NGC5371 and surrounding galaxies


Roland Christen
 

Hi Astronuts,

I joined AstroBin and posted my first image. Hope the link works:
https://www.astrobin.com/full/vsz056/0/?nc=user

This is an image taken with the Mach2 and 160EDF refractor, unguided over a period of 2 hours. I modeled a path that the object would take with 3 data points and let MaximDL take a set of images until the scope ran out of room and stopped at the limit. I'm shooting in very light polluted skies, the Moon was up and bright, so i was pleased that i was able to record some very faint stuff.

No guide scope was used, no field flattener, just the 160 refractor straight to the 8300 chip. Larger chips would need a flattener of course.

Rolando


 

Rolando that's great

how long was each exposure?

On Tue, Jun 2, 2020 at 2:14 PM uncarollo2 <chris1011@...> via groups.io <chris1011=aol.com@groups.io> wrote:
Hi Astronuts,

I joined AstroBin and posted my first image. Hope the link works:

This is an image taken with the Mach2 and 160EDF refractor, unguided over a period of 2 hours. I modeled a path that the object would take with 3 data points and let MaximDL take a set of images until the scope ran out of room and stopped at the limit. I'm shooting in very light polluted skies, the Moon was up and bright, so i was pleased that i was able to record some very faint stuff.

No guide scope was used, no field flattener, just the 160 refractor straight to the 8300 chip. Larger chips would need a flattener of course.

Rolando



--
Brian 



Brian Valente


Dean Jacobsen
 

Excellent!

Looking forward to the release of the new keypad software.
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Dominique Durand
 

Superb Rolando,the Mach2 is really made to relieve us of the guide.
I tested the 2nd evening for my Mach2 after a 35 point modeling of the 600 "poses on M109 ... with round stars as I had rarely succeeded with guide.


Roland Christen
 

10 minute subs x 12

I like to expose until the central part of the galaxy is near saturation, but does not exceed it. That way the core is not blown out and no detail is lost there.

Rolando



-----Original Message-----
From: Brian Valente <bvalente@...>
To: main@ap-gto.groups.io
Sent: Tue, Jun 2, 2020 4:24 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Rolando that's great

how long was each exposure?

On Tue, Jun 2, 2020 at 2:14 PM uncarollo2 <chris1011@...> via groups.io <chris1011=aol.com@groups.io> wrote:
Hi Astronuts,

I joined AstroBin and posted my first image. Hope the link works:

This is an image taken with the Mach2 and 160EDF refractor, unguided over a period of 2 hours. I modeled a path that the object would take with 3 data points and let MaximDL take a set of images until the scope ran out of room and stopped at the limit. I'm shooting in very light polluted skies, the Moon was up and bright, so i was pleased that i was able to record some very faint stuff.

No guide scope was used, no field flattener, just the 160 refractor straight to the 8300 chip. Larger chips would need a flattener of course.

Rolando


--
Brian 



Brian Valente


Cheng-Yang Tan
 

Hi Rolando,
   That's an interesting technique. I usually use 5 min subs. I'll try it out the next time.

cytan

On Tuesday, June 2, 2020, 04:49:48 PM CDT, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:


10 minute subs x 12

I like to expose until the central part of the galaxy is near saturation, but does not exceed it. That way the core is not blown out and no detail is lost there.

Rolando



-----Original Message-----
From: Brian Valente <bvalente@...>
To: main@ap-gto.groups.io
Sent: Tue, Jun 2, 2020 4:24 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Rolando that's great

how long was each exposure?

On Tue, Jun 2, 2020 at 2:14 PM uncarollo2 <chris1011@...> via groups.io <chris1011=aol.com@groups.io> wrote:
Hi Astronuts,

I joined AstroBin and posted my first image. Hope the link works:

This is an image taken with the Mach2 and 160EDF refractor, unguided over a period of 2 hours. I modeled a path that the object would take with 3 data points and let MaximDL take a set of images until the scope ran out of room and stopped at the limit. I'm shooting in very light polluted skies, the Moon was up and bright, so i was pleased that i was able to record some very faint stuff.

No guide scope was used, no field flattener, just the 160 refractor straight to the 8300 chip. Larger chips would need a flattener of course.

Rolando


--
Brian 



Brian Valente


Roland Christen
 

We have one more obscure bug to fix, and Liam and I have to finish the keypad instructions.

