I've spent multiple nights trying to set up PHD2 guiding with my mount but keep encountering high backlash (>4500ms), which, based on my reading, is quite excessive. Tests Conducted:[*]
Sidereal rate settings:
- Test 1: 0.5x on both RA and DEC
- Test 2: 1.0x on both RA and DEC
- In both cases, calibration results were good.
[*]
Tried different aggressiveness settings:
- DEC: 100 & 0.18 | 20 & 0.18
- RA: 70 & 0.13 | 60 & 0.18
[*]
Enabled backlash compensation in PHD2 with suggested values, but no significant improvement. Observations:- Sometimes the guiding graph is smooth, but at other times, I see sudden spikes or excessive corrections.
- The issue might be caused by the mount itself, but I also suspect a combination of factors such as wind, ground stability, or tripod movement.
Setup Details:I’d appreciate any recommendations or similar experiences from the community!
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With this mount controled by ASIAIR Plus (scope FMA230, ASI294MC Pro, finder and guide camera => ~7 lbs) i can observe sudden spikes. I can auguide between 0,8" total error to 2.5" total error. 90-95% i auguide around 1".
I have changed the tripod to a good video tripod. The mount looks to have less sudden pikes. I need time to confirm this one night experience.
William
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I had a similar very high backlash when I first received my GTi. To fix it I spent some time physically adjusting the DEC and RA backlash screws (instead of playing with the PHD2 settings). The hole to adjust the RA backlash is under the patent number sticker. You'll need a small hex wrench to adjust it. The adjustment screw for the Dec backlash is a bit more difficult to access. You need to remove the cover just above the counterweight bar threaded hole. There are six round-headed hex screws holding it in place. Once you have removed the cover you will see the Dec adjustment screw. I adjusted this to move the worm gear closer to the main gear, thereby decreasing the backlash. Doing this reduced my backlash from about 6000 to 200, as measured by the Guiding Assistant in PHD2, with total RMS down to 0.4 while guiding. While I was at it, I also redistributed some of the excess grease to make sure all gears and cogs were well lubricated. Be careful not to tighten the Dec screw too much - I did this on the first try, and I had sudden spikes due to binding of the gears. I loosened the screw a quarter turn and all was well. Take a look at this video. He removes the cover at 8:50 mins and points to the Dec adjustment screw. https://youtu.be/Ym1_k3aJIkI?feature=shared |
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Mike Dobres:
I had a similar very high backlash when I first received my GTi. To fix it I spent some time physically adjusting the DEC and RA backlash screws (instead of playing with the PHD2 settings). The hole to adjust the RA backlash is under the patent number sticker. You'll need a small hex wrench to adjust it. The adjustment screw for the Dec backlash is a bit more difficult to access. You need to remove the cover just above the counterweight bar threaded hole. There are six round-headed hex screws holding it in place. Once you have removed the cover you will see the Dec adjustment screw. I adjusted this to move the worm gear closer to the main gear, thereby decreasing the backlash. Doing this reduced my backlash from about 6000 to 200, as measured by the Guiding Assistant in PHD2, with total RMS down to 0.4 while guiding. While I was at it, I also redistributed some of the excess grease to make sure all gears and cogs were well lubricated. Be careful not to tighten the Dec screw too much - I did this on the first try, and I had sudden spikes due to binding of the gears. I loosened the screw a quarter turn and all was well. Take a look at this video. He removes the cover at 8:50 mins and points to the Dec adjustment screw. https://youtu.be/Ym1_k3aJIkI?feature=shared 100% agree with Mike. My copy came from factory with a significant backlash both in RA and Dec, and after adjusting, it was improving. Another point: initially I was driving it EQMOD, and I could never set it properly (it is not on the supported devices). I switched to GSS (that supports it) and it improved dramatically. I am not using Asiair.
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thanks guys. I tried following the same video to adjust the DEC and RA backlash. I was worried about not over-tightening. Probably I still have some room for that. How can you measure if it's tight or not?
