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?
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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
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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.
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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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Re: Help with PemPro on G11/Gemini
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
Interesting, operationally the 3mm movement does not exist.? Push on the DEC shaft let go and it will return to the starting point because the force creates movement by pushing against the worm spring mechanism.? Because in use no similar force will exist to push the DEC shaft (small children excluded), no 3mm play exists in operation.? Which excludes thinking of the movement as backlash, but wiggle might apply (spring compression).
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Re: RA axis movement or wiggle
>>>
I really thought that the direction of the arrows you see in PHD2 indicated the turning direction of the RA drive.?
it's the direction of the guidepulse, but RA axis never stops or reverses
On Sat, Aug 27, 2022 at 03:06 AM, Brian Valente wrote:
it guides in one direction all?the time. RA is moving in sidereal speed, so guide corrections are either speeding up or slowing down the RA movement. it's never reversing so backlash during tracking and guiding is not a performance issue
Thanks for the clarification. I really thought that the direction of the arrows you see in PHD2 indicated the turning direction of the RA drive.?
Best wishes,
Daniel
-- Brian?
Brian Valente astro portfolio? portfolio astrobin?
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Re: Resetting spring-loaded worm
I'm attaching last night log.? I'm not sure if this is the best I can post, because I used dithering and this makes analysis more difficult.? I'm aware of the machanical causes of all the main spikes in the error spectrum, but what I'm not sure is if the RA Axis could benefit from some loosening of the bottom cap screw, that is, if such loosening could smooth a little the error plot.
Best,
Daniel
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Re: Help with PemPro on G11/Gemini
Load the Gemini 2 driver,? click to show the hand controller window, connect to the gemini 2 and then, setup->configure pec? which, after some time, will brought to you the PEC configuration dialog in which you can set the 2x PEC cycle.
Regards,
Daniel
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Help with PemPro on G11/Gemini
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
On Sat, Aug 27, 2022 at 03:06 AM, Brian Valente wrote:
it guides in one direction all?the time. RA is moving in sidereal speed, so guide corrections are either speeding up or slowing down the RA movement. it's never reversing so backlash during tracking and guiding is not a performance issue
Thanks for the clarification. I really thought that the direction of the arrows you see in PHD2 indicated the turning direction of the RA drive.? Best wishes, Daniel
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Re: RA axis movement or wiggle
That¡¯s about right. There has to be som movement I remember this has been discussed lots before. ?3mm at the end of the shaft is a lot less at the gear?
--
Brendan
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Re: RA axis movement or wiggle
Backlash in Ra is not a thing! My focus would be on Dec. You need an FFT on Ra to understand it's behaviour.
Peter
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Re: RA axis movement or wiggle
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"
>>>
?Backlash in RA is not a big thing as it tends to guide in one direction most of the time.??
it guides in one direction all?the time. RA is moving in sidereal speed, so guide corrections are either speeding up or slowing down the RA movement. it's never reversing so backlash during tracking and guiding is not a performance issue
Even with this backlash, how is your guiding ?? ?Backlash in RA is not a big thing as it tends to guide in one direction most of the time.??
Regards,
Daniel
-- Brian?
Brian Valente astro portfolio? portfolio astrobin?
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Re: RA axis movement or wiggle
Because it's spring-loaded, you'll see a lot of wiggle if you push moderately hard, but that doesn't mean you have that much backlash during normal tracking.
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Paul Kanevsky
Michael Herman
Chip Louie