Re: G11G Gemini2 PHD2 autoguiding calibration jumps by more than 20px during east calibration
I don't see anything bad in your video. After the west steps (usually 12 on default settings) the east steps are quite abrupt and fast, in just three should get the star to the original position.? Then it starts clearing backlash steps at which your video ends. Can you provide the calibration plot ?? More important, after calibration is there any warnings from PHD2 ? And last but not least, how is your guiding ??
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Regards,
Daniel
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First visual use of my G11G
I've had the G11G for about a year now.? Got it mainly for back yard imaging.? ?Last weekend the club had an outreach event so we brought the G11G and dusted off our old C11 and used it to share some views with the public.? A few observations:
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- It handles the C11 way better than the EQ-G mount I bought the scope with.? That is the predecessor to the current Eq6 class mounts.? I got a lot of good use out of that mount, but this one was much more confident with that load.?
- Go-tos were much more accurrate, once I got a model built.? ? There was nothing that was outside of the eyepeice that had about a half degree field of view.?
- Model building for the first time was...interesting.? ?I should have read up on it.? It took me about 4 tries to get it to work.? The first one everything was way off the initial go-to, and slewing over before syncing still resulted in a bad model.? The second time, for some reason still unkown to me, it selected 3 stars all i Cassiopea.? I knew that wasn't going to work.? It was after that time that I figured out I still had the Lat/Long from our recent trip to an out of state star party.? I fixed that, and it fixed the initial go-to pretty well.? Then on the next try I figured out I could hit the East or West button again before go-to and it would select a different star to go to.? ?That was when I nailed a good alignment - I don't have a ton of star names memorized so I could pick ones easy for me to find!? ?3 stars on each side.? ?Did a great job all night after that.?
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I really enjoyed it for visual use.? Been happy with the imaging, though I need to improve guiding a bit for my 130mm refractor.? ?But I think its just a matter of finding the time to mess with some settings a bit.??
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Was good to be out there in visual mode!? And not pushing around a big dob, not that I'm complaining about having a nice big dob.??
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Brian
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Re: G11G Gemini2 PHD2 autoguiding calibration jumps by more than 20px during east calibration
On Tue, Aug 13, 2024 at 02:28 AM, Nikul Suthar wrote:
any ideas
In the video, the mount moves as directed during recalibration, although there is a delay in image capture. The question is whether the mount can move 25 pixels in the roughly one second of exposure and processing time. The software appears to reposition to the guide star with high precision. From this, I deduce that the mount does move the specified distance within that timeframe upon command, and it does so with considerable accuracy.
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Re: G11G Gemini2 PHD2 autoguiding calibration jumps by more than 20px during east calibration
Hi Paul,
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I'll try after keeping a little more backlash in RA & in DEC. I'll make sure that the clutches are not too tight. As such the autoguiding for East pointing West is fairly good with sub arc second total at 1384 mm focal length. Let me try these out and get back.
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Thanks,
Nikul
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Re: G11G Gemini2 PHD2 autoguiding calibration jumps by more than 20px during east calibration
Hi Nikul,
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Are you sure the jump is in RA and not in DEC? Backlash in RA isn't normally an issue, since during tracking/guiding the mount doesn't reverses direction in RA. The opposite of backlash is stiction, something that is caused by worm/gear being too tight. This allows for energy to be built up during normal movement and to be released suddenly at certain times. Leaving a little backlash in the worm/gear is important to avoid this. Other places to look:
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- The oldham coupler may be loose (set screw needs to be tightened)
- The worm isn't tight enough between the two bearings that hold it, allowing the worm to move between them (not sure how the OPWB handled it)
Regards,
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?-Paul
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On Tue, Aug 13, 2024 at 02:28 AM, Nikul Suthar wrote:
Hello All,
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I've older version of G11G with OPWB (Prior to Spring loaded worm gear). I'm getting a sudden jump in PHD2 autoguiding calibration process when after moving by 25px in the west and as soon as it tries to move back towards east direction. This can be seen in my below uploaded video sharp at 31 seconds:
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This calibration is closer to Meridian and East pointing West. But same observation is during calibration closer to Meridian and West pointing to East. I just re-greased the spur gears and the worm-wormwheel assembly with Liqui Moly in both RA & Dec axes. I then adjusted backlash to be minimum both in RA & Dec axes. Regardless of minimal backlash adjustment or not this behavior keeps repeating. I fairly balanced my Celestron C9.25 OTA with 1384 focal length after 0.63 reducer. I'm doing off axis guiding with this same focal length and have configured PHD2 as well with it. I made sure that the Dec motors are tightly screwed in.