Rolando

-----Original Message-----
From: Dean Jacobsen <deanjacobsen@...>
To: main@ap-gto.groups.io
Sent: Tue, Jun 2, 2020 4:31 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Excellent!

Looking forward to the release of the new keypad software.
--
Dean Jacobsen
http://astrophoto.net/wp/ 
Image Gallery - http://astrophoto.net/wp/image-gallery/
Astrobin - https://www.astrobin.com/users/deanjacobsen/ 


Roland Christen
 

That is really nice to hear.

Thanks,

Rolando



-----Original Message-----
From: Dominique Durand via groups.io <dom33.durand@...>
To: main@ap-gto.groups.io
Sent: Tue, Jun 2, 2020 4:42 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Superb Rolando,the Mach2 is really made to relieve us of the guide.
I tested the 2nd evening for my Mach2 after a 35 point modeling of the 600 "poses on M109 ... with round stars as I had rarely succeeded with guide.


Roland Christen
 

I also use 5 min subs at times, especially when satellites go streaking across the field. That way I don't get every exposure with streaks. Until 11pm here i get satellite streaks in long exposures ~ 20 min or more, so it's not possible to get good data.

Rolando



-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Jun 2, 2020 4:51 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Hi Rolando,
   That's an interesting technique. I usually use 5 min subs. I'll try it out the next time.

cytan

On Tuesday, June 2, 2020, 04:49:48 PM CDT, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:


10 minute subs x 12

I like to expose until the central part of the galaxy is near saturation, but does not exceed it. That way the core is not blown out and no detail is lost there.

Rolando



-----Original Message-----
From: Brian Valente <bvalente@...>
To: main@ap-gto.groups.io
Sent: Tue, Jun 2, 2020 4:24 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Rolando that's great

how long was each exposure?

On Tue, Jun 2, 2020 at 2:14 PM uncarollo2 <chris1011@...> via groups.io <chris1011=aol.com@groups.io> wrote:
Hi Astronuts,

I joined AstroBin and posted my first image. Hope the link works:

This is an image taken with the Mach2 and 160EDF refractor, unguided over a period of 2 hours. I modeled a path that the object would take with 3 data points and let MaximDL take a set of images until the scope ran out of room and stopped at the limit. I'm shooting in very light polluted skies, the Moon was up and bright, so i was pleased that i was able to record some very faint stuff.

No guide scope was used, no field flattener, just the 160 refractor straight to the 8300 chip. Larger chips would need a flattener of course.

Rolando


--
Brian 



Brian Valente


dvjbaja
 

Just noting that there is vertical banding visible in the image. (and I realize this is just a test image).  Might be worth looking into when you want to take a "pretty picture". ;-)

jg  


Bill Long
 

I am also very pleased to see Roland on Astrobin. 😄 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of uncarollo2 <chris1011@...> via groups.io <chris1011@...>
Sent: Tuesday, June 2, 2020 2:56 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies
 
I also use 5 min subs at times, especially when satellites go streaking across the field. That way I don't get every exposure with streaks. Until 11pm here i get satellite streaks in long exposures ~ 20 min or more, so it's not possible to get good data.

Rolando



-----Original Message-----
From: Cheng-Yang Tan via groups.io <cytan299@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Tue, Jun 2, 2020 4:51 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Hi Rolando,
   That's an interesting technique. I usually use 5 min subs. I'll try it out the next time.

cytan

On Tuesday, June 2, 2020, 04:49:48 PM CDT, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:


10 minute subs x 12

I like to expose until the central part of the galaxy is near saturation, but does not exceed it. That way the core is not blown out and no detail is lost there.

Rolando



-----Original Message-----
From: Brian Valente <bvalente@...>
To: main@ap-gto.groups.io
Sent: Tue, Jun 2, 2020 4:24 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Rolando that's great

how long was each exposure?

On Tue, Jun 2, 2020 at 2:14 PM uncarollo2 <chris1011@...> via groups.io <chris1011=aol.com@groups.io> wrote:
Hi Astronuts,

I joined AstroBin and posted my first image. Hope the link works:

This is an image taken with the Mach2 and 160EDF refractor, unguided over a period of 2 hours. I modeled a path that the object would take with 3 data points and let MaximDL take a set of images until the scope ran out of room and stopped at the limit. I'm shooting in very light polluted skies, the Moon was up and bright, so i was pleased that i was able to record some very faint stuff.

No guide scope was used, no field flattener, just the 160 refractor straight to the 8300 chip. Larger chips would need a flattener of course.

