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Re: WHY??

 

At some point if I decide to up my game, I may try an AO device. That seems to be somewhat of a silver bullet, and maybe cheaper than getting a higher end mount. For now I'm have to say that I'm really happy with my GM811G. I've had it for a couple of years, and it's taken me a while to learn how to adjust it, but I tend to get very reliable results over long periods without doing any adjustments. I just take it outside, setup and start imaging. It seems that the worm might need adjusting once in spring and once in fall. I tend to get results that range from 1.1 to 0.4 RMS, and that suits me just fine. When multi-star came out I saw results below 0.4 RMS for the first time. I was worried that it was just a fluke. I'm guessing that it only happens when seeing is good, but I've seen it fairly regularly over the last few months. The last few nights of imaging I was getting guiding around 0.5 RMS with it dipping into the low 0.4's. I only get obsessed with tweaking things for performance when I'm imaging small things like the cat's eye which I was doing last night. -- and I didn't have to tweak a single thing, it just worked!?



An AO device may be what I do for a future upgrade if I want to get better images with the small objects. I'm also wondering how sensitive cameras will get over time. Maybe subs will get shorter and shorter making all this work tweaking the mechanics obsolete?

Jamie





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Re: ASCOM Device Hub or not

 

Hi Edward,

That's correct. Gemini.NET implements a local server ASCOM pattern and runs in its own process space. It can be shared by multiple client apps through COM, regardless of whether they are 64- or 32-bit processes.?

Indeed, POTH is an extremely useful piece of software, just not for the reasons that were mentioned in this thread :)

Regards,

? ? ?-Paul


On Mon, Jun 14, 2021 at 12:37 PM, Edward Plumer wrote:
Paul, Thanks. Since I am not much concerned about TheSkyX, I will stick to my original question about Gemini driver.? To clarify, are you saying that Gemini always runs out of process as a DCOM service regardless of what client invokes it??

By the way, though this does not invalidate anything you said, I might point out that another key functionality of POTH/ADH is that it provides middleman functionality. Of interest to me has been slaving dome rotation to the mount ( yes, my use of POTH has been a tangle of reasons). In using NINA, I am now able to let it do the dome slaving. This thread has clarified that, with Gemini, I no longer need POTH for connection sharing either ... awesome.
--
Edward
Re: next podcast topic: dovetail plates

 

How about easy solutions for co-aligning side-by-side setups. I went through a bunch of kludges for the Venus Transit and eclipse to get two OTA to both center the sun.
--
Edward
next podcast topic: dovetail plates

Brian Valente
 

¿ªÔÆÌåÓý

Hi folks

?

The main topic for our next podcast will be Losmandy dovetails.

?

I wanted to see what Dovetail-related questions anyone might have that we can try to answer

?

?

It will be more in depth and discuss things like history, hole patterns, radius blocks, D vs. V style, etc.

?

?

We will also be introducing a new ¡°configurable dovetail¡± option in our catalog, so you can customize your dovetail when you order it

?

?

?

Thanks

?

Brian

?

Brian Valente

Losmandy Astronomical

?

Losmandy.com

Tutorials and vids at

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Re: ASCOM Device Hub or not

 

Edward - I just want to clarify (and I think you know this) that the Gemini ASCOM driver is a hub itself.

there are some ascom drivers that aren't a hub and require a third party hub middleware kind of approach. Optec has an interesting one as well




On Mon, Jun 14, 2021 at 9:37 AM Edward Plumer <eplumer@...> wrote:
Paul, Thanks. Since I am not much concerned about TheSkyX, I will stick to my original question about Gemini driver.? To clarify, are you saying that Gemini always runs out of process as a DCOM service regardless of what client invokes it??

By the way, though this does not invalidate anything you said, I might point out that another key functionality of POTH/ADH is that it provides middleman functionality. Of interest to me has been slaving dome rotation to the mount ( yes, my use of POTH has been a tangle of reasons). In using NINA, I am now able to let it do the dome slaving. This thread has clarified that, with Gemini, I no longer need POTH for connection sharing either ... awesome.
--
Edward



--
Brian?