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Anybody has any ideas on why this is happening then that would be really helpful. I can provide more details if anybody asks and can try suggestions the next night I get to imaging.
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Thanks,
Nikul
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Re: Goto the Moon way off
The Gemini II includes an app for polar alignment. It¡¯s called ¡®PAC¡¯ or ¡®Polar Axis Correction¡¯ or ¡®Polar Align Correction¡¯.?
It works by starting with a rough polar alignment, then doing a sky model (3 stars west plus 1 star east of the meridian, for example).
Once you¡¯ve done the sky model you then do a goto a bright star. Gemini II will then offset the scope to where the mount should be pointing if the polar axis was properly aligned. Then you carefully adjust the mount¡¯s Alt and Az knobs to re-center the star. This re-positions the mount¡¯s polar axis so that it¡¯s more closely aligned to the NCP.
Scott describes the process in this video linked below. The video is a bit simplified. He just uses the first prompted star for each goto, whereas you can pick any star in the list as an alignment star. But the process he describes works to greatly improve polar alignment.
The key point is that *you don¡¯t need to see Polaris* in order to get the mount polar aligned.
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https://youtu.be/yYiHldJ5CKA?si=KTA5sHgEE1nmlTzb
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G11G Gemini2 PHD2 autoguiding calibration jumps by more than 20px during east calibration
Hello All,
?
I've older version of G11G with OPWB (Prior to Spring loaded worm gear). I'm getting a sudden jump in PHD2 autoguiding calibration process when after moving by 25px in the west and as soon as it tries to move back towards east direction. This can be seen in my below uploaded video sharp at 31 seconds:
?
?
This calibration is closer to Meridian and East pointing West. But same observation is during calibration closer to Meridian and West pointing to East. I just re-greased the spur gears and the worm-wormwheel assembly with Liqui Moly in both RA & Dec axes. I then adjusted backlash to be minimum both in RA & Dec axes. Regardless of minimal backlash adjustment or not this behavior keeps repeating. I fairly balanced my Celestron C9.25 OTA with 1384 focal length after 0.63 reducer. I'm doing off axis guiding with this same focal length and have configured PHD2 as well with it. I made sure that the Dec motors are tightly screwed in.
?
Anybody has any ideas on why this is happening then that would be really helpful. I can provide more details if anybody asks and can try suggestions the next night I get to imaging.
?
Thanks,
Nikul
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Re: New G11 + ASIair guiding issues
Is your calibration OK?? Does it make too much backslash clearing steps ???? If you post the PHD2 log file may be some other guy here with more experience can look at your results.
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Regards,
Daniel
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Re: Goto the Moon way off
Thanks all
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The clouds have beaten me again - but as stated the scope is going? in the right direction.
Re Sharpcap - I never knew - and I've printed out the manual. :(
I'll update asiair tomorrow - and read up on it.
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Re: Goto the Moon way off
NINA's 3-point polar alignment is good.
In the meantime, of course do the obvious:
Set up your mount with the polar axis pointing true north (not magnetic north) as near as you can get it.? Look up the difference between true and magnetic north.
Set up your mount with the altitude of the polar axis equal to your latitude (it is labeled).
Best of luck to you!
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Re: Goto the Moon way off
On Sun, Aug 11, 2024 at 01:46 PM, Dave Elson wrote:
I'n not polar aligning (yet).
I have no view of north due to the house.
I will see how close I am to the moon and make adjustments (I hope) using the altitude and azimuth adjusters.
I have downloaded but not used Sharpcap (and earlier NINA) and I've also a used Asiair, again unused by me yet.
Much of the software is confusing to start - I just have? to start? using it and make my mistakes early.
A little bit smoky today - don't know if I'll be out.
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This confirms that as I posted the only way to improve your initial GOTOs will be to get a good polar alignment. You still need to build a model once you have a good PA to ensure GOTOs are accurate on both sides of the meridian.
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Some notes:
1#? SharpCap Pro 4.1 is not capable of polar alignment without a clear line of sight to the NCP.?
2#? NINA is All-Sky PA capable (no NCP line of sight) but I have not used it.