Rolando


--
Brian 



Brian Valente


Stuart <stuart.j.heggie@...>
 

Most impressive Rolando!!!


On Tue, 2 Jun 2020 at 17:14, uncarollo2 <chris1011@...> via groups.io <chris1011=aol.com@groups.io> wrote:
Hi Astronuts,

I joined AstroBin and posted my first image. Hope the link works:

This is an image taken with the Mach2 and 160EDF refractor, unguided over a period of 2 hours. I modeled a path that the object would take with 3 data points and let MaximDL take a set of images until the scope ran out of room and stopped at the limit. I'm shooting in very light polluted skies, the Moon was up and bright, so i was pleased that i was able to record some very faint stuff.

No guide scope was used, no field flattener, just the 160 refractor straight to the 8300 chip. Larger chips would need a flattener of course.

Rolando


--

Stuart
http://www.astrofoto.ca/stuartheggie/


willsonjared
 

For me, this feature will be the difference between a Mach2 being, “cool, but don’t really see a reason to upgrade from my Mach1” and being, “Wow, that would make it easy to bring a system into the field without needing to guide!”  Well done.  I can now see myself replacing my Mach1 at some point in the future which is something I couldn’t have imagined when the Mach2 was announced.


Roland Christen
 

Besides the encoders eliminating PE, the Mach2 brings the ability to move the mount manually during visual sweeping of the skies without losing position. It also allows critical balance to be achieved without backing the worm off the wormwheel and possibly damaging the worm teeth in the process, if done wrong. The base of the mount has been widened for better stability. Internally the heavy shaft sits farther between the bearings for increased stability over the Mach1.

The absolute encoders are mapped so that the precision tracking and pointing is maintained over the entire 360 degree axis motion. Relative encoders can theoretically eliminate PE, but generally introduce sub-divisional error (SDE). Relative encoders cannot be mapped at the factory against a known standard lab encoder since they do not have individual distinct position information. So the tracking accuracy may contain no periodic error component, but will inevitably have large drift component due to encoder disc runout. The Renishaw RESA encoder system has some 64 million distinct positions which are carefully mapped in our initial test and setup routine here at AP. The data is then transferred to the CP5 where it is stored and used to provide precise tracking and positioning to the axes at every point in the rotation of the axes.

To sum up the Mach2:

Mount has clutches that allow precise balancing of the axes.

Clutches can be loosened for manual sweeping of the mount during visual observing with no loss of position.

The gearbox uses belt drive for quiet operation along with brushless microstepper motors

The motors are oversized to provide high torque, the belts are heavy duty.

Precision Absolute encoders eliminate periodic error during sidereal or custom tracking

The encoders are mapped over 360 degrees to provide precise positioning and tracking over the entire rotation

The mount base has been strengthened for lower vibration and better damping of heavy loads.

Modern feed-forward encoder control loop produces quick response to external forces and produces a stiffer mount

Both axes can be driven accurately at custom and variable rates for unguided imaging with modeling

Rolando






-----Original Message-----
From: willsonjared via groups.io <willsonjared@...>
To: main@ap-gto.groups.io
Sent: Thu, Jun 4, 2020 1:05 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

For me, this feature will be the difference between a Mach2 being, “cool, but don’t really see a reason to upgrade from my Mach1” and being, “Wow, that would make it easy to bring a system into the field without needing to guide!”  Well done.  I can now see myself replacing my Mach1 at some point in the future which is something I couldn’t have imagined when the Mach2 was announced.


DFisch
 

Rolando, how many of these features would be available to the 1100 after AE upgrade (notwithstanding the mechanical features).  How close would the similarities be on guiding and modeling .  Tom

On Jun 4, 2020, at 2:58 PM, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:

Besides the encoders eliminating PE, the Mach2 brings the ability to move the mount manually during visual sweeping of the skies without losing position. It also allows critical balance to be achieved without backing the worm off the wormwheel and possibly damaging the worm teeth in the process, if done wrong. The base of the mount has been widened for better stability. Internally the heavy shaft sits farther between the bearings for increased stability over the Mach1.