Brian Valente
portfolio

Re: ASCOM Device Hub or not

 

Paul, Thanks. Since I am not much concerned about TheSkyX, I will stick to my original question about Gemini driver.? To clarify, are you saying that Gemini always runs out of process as a DCOM service regardless of what client invokes it??

By the way, though this does not invalidate anything you said, I might point out that another key functionality of POTH/ADH is that it provides middleman functionality. Of interest to me has been slaving dome rotation to the mount ( yes, my use of POTH has been a tangle of reasons). In using NINA, I am now able to let it do the dome slaving. This thread has clarified that, with Gemini, I no longer need POTH for connection sharing either ... awesome.
--
Edward
Re: WHY??

 

I assume that most who are trying to fine-tune guiding are not using AO. As you say, there's little need to improve guiding if AO is making the corrections. Re-centering the star when it's getting out of frame doesn't have to be very precise, just close enough. The AO will take care of making precise corrections after the guider bump.

Regards,

? ? ?-Paul


On Mon, Jun 14, 2021 at 02:40 AM, Les Niles wrote:
If you¡¯re imaging at 120 Hz, or even at 10 Hz, isn¡¯t the guiding immaterial? ?Guiding doesn¡¯t happen anywhere near that fast; any drift should be handled by the registration before stacking. ?For that matter, at 120 Hz it¡¯s hardly necessary to even track, except to keep the target from drifting out of the frame. ?
? -Les
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Re: Changing the servo motor encoders from 256 to 512 or 1024. Any reason not to do this?

 

One thing to realize is that Gemini has a greater internal precision than just one step. It reads stock servo encoders in quadrature, meaning it's capable of detecting an offset of 1/4 of a step size. For G11, one step is 0.5625 arcsec, so the actual offset can be detected with precision of up to 0.1406 arcsecs.?

Regards,

? ? ?-Paul


On Sun, Jun 13, 2021 at 10:30 PM, Cyclone wrote:
The Gemini L4 manual states:
"In addition to support for Losmandy and Mountain Instruments mounts, Gemini L4 now?supports custom mounts. The user can setup the main parameters of his mount: the gear?ratios and direction of spur gear and worm gear and the servo motor encoder resolution.?The step resolution can reach from 0.1 arcsec per step (servo motor encoder tick) up to?2.5 arcsec/step."

The serial commands definition L5 v2.1 states:
"Gemini L4 supports step sizes from 0.2 arcsec/tick to 2.5 arcsec/tick."

Therefore it is unclear what the minimum step size is, but both definitions would support a 512 tick encoder assuming you do not modify the gearbox.

Also, I wrote a document a while ago that explains how to calculate the step sizes which you may find useful (see attached).

Eric
Re: Changing the servo motor encoders from 256 to 512 or 1024. Any reason not to do this?

 

Hmmmm Many thanks.....it odd considering the inner optical pick-up is AVAGO Broadcom but the rest looks US digital.

I still find it Not quite right.?? Each assy is the same......actually ..... looks to be the same...apart from code wheels


--
Brendan
Re: WHY??

 

¿ªÔÆÌåÓý

If you¡¯re imaging at 120 Hz, or even at 10 Hz, isn¡¯t the guiding immaterial? ?Guiding doesn¡¯t happen anywhere near that fast; any drift should be handled by the registration before stacking. ?For that matter, at 120 Hz it¡¯s hardly necessary to even track, except to keep the target from drifting out of the frame. ?

? -Les



On 13 Jun 2021, at 13:50, Henk Aling <haling@...> wrote:

As a rule of thumb, without adaptive optics you will not get better resolution for apertures larger than 8".? So for visual, a 6" frac will be as good as a 12" SCT for almost every day of the year.? Of course resolution is not everything, light flux matters too.? For planetary observing imaging at 120+ Hz we depend on lucky seeing so the stacker picks the frames for which the Dawes limit matters.? So yes, it matters.

