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Encoders, yes or no?

 

All,
Sorry for the barrage of newby questions, I am working my way through the manual to get to grips with all the features on the G11, my first motorised eq, tonight's topic of interest is Encoders.
If I understand there are 2 types of Encoders, the type that is incorporated into the motor, this type uses pins on the motor din plugs to connect, and the other type that fits to the RA and DEC shafts and connects to Gemini via the encoder RJ45 socket..Please correct my if I am wrong!

I understand what they do so my questions are:
Except for manual guiding when attached to a computer running Stellarium were the benefit is obvious,? are they useful for any other purpose and worth the money?

What is the best type, motor or shaft?

Thank you in advance..
 

I’ve had my GM8 since the 90s. At the time there was no Gemini goto unit for the Losmandy mount except for a third party after market mod. The encoders that attached to the RA/Dec gave push to capability to the mount when connected to a computer or a unit such as the JMImini max. With the introduction of the Gemini, the mount needed better resolution and that came with the new upgraded motors instead of the old stepper motors.?

Bill

On Sat, Oct 3, 2020 at 17:02, Dave_Kentsbeer <david.kentsbeer47@...> wrote:
All,
Sorry for the barrage of newby questions, I am working my way through the manual to get to grips with all the features on the G11, my first motorised eq, tonight's topic of interest is Encoders.
If I understand there are 2 types of Encoders, the type that is incorporated into the motor, this type uses pins on the motor din plugs to connect, and the other type that fits to the RA and DEC shafts and connects to Gemini via the encoder RJ45 socket..Please correct my if I am wrong!

I understand what they do so my questions are:
Except for manual guiding when attached to a computer running Stellarium were the benefit is obvious,? are they useful for any other purpose and worth the money?

What is the best type, motor or shaft?

Thank you in advance..









--
_____________

Pictor Observatory

Twitter: @pictorobs

Minor Planet 21350 - billgardner
 

Hi Dave

This is a fairly easy one - encoders are included as part of the mount

There is a port F that was designed for the idea of future external encoders but that did not come to pass.

So the baseline mount already comes with all the encoder options available



Brian




On Sat, Oct 3, 2020 at 2:02 PM Dave_Kentsbeer <david.kentsbeer47@...> wrote:
All,
Sorry for the barrage of newby questions, I am working my way through the manual to get to grips with all the features on the G11, my first motorised eq, tonight's topic of interest is Encoders.
If I understand there are 2 types of Encoders, the type that is incorporated into the motor, this type uses pins on the motor din plugs to connect, and the other type that fits to the RA and DEC shafts and connects to Gemini via the encoder RJ45 socket..Please correct my if I am wrong!

I understand what they do so my questions are:
Except for manual guiding when attached to a computer running Stellarium were the benefit is obvious,? are they useful for any other purpose and worth the money?

What is the best type, motor or shaft?

Thank you in advance..



--
Brian?



Brian Valente
portfolio

 

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If you are using a Gemini controller, you have the motor encoders.

?

So the question is what’s the point of axis encoders – it buys you the ability to use the mount in “push to” mode while keeping the Gemini-1 informed of where the mount is pointing.

?

Also if there’s any slip in the system the axis encoders act to correct for that.

?

Sadly the Gemini-2 doesn’t have code to support axis encoders which is a real shame.

?

René – is that any reason the axis encoder support couldn’t be ported across to the Gemini-2 – my guess is it should be trivial to do this – possibly even with support for higher resolution eoncoders?

?

David

From: [email protected] [mailto:[email protected]] On Behalf Of Dave_Kentsbeer
Sent: 03 October 2020 22:02
To: [email protected]
Subject: [Losmandy_users_io] Encoders, yes or no?

?

All,
Sorry for the barrage of newby questions, I am working my way through the manual to get to grips with all the features on the G11, my first motorised eq, tonight's topic of interest is Encoders.
If I understand there are 2 types of Encoders, the type that is incorporated into the motor, this type uses pins on the motor din plugs to connect, and the other type that fits to the RA and DEC shafts and connects to Gemini via the encoder RJ45 socket..Please correct my if I am wrong!