Also, can you share your current PHD2 settings as a reference? So I can compare it with PHD guidance assistance recommendation.
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Mike Dobres:
I had a similar very high backlash when I first received my GTi. To fix it I spent some time physically adjusting the DEC and RA backlash screws (instead of playing with the PHD2 settings). The hole to adjust the RA backlash is under the patent number sticker. You'll need a small hex wrench to adjust it. The adjustment screw for the Dec backlash is a bit more difficult to access. You need to remove the cover just above the counterweight bar threaded hole. There are six round-headed hex screws holding it in place. Once you have removed the cover you will see the Dec adjustment screw. I adjusted this to move the worm gear closer to the main gear, thereby decreasing the backlash. Doing this reduced my backlash from about 6000 to 200, as measured by the Guiding Assistant in PHD2, with total RMS down to 0.4 while guiding. While I was at it, I also redistributed some of the excess grease to make sure all gears and cogs were well lubricated. Be careful not to tighten the Dec screw too much - I did this on the first try, and I had sudden spikes due to binding of the gears. I loosened the screw a quarter turn and all was well. Take a look at this video. He removes the cover at 8:50 mins and points to the Dec adjustment screw. https://youtu.be/Ym1_k3aJIkI?feature=shared
100% agree with Mike. My copy came from factory with a significant backlash both in RA and Dec, and after adjusting, it was improving.
Another point: initially I was driving it EQMOD, and I could never set it properly (it is not on the supported devices). I switched to GSS (that supports it) and it improved dramatically. I am not using Asiair.
I tried to use GSS, for some reason after a short period of time it crashed. Did you have any issues with GSS?
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Mike Dobres:
I had a similar very high backlash when I first received my GTi. To fix it I spent some time physically adjusting the DEC and RA backlash screws (instead of playing with the PHD2 settings). The hole to adjust the RA backlash is under the patent number sticker. You'll need a small hex wrench to adjust it. The adjustment screw for the Dec backlash is a bit more difficult to access. You need to remove the cover just above the counterweight bar threaded hole. There are six round-headed hex screws holding it in place. Once you have removed the cover you will see the Dec adjustment screw. I adjusted this to move the worm gear closer to the main gear, thereby decreasing the backlash. Doing this reduced my backlash from about 6000 to 200, as measured by the Guiding Assistant in PHD2, with total RMS down to 0.4 while guiding. While I was at it, I also redistributed some of the excess grease to make sure all gears and cogs were well lubricated. Be careful not to tighten the Dec screw too much - I did this on the first try, and I had sudden spikes due to binding of the gears. I loosened the screw a quarter turn and all was well. Take a look at this video. He removes the cover at 8:50 mins and points to the Dec adjustment screw. https://youtu.be/Ym1_k3aJIkI?feature=shared
100% agree with Mike. My copy came from factory with a significant backlash both in RA and Dec, and after adjusting, it was improving.
Another point: initially I was driving it EQMOD, and I could never set it properly (it is not on the supported devices). I switched to GSS (that supports it) and it improved dramatically. I am not using Asiair.
I tried to use GSS, for some reason after a short period of time it crashed. Did you have any issues with GSS?
Nope - GSS has been working reliably since nearly 2 years. Might happen that for some reason your installation got corrupted, I would try and reinstall it. Be careful that GSS has a different go-to behaviour across the meridian compared to EQMOD, that might appear as a bug, but is not. GSS is by design avoiding the flip across the meridian of a certain customizable angle.