PS I made a mistake, 130/30 is not 0.25 but more like 0.4 but the conclusion remains that 0.7 is not good enough.

Re: WHY??

 

The answer might be location, location, location....

With east coast light pollution and the generally poor seeing from suburbia, the best I am getting is about 0.5" guiding around the zenith. Down at 30 degrees altitude about 1.0 guiding is average on a good night.? My 9.25 inch SCT is probably the most aperture local conditions will support. An 11" might be useable some of the time, but a 14" would probably be a fruitless effort for deep sky imaging. So even if I had super accurate mount, the air currents would probably bloat and distort the longer focal lengths and the cost of equipment wouldn't be worth it.?

Now if I had some Bortle 3 or less skies at some desert location with stable air, then the extra precision and investment in bigger and better equipment might be justified. And nearest dark sky site is about 4 hours away, so not a road trip that can be done on a regular basis with the larger equipment.
Re: Changing the servo motor encoders from 256 to 512 or 1024. Any reason not to do this?

 

Brenden, I asked US Digital about that and they said each encoder wheel has a matching reader. They are not interchangeable it seems. I was supplied too!
Re: Changing the servo motor encoders from 256 to 512 or 1024. Any reason not to do this?

 

I agree with your analysis. The gearbox from the pinion gear through to final drive gear generates most of the high frequency noise with the exception of seeing that PHD2 tries to eliminate. When I miss drilled the pinion gear for the 1/8th motor shaft I had a visably noticeable wobble, that generated at least a 0.5 arc sec guide error ?with a period of 9.2s. It was a very distinct sine wave on the guide chart. You can imagine my guiding was pretty bad, but no worse than 1.3 rms arc sec or so. I gained a whole new appreciation for these higher frequency noise components through just that error on my part. Really, I'd like to get ride of the gear box. These high frequencies can not be corrected for.?With a step size resolution of 0.56 arc sec guiding is actually worsened I feel.
Re: Changing the servo motor encoders from 256 to 512 or 1024. Any reason not to do this?

 

Michael,
I have a G11 with Gemini 2 and a McLennan gearbox on the RA axis. I have programmed PEC using 3 methods: built in PEC training, PEMPRO and my own PEC programming software, and did not run into the issue you described. Do you have a link to another post where you discuss the issues with programming PEC on your G11T?

Eric
Re: Changing the servo motor encoders from 256 to 512 or 1024. Any reason not to do this?

 

Hi Eric,

That was a very detailed and informative document.? Thank you for writing it up.

On my G-2 equipped G11T mount, I had fitted a McLennan 25:1 gearbox on the RA.? I then set the mount to Custom and changed the RA from -270 to +270 to change the motor Sidereal tracking direction.??

I tried the built in PEC on this G11T mount.? It did not work.? Each time I initiated a PEC run, the PEC program in Gemini-2 terminated prematurely.? It had to run for at least one 319.12 sec worm cycle, and it did not.? ?I reported the problem to Rene Goerlich in an email, but we never resolved the problem.? ?

Therefore the only way to use PEC on this G11T system is to use PEMpro.? I don't know if anyone else successfully got PEC to work on a G11.? If that PEC training also terminates prematurely of course no valid PEC curve will come out of the effort.?

That was an unwelcome surprise because my Gemini-1 units worked fine generating PEC that worked, on my G11 mounts.? I have not yet tried to run a PEC run on my G11T using my Gemini-1 units.? If that did work I think I could upload the correction file to the Gemini-2 using the Gemini.net applet.

All the best, and thanks again,
Michael?



On Sun, Jun 13, 2021, 7:30 PM Cyclone <148cyclone1@...> wrote:
The Gemini L4 manual states:
"In addition to support for Losmandy and Mountain Instruments mounts, Gemini L4 now?supports custom mounts. The user can setup the main parameters of his mount: the gear?ratios and direction of spur gear and worm gear and the servo motor encoder resolution.?The step resolution can reach from 0.1 arcsec per step (servo motor encoder tick) up to?2.5 arcsec/step."