I understand what they do so my questions are:
Except for manual guiding when attached to a computer running Stellarium were the benefit is obvious,? are they useful for any other purpose and worth the money?

What is the best type, motor or shaft?

Thank you in advance..

 

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No, axis encoders aren’t included, only motor encoders.

?

David

?

From: [email protected] [mailto:[email protected]] On Behalf Of Brian Valente
Sent: 04 October 2020 00:54
To: [email protected]
Subject: Re: [Losmandy_users_io] Encoders, yes or no?

?

Hi Dave

?

This is a fairly easy one - encoders are included as part of the mount

?

There is a port F that was designed for the idea of future external encoders but that did not come to pass.

?

So the baseline mount already comes with all the encoder options available

?

?

?

Brian

?
 

David I think if you read what I said it’s true. It’s all the encoders we have available for the Gemini which are the motor encoders.?

Brian


On Sat, Oct 3, 2020 at 6:30 PM David C. Partridge <david.partridge@...> wrote:

No, axis encoders aren’t included, only motor encoders.

?

David

?

From: [email protected] [mailto:[email protected]] On Behalf Of Brian Valente
Sent: 04 October 2020 00:54
To: [email protected]
Subject: Re: [Losmandy_users_io] Encoders, yes or no?

?

Hi Dave

?

This is a fairly easy one - encoders are included as part of the mount

?

There is a port F that was designed for the idea of future external encoders but that did not come to pass.

?

So the baseline mount already comes with all the encoder options available

?

?

?

Brian

?











--
Brian?



Brian Valente
portfolio

 

On Sat, Oct 3, 2020 at 09:28 PM, David C. Partridge wrote:

?

Sadly the Gemini-2 doesn’t have code to support axis encoders which is a real shame.

?

René – is that any reason the axis encoder support couldn’t be ported across to the Gemini-2 – my guess is it should be trivial to do this – possibly even with support for higher resolution eoncoders?

Support for high resolution axis encoders would be a great new feature! :) When done well, these could eliminate the need for PEC and, sometimes guiding.

Regards,

? ? -Paul
 

I have a GM8 with a Gemini 1 which I had kept for the ability to use with shaft encoders. The problem is the Gemini 1 only supports 10K tic encoders and modern encoders as sold by Astro Devices for the Losmandy mounts are 310K tic encoders so they do not work with Gemini but work great with the WiFi enabled NEXUS DSC with a smartphone or tablet. I love to use the GM8 in PUSH-TO mode with the mount balanced and the clutches free for one finger movement. It works very well as the Gemini still moves the RA just fine once I find an object. This is the best way to use a Losmandy mount IMO?
?
--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?
 

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You aren’t the only source of shaft encoders for Losmandy mounts …

?

David

?

From: [email protected] [mailto:[email protected]] On Behalf Of Brian Valente
Sent: 04 October 2020 02:33
To: [email protected]
Subject: Re: [Losmandy_users_io] Encoders, yes or no?

?

David I think if you read what I said it’s true. It’s all the encoders we have available for the Gemini which are the motor encoders.?

?

Brian
 

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Astro Devices will do “special order” low res encoders that will work with the G1 …

?

David

?

From: [email protected] [mailto:[email protected]] On Behalf Of Chip Louie
Sent: 04 October 2020 04:59
To: [email protected]
Subject: Re: [Losmandy_users_io] Encoders, yes or no?

?

I have a GM8 with a Gemini 1 which I had kept for the ability to use with shaft encoders. The problem is the Gemini 1 only supports 10K tic encoders and modern encoders as sold by Astro Devices for the Losmandy mounts are 310K tic encoders so they do not work with Gemini but work great with the WiFi enabled NEXUS DSC with a smartphone or tablet. I love to use the GM8 in PUSH-TO mode with the mount balanced and the clutches free for one finger movement. It works very well as the Gemini still moves the RA just fine once I find an object. This is the best way to use a Losmandy mount IMO?
?
--

Chip Louie Chief Daydreamer Imagination Hardware?
 

Hi all, thank you for the great responses, there is a lot to learn with Astro gear and I have a long way to go, I don't intend to use push to so dont think I need the shaft encoders, if I'm honest I didn't realise the motors had encoders, I assumed they were an upgrade but googling last night realised that the goto system needs them to work.

