sessions, it's not holding polar alignment. I don't know what could be causing this, I follow the same workflow each time.

Yesterday I failed three times in a row to get it to work. This is my southern workflow:
. Set and level the tripod, forcing the legs to dig into the grass and making sure it doesn't move.
. Loosen the equatorial wedge from below to start looking for the Octans asterism. Once it's within the finder's view, I lock the wedge.
. Loosen the RA clutch to make the Octans asterism show the same orientation in the finder as in "real life".
. Adjust the wedge's AZ/Alt until I get the asterism's stars inside their respective circles in the finder.
. Lock AZ and Alt.
. Unlock RA and Dec to start star-hoping for my target. Once framed, I zero the RA setting circle (around the polar finder eyepiece) to have my target's position marked.
. I re-check polar alignment by rotating the RA axis until the asterism lines up with the finder: it's always off. When it fails, it's so off that I get star trails on 30" exposures.

This is the same procedure I always followed without issues. On my last successful session, last Saturday night, I was able to get good 2-minute exposures.

This is the type of tracking error I consistently get:

30" exposure - 100% magnification

Any troubleshooting tips would be very appreciated. It's extremely frustrating to be freezing outside wasting some of the few clear nights we've had so far this season.

Thanks!


my sw SA GTi is rickety af. My guesses...
1 photo tripod leg is not locked or broken and slides up slowly over time
2 one or more legs are sinking
3 tighten the lock screws a fair bit before trying pa
4 my alt bolt always has a big dead zone near perfect polar alignment. I try and get it so it just re engages.
5 run 3ppa more than once

My set up last 3 months with the GTi and Nina is as follows.
Plonk tripod and mount near the marks I hide on patio
Run 3ppa get it roughly correct by shuffling tripod legs around and then alt/az bolts to get under 60", then run it again and get under 10" pretty quick
then I don't breathe near it
Rodrigo Roesch avatar
Rodrigo Roesch avatar
Hi
Just wondering if your batteries are good or the camera is sliding a bit. I have had similar issues when using some tripod heads that can't be tighten well
Guillermo (Guy) Yanez avatar
Guillermo (Guy) Yanez avatar
I presume this is the classic or 2i SA. In my experience, what you described will provide only a rough polar alignment. I would try using the three-point polar alignment routine in NINA on manual mount mode, which works very well. I would also try to keep the exposures under 120 seconds, given it will not correct on DEC.Even if you keep the tripod legs with stakes on the ground, grass or dirt is never stable enough. Try using three bricks or a solid base for your tripod. I would also double-check if the tripod legs are secured properly. I have even seen Manfrottos having small movements during an imaging session, which will have implications on the orientation of the mount.
Helpful Insightful Respectful Concise
Franco Grimoldi avatar
Franco Grimoldi avatar
This is my setup:

I don't use batteries. I power the mount and camera with a USB brick.

The one thing that I recently changed is the red dovetail clamp but, if anything, it fixed a DEC balance issue I used to have.

Regarding the equatorial wedge, I don't like at all the altitude adjustment system, but still, I don't understand why would it suddenly start to misbehave...

I might have clear skies tomorrow night, my plan is to do test images without rotating the RA axis after polar alignment. If I get good tracking before moving and bad tracking after... I might be onto something....
Franco Grimoldi avatar
Franco Grimoldi avatar
Guillermo (Guy) Yanez:
I presume this is the classic or 2i SA. In my experience, what you described will provide only a rough polar alignment. I would try using the three-point polar alignment routine in NINA on manual mount mode, which works very well. I would also try to keep the exposures under 120 seconds, given it will not correct on DEC.Even if you keep the tripod legs with stakes on the ground, grass or dirt is never stable enough. Try using three bricks or a solid base for your tripod. I would also double-check if the tripod legs are secured properly. I have even seen Manfrottos having small movements during an imaging session, which will have implications on the orientation of the mount.

So... The polar alignment routine never failed before for 30" subs with the Rokinon 135mm and 3.91um pixels... And I got decent tracking on 90" and 120" subs before:

120" crop at 100%.