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Mike Dobres:
I had a similar very high backlash when I first received my GTi. To fix it I spent some time physically adjusting the DEC and RA backlash screws (instead of playing with the PHD2 settings). The hole to adjust the RA backlash is under the patent number sticker. You'll need a small hex wrench to adjust it. The adjustment screw for the Dec backlash is a bit more difficult to access. You need to remove the cover just above the counterweight bar threaded hole. There are six round-headed hex screws holding it in place. Once you have removed the cover you will see the Dec adjustment screw. I adjusted this to move the worm gear closer to the main gear, thereby decreasing the backlash. Doing this reduced my backlash from about 6000 to 200, as measured by the Guiding Assistant in PHD2, with total RMS down to 0.4 while guiding. While I was at it, I also redistributed some of the excess grease to make sure all gears and cogs were well lubricated. Be careful not to tighten the Dec screw too much - I did this on the first try, and I had sudden spikes due to binding of the gears. I loosened the screw a quarter turn and all was well. Take a look at this video. He removes the cover at 8:50 mins and points to the Dec adjustment screw. https://youtu.be/Ym1_k3aJIkI?feature=shared
100% agree with Mike. My copy came from factory with a significant backlash both in RA and Dec, and after adjusting, it was improving.
Another point: initially I was driving it EQMOD, and I could never set it properly (it is not on the supported devices). I switched to GSS (that supports it) and it improved dramatically. I am not using Asiair.
I tried to use GSS, for some reason after a short period of time it crashed. Did you have any issues with GSS?
Nope - GSS has been working reliably since nearly 2 years. Might happen that for some reason your installation got corrupted, I would try and reinstall it. Be careful that GSS has a different go-to behaviour across the meridian compared to EQMOD, that might appear as a bug, but is not. GSS is by design avoiding the flip across the meridian of a certain customizable angle.
Are you using the default configuration in GSS or made some changes? For example, sidereal rate, etc.
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Are you using the default configuration in GSS or made some changes? For example, sidereal rate, etc. All as default as possible!
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Mike Dobres:
I had a similar very high backlash when I first received my GTi. To fix it I spent some time physically adjusting the DEC and RA backlash screws (instead of playing with the PHD2 settings). The hole to adjust the RA backlash is under the patent number sticker. You'll need a small hex wrench to adjust it. The adjustment screw for the Dec backlash is a bit more difficult to access. You need to remove the cover just above the counterweight bar threaded hole. There are six round-headed hex screws holding it in place. Once you have removed the cover you will see the Dec adjustment screw. I adjusted this to move the worm gear closer to the main gear, thereby decreasing the backlash. Doing this reduced my backlash from about 6000 to 200, as measured by the Guiding Assistant in PHD2, with total RMS down to 0.4 while guiding. While I was at it, I also redistributed some of the excess grease to make sure all gears and cogs were well lubricated. Be careful not to tighten the Dec screw too much - I did this on the first try, and I had sudden spikes due to binding of the gears. I loosened the screw a quarter turn and all was well. Take a look at this video. He removes the cover at 8:50 mins and points to the Dec adjustment screw. https://youtu.be/Ym1_k3aJIkI?feature=shared
100% agree with Mike. My copy came from factory with a significant backlash both in RA and Dec, and after adjusting, it was improving.
Another point: initially I was driving it EQMOD, and I could never set it properly (it is not on the supported devices). I switched to GSS (that supports it) and it improved dramatically. I am not using Asiair.
I tried to use GSS, for some reason after a short period of time it crashed. Did you have any issues with GSS?
Nope - GSS has been working reliably since nearly 2 years. Might happen that for some reason your installation got corrupted, I would try and reinstall it. Be careful that GSS has a different go-to behaviour across the meridian compared to EQMOD, that might appear as a bug, but is not. GSS is by design avoiding the flip across the meridian of a certain customizable angle.
Are you using the default configuration in GSS or made some changes? For example, sidereal rate, etc.
I use the default PHD2 settings. For mount connection I routinely use the Synscann pro app on a Windows PC, connected to the mount via the Skywatcher USB adaptor (ie. no EQMOD or GSS).
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I don't have your mount but rather an EQ6R-Pro. But, I've been running with GSS for about a year, no issues.
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