Thanks again.?
Sonny Edmonds
 

I like Scott's personal advice to me at the time of my Purchase:
"Don't tinker with it, just use it."
As it is, my Losmandy mount works perfectly.

https://www.cloudynights.com/uploads/gallery/album_8062/gallery_252608_8062_305774.jpeg

--
SonnyE


(I suggest viewed in full screen)
 

Hi David,

Serge told me the magnetic rings are the same. The difference is on the pickup side of the encoders which are programed to count differently which yields you a 10K tic encoder system. I have not tried them as I wanted the highest working resolution so I stuck with standard 310K tics for the Nexus DSC which is amazing in use.?

--

Chip Louie Chief Daydreamer Imagination Hardware?

? ?Astropheric Weather Forecast - South Pasadena, CA?
 

I use my? upgraded 2010 Losmandy G11G for imaging. The wish list would be to improve guiding using absolute encoders.? If my understanding is correct, the E port on the Gemini-2 is not designed to support that.?
?
With that said, I would pay the dollars to add absolute encoders and placing this on the Gemini-2 road map would be fantastic.
?
 

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As would some other folks, but you have to convince Scott Losmandy to do that.? Ideally this would require a new generation of Gemini (Gemini-3?) with the necessary additional hardware and firmware to talk to the absolute encoders.?? I think it would also be possible to create a smallish additional box that would allow them to be used with the Gemini-2.??? He’d also need to supply the hardware to me as it is likely that I’d end up developing the firmware to support the encoders.

?

Adding absolute encoders to an existing mount would be a major exercise involving disassembly of the mount and quite a bit of precision machining.

?

So, if it were ever offered, I suspect it would have to be with a new version of the mount, as for most people the cost of shipping the mount back to Losmandy, paying for the work and dealing with the complication of international customs such that you only pay tax/duty on the upgrade charges when it is shipped back to you.?? In the current “trade war” those charges could be huge.

?

Please don’t discuss the politics here.

?

David

From: [email protected] <[email protected]> On Behalf Of jim.bachesta via groups.io
Sent: 12 March 2025 17:54
To: [email protected]
Subject: Re: [Losmandy_users_io] Encoders, yes or no?

?

I use my? upgraded 2010 Losmandy G11G for imaging. The wish list would be to improve guiding using absolute encoders.? If my understanding is correct, the E port on the Gemini-2 is not designed to support that.?

?

With that said, I would pay the dollars to add absolute encoders and placing this on the Gemini-2 road map would be fantastic.

?
 

Some time ago Gemini and the digital servo made the few remaining advantages for absolutely encoders impractical.?
 

On Thu, Mar 13, 2025 at 06:06 AM, WayBack wrote:
Some time ago Gemini and the digital servo made the few remaining advantages for absolutely encoders impractical.?
?
Not really.? The servos just use encoders for the motor position which may or may not be well related to the actual shaft positions.? For real-time position data you need to look at shaft/axle position which the servo motors cannot actually know.?
?
Absolute encoders on the shafts are absolutely possible, I have the 311,000 tic encoders on two mounts right now for use with Nexus DSC and Sky Safari.? To get serious sub arc second resolution gets very expensive depending on how much resolution and how it will be used.??
?
--

Chip Louie Chief Daydreamer Imagination Hardware?

Astrospheric Forecast - South Pasadena, CA?
?
?
?
 

On Thu, Mar 13, 2025 at 02:20 PM, Chip Louie wrote:
and how it will be used.?
Exactly, practical use of the mount won't improve with more encoders than those already present, unless some use case warrants this.? And most use cases were covered with Gemini.? Given its age and enhancements, it's why it so remarkable.
 

On Thu, Mar 13, 2025 at 03:48 AM, David C. Partridge wrote:

As would some other folks, but you have to convince Scott Losmandy to do that.? Ideally this would require a new generation of Gemini (Gemini-3?) with the necessary additional hardware and firmware to talk to the absolute encoders.?? I think it would also be possible to create a smallish additional box that would allow them to be used with the Gemini-2.??? He’d also need to supply the hardware to me as it is likely that I’d end up developing the firmware to support the encoders.

?