The serial commands definition L5 v2.1 states:
"Gemini L4 supports step sizes from 0.2 arcsec/tick to 2.5 arcsec/tick."

Therefore it is unclear what the minimum step size is, but both definitions would support a 512 tick encoder assuming you do not modify the gearbox.

Also, I wrote a document a while ago that explains how to calculate the step sizes which you may find useful (see attached).

Eric
Re: Changing the servo motor encoders from 256 to 512 or 1024. Any reason not to do this?

 

The Gemini L4 manual states:
"In addition to support for Losmandy and Mountain Instruments mounts, Gemini L4 now?supports custom mounts. The user can setup the main parameters of his mount: the gear?ratios and direction of spur gear and worm gear and the servo motor encoder resolution.?The step resolution can reach from 0.1 arcsec per step (servo motor encoder tick) up to?2.5 arcsec/step."

The serial commands definition L5 v2.1 states:
"Gemini L4 supports step sizes from 0.2 arcsec/tick to 2.5 arcsec/tick."

Therefore it is unclear what the minimum step size is, but both definitions would support a 512 tick encoder assuming you do not modify the gearbox.

Also, I wrote a document a while ago that explains how to calculate the step sizes which you may find useful (see attached).

Eric
Re: ASCOM Device Hub or not

 

Folks, please let¡¯s not guess as this information is incorrect. Gemini.NET driver is itself a hub and requires no additional hubs unless something is misconfigured. Any number of applications can connect to Gemini.net at the same time. There¡¯s no limit or restriction on the number or bit-size of these apps.

Regards,

? ?-Paul


On Sun, Jun 13, 2021 at 07:49 PM, Pete wrote:

The hub is ASCOM 6.5SP1 Is focuser a useful tool is you connect your mount or focuser to more than one ASCOM client during a session.? Using the hub allows simultaneous to say, Stellarium PHD2, and SharpCap.? If you only wok with one client e.g. Stellarium then you do not need the ASCOM hub.

It is necessary to setup the ASCOM drivers (Gemini.net, etc.) being used by the hub from within the hub since Stellarium would only look at the hub if selected.?

I have used Stellarium as an example but the above applies to most of the ASCOM compatible planetarium Windows programs.

I hope this helps.
Pete
Re: ASCOM Device Hub or not

 
Edited

The hub is ASCOM 6.5SP1 Is focuser a useful tool is you connect your mount or focuser to more than one ASCOM client during a session.? Using the hub allows simultaneous to say, Stellarium PHD2, and SharpCap.? If you only wok with one client e.g. Stellarium then you do not need the ASCOM hub.

It is necessary to setup the ASCOM drivers (Gemini.net, etc.) being used by the hub from within the hub since Stellarium would only look at the hub if selected.?

I have used Stellarium as an example but the above applies to most of the ASCOM compatible planetarium Windows programs.

I hope this helps.
Pete
Re: Losmandy G11 motor datasheet

 

Enol,

The motors are DC.? The connectors are German DIN standard.

The 6 pins are arranged in a semicircle.? The outer metal shell is not used.??

The 2 end pins go to the DC motor wires.

The middle 4 pins go to a HEDS type optical encoder system.? You can read how they work.? They have 5 pins but only 4 of those are used by the Gemini system.??

The Gemini-1 manual explains much about the system. See attached.

Michael






On Sun, Jun 13, 2021, 3:26 PM Boreack <enolmbgi26@...> wrote:
Hi,

I have a Gemini 1 in my G11, the version with the big circular conectors pointing to the botom of the mount, and not to the side.
Not a tucked version.
What are the polarity of the cables, the steps and reduction of this type of motors?
I'm searching for info, but could not find it.

Greetings, Enol.

Losmandy G11 motor datasheet

Boreack
 

Hi,

I have a Gemini 1 in my G11, the version with the big circular conectors pointing to the botom of the mount, and not to the side.
Not a tucked version.
What are the polarity of the cables, the steps and reduction of this type of motors?
I'm searching for info, but could not find it.

Greetings, Enol.
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