There's no NINA or any automation here, just the mount and the camera for the time being... By the way, I believe that the "manual" polar alignment can be much better for us southerners being that we have to get 3-4 stars within their respective circles instead of relying on getting Polaris on a somehow generic spot in the finder reticle.

I think you might be right regarding the grass, unfortunately I don't have a good solution available. What makes me doubt is that I got two really good nights and two aborted ones from the same spot.... I'll see tomorrow once I get a new session going.
Franco Grimoldi avatar
Franco Grimoldi avatar
UPDATE:


121" exposure from a few hours ago. Crop at 100%.

Workflow changes:
. Set up and leveled the tripod during daylight.
. Set the altitude on polar alignment using always "up" movements as the knob tends to stay put better that way. If I needed to go down, I went below the target and then came back up to land just on the spot. It felt similar to tuning a guitar string always increasing the tension, never lowering it to get in tune.

That was it. I re-checked the PA after framing, it was just a tiny bit off but nothing compared to my previous night.

The hit rate doesn't seem to be very promising, though. I think that the unguided Sky Adventurer starts to show its inconsistencies shooting 2 minutes subs at 6.2"/pixel resolution. I still need to throw everything into WBPP and see what comes out but the results look very promising.
Helpful
Peter Graf avatar
Peter Graf avatar
I also can confirm that behavior with my copy of the Star Adventurer. The equatorial wedge is not really precise, and I ended up first tightening the altitude with rough alignment, and then doing the fine alignment always "up". Same procedure: if too far, going back below, then up again.
Tightening the altitude after PA always slightly worsened alignment.

Some people, I heard, are also using other wedges than the stock one, but these are way more expensive.
Helpful Concise
Franco Grimoldi avatar
Franco Grimoldi avatar
Well, this is embarrassing:

121" exposure from tonight.

Today I spent three hours troubleshooting my tracking issues, to finally get to the actual root cause: IT WAS ME 🙋‍♂️.

I was about to give up, nothing seemed to work, then I decided to follow the advice from @Guillermo (Guy) Yanez : I ran NINA for the first time. I used my desktop PC without any link or connection to the mount or camera. I installed ASTAP and configured the "fake" NINA camera that gets images from a folder. With that setup, I was able to run the three-point polar alignment... which showed that I was over 10 degrees off to the west 🤦‍♂️🤦‍♂️🤦‍♂️🤦‍♂️🤦‍♂️🤦‍♂️.

It turns out that the Octans asterism is almost invisible under a Bortle 7-8 sky with a 70+% illuminated moon and I was pointing at the wrong set of stars. It wasn't that the mount was losing polar alignment... it was that it wasn't pointing to the south celestial pole to begin with and, as expected, the wrong asterism kept escaping from the polar finder.

This also explains why I just started failing like this: all my previous imaging sessions were done from Bortle 4 or better skies, in which the visual PA takes less than 5'.

In addition to the polar alignment headaches, the tracking is proving to be not consistent enough to deliver a high percentage of good shots, it's hit n' miss, mostly missing. Given that I'm trying to start doing multiple-nights imaging sessions, lowering the exposure time really doesn't help (I already have close to 700 subs on this subject), I need to start guiding.

Having said this, I'm now researching for a good mini-PC to run NINA and start computerizing my setup, thinking about first getting a guider and then, finally making the jump to a real dedicated astro-camera.

Thanks all for reading and the good advice, you are an awesome community 🙌.
Well Written Helpful Insightful Engaging
Pariah avatar
Pariah avatar
I'd upgrade the star adventurer to a half decent go to mount first. My SW SA2 was absolute junk, pot metal sloppy tolerance wobbly rubbish. Best thing I ever did was to sell it and get a goto mount.
Franco Grimoldi avatar
Franco Grimoldi avatar
I'd upgrade the star adventurer to a half decent go to mount first. My SW SA2 was absolute junk, pot metal sloppy tolerance wobbly rubbish. Best thing I ever did was to sell it and get a goto mount.

I find it to be half decent already, I'm very happy with the results I've been having so far. The worst part of my setup proved to be myself. Until I outgrow the mount, it's staying. Yesterday I came very close to deciding getting a new mount, but now I have that budget available for other parts that also need upgrading, starting with a mini-PC to run NINA.