Adding absolute encoders to an existing mount would be a major exercise involving disassembly of the mount and quite a bit of precision machining.

?

So, if it were ever offered, I suspect it would have to be with a new version of the mount, as for most people the cost of shipping the mount back to Losmandy, paying for the work and dealing with the complication of international customs such that you only pay tax/duty on the upgrade charges when it is shipped back to you.?? In the current “trade war” those charges could be huge.

?

Please don’t discuss the politics here.

?

David?

?
The problem is not actually building a Losmandy mount with absolute encoders, I have no doubt that Losmandy could design and produce such a mount.? The problem is getting enough people to buy the resulting mount as the cost would be quite high.? Even if you simply added an RA axis encoder ring and the double read heads needed to get the required resolution your talking about doubling the cost of a G11G just for the all new mount hardware design BEFORE you get to the all new controller hardware and new version firmware you will need to run the G11G+Absolute Encoder mount.?
?
So would you pay nearly $8,000 for a 65 pound payload mount with absolute encoder RA?? Would you pay $10,000 for a dual axis absolute encoder mount that did not need guiding for the commonly used short subframe imaging we use today?? I don't think so because in reasonably skilled hands, modern autoguiding on current model G11G mounts is already good enough to produce excellent images for most sub 2,000mm focal length optics.? Not to mention that with all the money you saved you could buy an entire second imaging rig.? ? ??
?
--

Chip Louie Chief Daydreamer Imagination Hardware?

Astrospheric Forecast - South Pasadena, CA?
?
?
?
 

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I tend to agree with you agree with you Chip - the cost of the encoders is pretty darn steep and the number of takers would likely be low.

?

If folks do insist on having high res axis encoders then I guess they are probably going to look at 10-Micron or AP at costs north of about 10k or more.

?

Given that a G11 and Gemini combo can deliver approx. 1 arc-seconds RMS tracking error …

?

PS Ganymede subtends about 1.5 arc-seconds as seen from here.

?

?

D.

?

?

?

?

?

From: [email protected] <[email protected]> On Behalf Of Chip Louie via groups.io
Sent: 13 March 2025 20:56
To: [email protected]
Subject: Re: [Losmandy_users_io] Encoders, yes or no?

?

On Thu, Mar 13, 2025 at 03:48 AM, David C. Partridge wrote:

As would some other folks, but you have to convince Scott Losmandy to do that.? Ideally this would require a new generation of Gemini (Gemini-3?) with the necessary additional hardware and firmware to talk to the absolute encoders.?? I think it would also be possible to create a smallish additional box that would allow them to be used with the Gemini-2.??? He’d also need to supply the hardware to me as it is likely that I’d end up developing the firmware to support the encoders.

?

Adding absolute encoders to an existing mount would be a major exercise involving disassembly of the mount and quite a bit of precision machining.

?

So, if it were ever offered, I suspect it would have to be with a new version of the mount, as for most people the cost of shipping the mount back to Losmandy, paying for the work and dealing with the complication of international customs such that you only pay tax/duty on the upgrade charges when it is shipped back to you.?? In the current “trade war” those charges could be huge.

?

Please don’t discuss the politics here.

?

David?

?

The problem is not actually building a Losmandy mount with absolute encoders, I have no doubt that Losmandy could design and produce such a mount.? The problem is getting enough people to buy the resulting mount as the cost would be quite high.? Even if you simply added an RA axis encoder ring and the double read heads needed to get the required resolution your talking about doubling the cost of a G11G just for the all new mount hardware design BEFORE you get to the all new controller hardware and new version firmware you will need to run the G11G+Absolute Encoder mount.?

?

So would you pay nearly $8,000 for a 65 pound payload mount with absolute encoder RA?? Would you pay $10,000 for a dual axis absolute encoder mount that did not need guiding for the commonly used short subframe imaging we use today?? I don't think so because in reasonably skilled hands, modern autoguiding on current model G11G mounts is already good enough to produce excellent images for most sub 2,000mm focal length optics.? Not to mention that with all the money you saved you could buy an entire second imaging rig.? ? ??

?

--


Chip Louie Chief Daydreamer Imagination Hardware?

Astrospheric Forecast - South Pasadena, CA?

?

?

?

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