3#? ZWO ASIAIR Plus is All-Sky PA capable (no NCP line of sight) I use it every time I observe or image, it works very well.?
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IME the ASIAIR Plus is probably your best bet and is very easy to use. I can get my total RMS error under 10 arc seconds but usually just stop anywhere under 30 arcseconds. GOTOs are exact in the eyepiece of the Takahashi FC-100DL that rides side-by-side and is co-aligned with the bespoke Parallax/AT130 f/6 SDT imaging optic taking 2 or 3 plate solves to verify centering for imaging. Once the ASIAIR Plus has done an All-Sky PA the Losmandy G11G centers objects anywhere in the sky.? ?
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--
Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Re: Goto the Moon way off
I'n not polar aligning (yet).
I have no view of north due to the house.
I will see how close I am to the moon and make adjustments (I hope) using the altitude and azimuth adjusters.
I have downloaded but not used Sharpcap (and earlier NINA) and I've also a used Asiair, again unused by me yet.
Much of the software is confusing to start - I just have? to start? using it and make my mistakes early.
A little bit smoky today - don't know if I'll be out.
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Re: Goto the Moon way off
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As I asked above, how are you doing your polar alignment? This is probably the most likely issue at this point because the mount is now pointing in the general direction.
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The only way you are going to get your initial GOTO more accurate at this point is to get an excellent polar alignment before building (a 2 or more star aligned) model so the Gemini knows where it is pointed. The rest of this work is probably a waste of time.??
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--
Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Re: Goto the Moon way off
On Sat, Aug 10, 2024 at 06:44 PM, Dave Elson wrote:
at least it was in the right direction
After successfully initializing the site CWD, you can physically adjust or check the declination of a G11 with the Dec saddle spirit level. When positioned at Zenith, the Dec spirit level should be horizontal, assuming the OTA is vertically aligned at zenith and the saddle is set by Gemini to align with the Zenith at the Site Latitude. If it's not level, you can make adjustments using the Altitude knob. To view the level from below, a small mirror can be utilized.
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Re: Goto the Moon way off
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My standard way of accessing and updating the Gemini 2 has always been over Ethernet using the web UI and FTP updated files to the SD card. Tom told me how to do it back in the day and being a computer person this made a lot of sense to me until the GFU was perfected. GFU has spoiled me.??
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--
Chip Louie Chief Daydreamer Imagination Hardware?
Astrospheric Forecast - South Pasadena, CA?
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Re: Goto the Moon way off
Well done Paul
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cheers
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Brendan
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Re: Goto the Moon way off
Thanks Way back.
Yes I'll reread the docs. I just tried the moon again and the scope went to CWD (on command), then moon? (although I couldn't see it - at least it was in the right direction) and then went home on command.
I'd try once more but the Mighty Seahawks are on soon. :)
Cheers.
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Re: Goto the Moon way off
Dave,
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I'd just use the PC browser you got working.? The HC cannot set the Sites.? You need to do that through the Gemini-2 LAN Server Browser Pages.? The one titled "Site/Time".? There exists five saved Sites, the Active Site and the four saved Sites.? You can make a Saved site the Active site or edit a field and the Active definition becomes unique.?
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This information stores to non-volatile Ram.? If you want to save and restore the definition you must remember to save all your settings with the HC using Menu->System->Store which stores to the SD Card.
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Esoterically, you can access this file using FTP (File Transfer Protocall) using the Windows File Explorer program and your Ethernet connection.? Also documented within with some searching.
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Re: Goto the Moon way off
On Sat, Aug 10, 2024 at 03:26 PM, Chip Louie wrote:
Does this save every settable value? Maybe I have been overlooking something handy!
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All settings within Gemini.NET are stored in the profile. PEC data is optional, and you can select if you want to store it or not.
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Re: Goto the Moon way off
Well - I tried it today with a? cold start and although the moon wasn't up - it correctly found the sun. I say "found" - it at least got the right direction
Switched off and on again and had to restore CWD position and Home position and while it's too early to say definitely - it found the Sun again - went to CWD and Home positions.
I've switched off - and I'll wait and try to moon when up.
So as I say it's too early to be definite but I appreciate the help.
I have to? look at sites again.
I think I read that site "0" will always be Hollywood.
I seem to show
Spokane (Active)
Spokane
Phoenix
Berlin
Australia
I confuse easy I admit - but we did an overide of Hollywood.
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Paul Kanevsky
Chip Louie