Re: RA axis movement or wiggle
I can't speak to the AP design
On Sun, Aug 28, 2022 at 5:25 AM HenkSB < haling@...> wrote: On Fri, Aug 26, 2022 at 09:06 PM, Brian Valente wrote:
Michael has it correct, you are likely seeing the effects of the spring-loaded worm. It's not a good idea to try to zero it out, that's not how the spring-loaded worms work
?
Roland Christen from AP did a nice writeup on this recently (AP mounts have spring-loaded worms as well) which may make for good background reading on this topic:
"why is a mount springy"
?
It looks like the AP SLW works different than the Losmandy one.? They have a backoff screw to limit the outward movement of the worm whereas the Losmandy SLW has a backoff screw to limit the inward movement of the worm.? The idea with AP is that the spring pressure is kept low, appropriate for tracking but not? for slewing whereas with Losmandy it is higher to handle the pressure required for slewing and is mostly aimed at preventing bind-up while allowing tighter settings to minimize backlash.? Is that a correct assessment?
-- Brian?
Brian Valente astro portfolio? portfolio astrobin?
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Re: RA axis movement or wiggle
On Fri, Aug 26, 2022 at 09:06 PM, Brian Valente wrote:
Michael has it correct, you are likely seeing the effects of the spring-loaded worm. It's not a good idea to try to zero it out, that's not how the spring-loaded worms work
?
Roland Christen from AP did a nice writeup on this recently (AP mounts have spring-loaded worms as well) which may make for good background reading on this topic:
"why is a mount springy"
?
It looks like the AP SLW works different than the Losmandy one.? They have a backoff screw to limit the outward movement of the worm whereas the Losmandy SLW has a backoff screw to limit the inward movement of the worm.? The idea with AP is that the spring pressure is kept low, appropriate for tracking but not? for slewing whereas with Losmandy it is higher to handle the pressure required for slewing and is mostly aimed at preventing bind-up while allowing tighter settings to minimize backlash.? Is that a correct assessment?
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Re: Resetting spring-loaded worm
Daniel,
Thanks for posting. Captured over 2.5 hrs, great job!
You might want to consider toning down your dither. 10 arcsec dither seems mighty excessive! There are those here who can make a more insightfully recommendation based on your camera pixel size and focal length. You really ought to aim for a few pixels not the other side of the universe.?
On the positive side, recovery after dither is excellent. A+?
Your PE is 8.3" p-p, which is in the range for an unmodded mount. But you do have a 4" p-p second order harmonic. You mind what to try using adaptive PEC in PHD2, and set the period length to 239.34s, and let PHD2 guide out the 120s and 60s errors. If you use PEC then you will need at least two worm period in order to get the 240 and 120 errors. I would not both with the third order harmonic at 60s.
Now the your 76s error is 2.3" p-p. After correction is remains high at 1" p-p. It's twice the size of you 120 and 240s errors after correction This really limits the Ra performance of you mount greatly. We have ways to eliminate this error in the hackers forum.?
What does all this mean. Well your Ra rms error is twice you Dec error. For round stars you want them to be the same order of magnitude. If you got your Ra down to where the Dec axis is, your total rms error would drop from 0.7" to 0.5", which is very good, and seeing on any given night becomes the dominant factor and not your mount.
Peter?
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Re: RA axis movement or wiggle
Chip, if your Ra guide error is twice your Dec error will you get round stars?
Peter
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Re: RA axis movement or wiggle
Jim, if the wind is noticeably moving your spring loaded worm you might want to batten down the hatches?? you mitigate the wind effect somewhat with a blind of some sort. Most of the time wind gusts cause sudden jumps in dec and Ra that results in crap guiding. If you focal length is under 200 mm you might be OK.
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Re: Help with PemPro on G11/Gemini
That sounds?exactly like?what I¡¯m seeing! ?I¡¯ll have to try the ethernet connection ¡ thanks for pointer!
On Saturday, August 27, 2022, 4:50 PM, geordan@... wrote: The PEC options didn't appear for me when I was connected via USB, but did when I connected using Ethernet; see this thread?in the Gemini-II group.
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Re: Help with PemPro on G11/Gemini
The PEC options didn't appear for me when I was connected via USB, but did when I connected using Ethernet; see this thread?in the Gemini-II group.
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Re: Help with PemPro on G11/Gemini
Ok. I¡¯ll?ignore for now.?
On Saturday, August 27, 2022, 3:12 PM, Brian Valente <bvalente@...> wrote: PEMPro will overwrite what you already have, so that is probably moot as well
but it generally sounds like symptoms of not being connected.
Thanks, Brian.? Perhaps all of this is a moot point/issue then?? Assuming??PemPro is taking care of 2X PEC for me, a couple of oddities still remain (note I did use the?latest PemPro last night to upload a PEC) ¡
- I can¡¯t seem to permanently disable and/or clear the PEC ¡ despite everything I try on the physical and ASCOM hand controller, the PEC seems to get reenabled after a power cycle
- Not sure why I cannot get the PEC selection box to populate in the ascom driver
Is any of this cause for concern or should I just ignore and proceed with PemPro? On Saturday, August 27, 2022, 2:41 PM, Brian Valente <bvalente@...> wrote: Hi Bret
Wayback is correct the mount needs to be connected before these are populated, but this may be a moot point for you:
Use the latest PEMPro 3.0.0.46 and it will automatically set it to 2x cycle when connecting to your Gemini?
Hi WayBack,
Thanks for the suggestion. I retried and made sure I connected before going to the configure PEC window ¡ no luck ¡ the PEC selection box is?still blank.? I also tried uninstalling ASCOM and all drivers followed by downloading and reinstalling everything fresh ¡ no difference unfortunately.?
Hoping to try PemPro tonight if I can get past this step!
-Bret On Saturday, August 27, 2022, 1:27 PM, WayBack <corey_d@...> wrote: Probably not this but:?
If I open Gemini Telescope -> open subpage Configure PEC -> connect mount.? ?Then it behaves as you describe.
If I open Gemini Telescope -> connect mount -> open subpage Configure PEC (pauses here chatting with the mount).? ?Then it opens with selections.
-- Brian?
Brian Valente astro portfolio? portfolio astrobin?
-- Brian?
Brian Valente astro portfolio? portfolio astrobin?
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Re: Help with PemPro on G11/Gemini
PEMPro will overwrite what you already have, so that is probably moot as well
but it generally sounds like symptoms of not being connected.
Thanks, Brian.? Perhaps all of this is a moot point/issue then?? Assuming??PemPro is taking care of 2X PEC for me, a couple of oddities still remain (note I did use the?latest PemPro last night to upload a PEC) ¡
- I can¡¯t seem to permanently disable and/or clear the PEC ¡ despite everything I try on the physical and ASCOM hand controller, the PEC seems to get reenabled after a power cycle
- Not sure why I cannot get the PEC selection box to populate in the ascom driver
Is any of this cause for concern or should I just ignore and proceed with PemPro? On Saturday, August 27, 2022, 2:41 PM, Brian Valente <bvalente@...> wrote: Hi Bret
Wayback is correct the mount needs to be connected before these are populated, but this may be a moot point for you:
Use the latest PEMPro 3.0.0.46 and it will automatically set it to 2x cycle when connecting to your Gemini?
Hi WayBack,
Thanks for the suggestion. I retried and made sure I connected before going to the configure PEC window ¡ no luck ¡ the PEC selection box is?still blank.? I also tried uninstalling ASCOM and all drivers followed by downloading and reinstalling everything fresh ¡ no difference unfortunately.?
Hoping to try PemPro tonight if I can get past this step!
-Bret On Saturday, August 27, 2022, 1:27 PM, WayBack <corey_d@...> wrote: Probably not this but:?
If I open Gemini Telescope -> open subpage Configure PEC -> connect mount.? ?Then it behaves as you describe.
If I open Gemini Telescope -> connect mount -> open subpage Configure PEC (pauses here chatting with the mount).? ?Then it opens with selections.
-- Brian?
Brian Valente astro portfolio? portfolio astrobin?
-- Brian?
Brian Valente astro portfolio? portfolio astrobin?
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Re: Help with PemPro on G11/Gemini
Thanks, Brian. ?Perhaps all of this is a moot point/issue then? ?Assuming??PemPro is taking care of 2X PEC for me, a couple of oddities still remain (note I did use the?latest PemPro last night to upload a PEC) ¡
- I can¡¯t seem to permanently disable and/or clear the PEC ¡ despite everything I try on the physical and ASCOM hand controller, the PEC seems to get reenabled after a power cycle
- Not sure why I cannot get the PEC selection box to populate in the ascom driver
Is any of this cause for concern or should I just ignore and proceed with PemPro?
On Saturday, August 27, 2022, 2:41 PM, Brian Valente <bvalente@...> wrote: Hi Bret
Wayback is correct the mount needs to be connected before these are populated, but this may be a moot point for you:
Use the latest PEMPro 3.0.0.46 and it will automatically set it to 2x cycle when connecting to your Gemini?
Hi WayBack,
Thanks for the suggestion. I retried and made sure I connected before going to the configure PEC window ¡ no luck ¡ the PEC selection box is?still blank.? I also tried uninstalling ASCOM and all drivers followed by downloading and reinstalling everything fresh ¡ no difference unfortunately.?
Hoping to try PemPro tonight if I can get past this step!
-Bret On Saturday, August 27, 2022, 1:27 PM, WayBack <corey_d@...> wrote: Probably not this but:?
If I open Gemini Telescope -> open subpage Configure PEC -> connect mount.? ?Then it behaves as you describe.
If I open Gemini Telescope -> connect mount -> open subpage Configure PEC (pauses here chatting with the mount).? ?Then it opens with selections.
-- Brian?
Brian Valente astro portfolio? portfolio astrobin?
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Re: Help with PemPro on G11/Gemini
Hi Paul,
I was using v1.0.84. ?I just?installed v1.1.10 and tried again ¡ no difference.?
As for a previous PEC, yes as a matter fact ¡ I made a first attempt of using PemPro last night and uploaded a PEC curve. Afterwards I discovered Brian¡¯s instructions and I am trying repeat the PEC training following his instructions which led to the issue I¡¯m trying to get past.
I have since disabled PEC in the HC as well as the enabling on startup. ?I¡¯ve also tried multiple times to Clear PEC. ?But I¡¯m?noticing that every time power cycle Gemini, the PEC is being re-enabled ¡ perhaps this is connected to my problem?
-Bret
On Saturday, August 27, 2022, 1:55 PM, Paul Kanevsky <yh@...> wrote: Hi Bret, What version of Gemini.NET driver are you using? Might be worth a try to update to the latest test version (1.1.10) to see if that makes a difference: It looks like you already have PEC programmed. Can you try clearing it, and then see if the option for recording x2 PEC shows up? Regards, ? ? -Paul On Sat, Aug 27, 2022 at 12:58 PM, Bret Stott wrote:
Hi Folks,
I'm new to the G11/Gemini, but not to astrophotography and I have used PemPro previously with great success. ? I'm using Brian's fabulous instructions here:
but, I'm stuck in Gemini PEC setup in the very beginning. ?The problem I can't figure out is that Brian's instructions show that I'm supposed "Choose 2x PEC cycle and press Set", but the pulldown box is empty (see screenshot below). ??
What am doing wrong?
Thanks in advance!
-Bret
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Re: RA axis movement or wiggle
Thanks for all the responses.? ?The universal opinion is that 3mm wiggle is not an issue for general tracking.? ?But how about tolerance to wind?? ?I have been trying to use my 127mm refractor at f7.5 or f5.3 (with the reducer) and having difficulty even with a mild breeze.? ?Wind tonight is forecast to be 14mph and that is too much for this scope on my current mount.? ?Guiding without wind is generally good, but RMS guiding for RA is typically about twice the RMS for DEC? --? for the low/no wind case.? ?I suspect I could improve RA guiding? with a PEC, which I do not have at the moment.? ?I have found the PPEC with PHD2 does not work all that well in windy conditions, so I have abandoned that for windy nights.? ?So what can I do to make the mount/scope track/guide better in the wind?? ?Cable management could be improved, but right now I only have two cables (USB and power) going from the mount to the scope.? ? ?--? Jim
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Re: Help with PemPro on G11/Gemini
Hi Bret
Wayback is correct the mount needs to be connected before these are populated, but this may be a moot point for you:
Use the latest PEMPro 3.0.0.46 and it will automatically set it to 2x cycle when connecting to your Gemini?
Hi WayBack,
Thanks for the suggestion. I retried and made sure I connected before going to the configure PEC window ¡ no luck ¡ the PEC selection box is?still blank.? I also tried uninstalling ASCOM and all drivers followed by downloading and reinstalling everything fresh ¡ no difference unfortunately.?
Hoping to try PemPro tonight if I can get past this step!
-Bret On Saturday, August 27, 2022, 1:27 PM, WayBack <corey_d@...> wrote: Probably not this but:?
If I open Gemini Telescope -> open subpage Configure PEC -> connect mount.? ?Then it behaves as you describe.
If I open Gemini Telescope -> connect mount -> open subpage Configure PEC (pauses here chatting with the mount).? ?Then it opens with selections.
-- Brian?
Brian Valente astro portfolio? portfolio astrobin?
|
Re: Help with PemPro on G11/Gemini
Hi WayBack,
Thanks for the suggestion. I retried and made sure I connected before going to the configure PEC window ¡ no luck ¡ the PEC selection box is?still blank. ?I also tried uninstalling ASCOM and all drivers followed by downloading and reinstalling everything fresh ¡ no difference unfortunately.?
Hoping to try PemPro tonight if I can get past this step!
On Saturday, August 27, 2022, 1:27 PM, WayBack <corey_d@...> wrote: Probably not this but:?
If I open Gemini Telescope -> open subpage Configure PEC -> connect mount.? ?Then it behaves as you describe.
If I open Gemini Telescope -> connect mount -> open subpage Configure PEC (pauses here chatting with the mount).? ?Then it opens with selections.
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Re: Help with PemPro on G11/Gemini
Hi Bret,
What version of Gemini.NET driver are you using? Might be worth a try to update to the latest test version (1.1.10) to see if that makes a difference:
It looks like you already have PEC programmed. Can you try clearing it, and then see if the option for recording x2 PEC shows up?
Regards,
? ? -Paul
toggle quoted message
Show quoted text
On Sat, Aug 27, 2022 at 12:58 PM, Bret Stott wrote:
Hi Folks,
I'm new to the G11/Gemini, but not to astrophotography and I have used PemPro previously with great success. ? I'm using Brian's fabulous instructions here:
but, I'm stuck in Gemini PEC setup in the very beginning. ?The problem I can't figure out is that Brian's instructions show that I'm supposed "Choose 2x PEC cycle and press Set", but the pulldown box is empty (see screenshot below). ??
What am doing wrong?
Thanks in advance!
-Bret
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Re: Help with PemPro on G11/Gemini
Probably not this but:?
If I open Gemini Telescope -> open subpage Configure PEC -> connect mount.? ?Then it behaves as you describe.
If I open Gemini Telescope -> connect mount -> open subpage Configure PEC (pauses here chatting with the mount).? ?Then it opens with selections.
|
Re: Help with PemPro on G11/Gemini
On Sat, Aug 27, 2022 at 03:00 PM, Michael Herman wrote:
It's just too bad that no one will try a TeamViewer abusive the problem real time...instead of a dozen emails. ?
Sounds like you¡¯re volunteering, Michael ;)
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Re: Help with PemPro on G11/Gemini
I do not know, but it is certainly a solvable problem. May be the problem is with the ASCOM platform? The dialog is just what you shows, but no clue why the pulldown box is empty. I don't know if this setting can also be checked in the web interface.??
BTW I use ethernet to connect to Gemini.
Best of luck,
Daniel
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Re: Help with PemPro on G11/Gemini
It's just too bad that no one will try a TeamViewer abusive the problem real time...instead of a dozen emails.??
Hi Daniel,
Thanks for the quick response!? I believe I am doing exactly what you describe ... best as I can tell, I'm connected to mount and everything looks correct except that when I go to?setup->configure pec, there is no option to select?2x PEC cycle or anything else ... the pulldown box is empty.? I've waited 30 minutes, tried unconnecting/re-connecting, rebooting my PC and the mount, etc. ? ?I'm reattaching the screenshot from PC which may help someone identify what might be wrong.
Thanks for looking!
-Bret
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Re: RA axis movement or wiggle
On Fri, Aug 26, 2022 at 04:02 PM, Jim Magill wrote:
How much wiggle or movement should there be for the RA axis if the spring-loaded worm and secondary screw are adjusted correctly?? ?I measured the movement of the far end of the counterweight shaft and found 3mm of movement.? This seems excessive.? ?I had less movement but was forced to back off the secondary screw because the RA motor was stalling.? ?Is there something else other than the secondary screw that might be causing/contributing to this 3mm of movement?? ?Is there anything different about adjusting the secondary screw for the RA axis compared to the secondary screw for the DEC axis?? ?The DEC axis had some movement and I was able to significantly reduce it by adjusting the spring-loaded worm and secondary screw for DEC.? ?My mount is a GM811G and is about a year old.? ?I use it a lot, about 130 nights of imaging/testing since purchase.? ?Thanks in advance for any advice.? ? --? Jim?
Hi Jim,? This tiny movement is not an issue. If you consider how much backlash is in play 30" upstream. Also consider that given that RA is driven in only one direction the now even smaller backlash really makes no difference in PE. Plus the drive is moving only in one direction so backlash is typically irrelevant except in a perfectly balanced mount or in widy conditions.? The nature of spring loaded worms is if you introduce artificial forces into the system you are forcing the spring mechanism to work in ways the system does not encounter when in actual use. Just leave it alone if you have round stars. All you will do by creating a problem is reduce your mount real world performance.?? -- Chip Louie Chief Daydreamer Imagination Hardware?
? ?Astropheric Weather Forecast - South Pasadena, CA?
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Paul Kanevsky
Michael Herman
Chip Louie