The absolute encoders are mapped so that the precision tracking and pointing is maintained over the entire 360 degree axis motion. Relative encoders can theoretically eliminate PE, but generally introduce sub-divisional error (SDE). Relative encoders cannot be mapped at the factory against a known standard lab encoder since they do not have individual distinct position information. So the tracking accuracy may contain no periodic error component, but will inevitably have large drift component due to encoder disc runout. The Renishaw RESA encoder system has some 64 million distinct positions which are carefully mapped in our initial test and setup routine here at AP. The data is then transferred to the CP5 where it is stored and used to provide precise tracking and positioning to the axes at every point in the rotation of the axes.

To sum up the Mach2:

Mount has clutches that allow precise balancing of the axes.

Clutches can be loosened for manual sweeping of the mount during visual observing with no loss of position.

The gearbox uses belt drive for quiet operation along with brushless microstepper motors

The motors are oversized to provide high torque, the belts are heavy duty.

Precision Absolute encoders eliminate periodic error during sidereal or custom tracking

The encoders are mapped over 360 degrees to provide precise positioning and tracking over the entire rotation

The mount base has been strengthened for lower vibration and better damping of heavy loads.

Modern feed-forward encoder control loop produces quick response to external forces and produces a stiffer mount

Both axes can be driven accurately at custom and variable rates for unguided imaging with modeling

Rolando






-----Original Message-----
From: willsonjared via groups.io <willsonjared@...>
To: main@ap-gto.groups.io
Sent: Thu, Jun 4, 2020 1:05 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

For me, this feature will be the difference between a Mach2 being, “cool, but don’t really see a reason to upgrade from my Mach1” and being, “Wow, that would make it easy to bring a system into the field without needing to guide!”  Well done.  I can now see myself replacing my Mach1 at some point in the future which is something I couldn’t have imagined when the Mach2 was announced.


Roland Christen
 

The 1100 AE is more accurate, heavier construction, larger gearwheel and has hollow axes so you can run your own cables. Although it has clutches, the mount will not keep track of pointing while they are loose and you move the scope manually.

The 1100 has precision spur gear reduction and high speed servo motors, not belts and microsteppers. Belts and microsteppers are only accurate to arc sec levels when combined with absolute encoders on the shafts. Precision spur gears and Swiss servo motors can provide smooth arc sec level tracking, without AE, when you have a good PE correction curve.

Speaking of inexpensive mounts with steppers and belt drives:
Microsteppers with belts are audibly quiet but mechanically noisy (precision gears are audibly noisy but mechanically smooth). Have you ever seen what the periodic error looks like with a microstepper running a belt drive? Do you think it is smooth and accurate? Would you like to see?

Rolando



-----Original Message-----
From: DFisch <manusfisch@...>
To: main@ap-gto.groups.io
Sent: Sun, May 31, 2020 2:49 am
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Rolando, how many of these features would be available to the 1100 after AE upgrade (notwithstanding the mechanical features).  How close would the similarities be on guiding and modeling .  Tom

On Jun 4, 2020, at 2:58 PM, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:

Besides the encoders eliminating PE, the Mach2 brings the ability to move the mount manually during visual sweeping of the skies without losing position. It also allows critical balance to be achieved without backing the worm off the wormwheel and possibly damaging the worm teeth in the process, if done wrong. The base of the mount has been widened for better stability. Internally the heavy shaft sits farther between the bearings for increased stability over the Mach1.

The absolute encoders are mapped so that the precision tracking and pointing is maintained over the entire 360 degree axis motion. Relative encoders can theoretically eliminate PE, but generally introduce sub-divisional error (SDE). Relative encoders cannot be mapped at the factory against a known standard lab encoder since they do not have individual distinct position information. So the tracking accuracy may contain no periodic error component, but will inevitably have large drift component due to encoder disc runout. The Renishaw RESA encoder system has some 64 million distinct positions which are carefully mapped in our initial test and setup routine here at AP. The data is then transferred to the CP5 where it is stored and used to provide precise tracking and positioning to the axes at every point in the rotation of the axes.

To sum up the Mach2:

Mount has clutches that allow precise balancing of the axes.

Clutches can be loosened for manual sweeping of the mount during visual observing with no loss of position.

The gearbox uses belt drive for quiet operation along with brushless microstepper motors

The motors are oversized to provide high torque, the belts are heavy duty.

Precision Absolute encoders eliminate periodic error during sidereal or custom tracking

The encoders are mapped over 360 degrees to provide precise positioning and tracking over the entire rotation

The mount base has been strengthened for lower vibration and better damping of heavy loads.

Modern feed-forward encoder control loop produces quick response to external forces and produces a stiffer mount

Both axes can be driven accurately at custom and variable rates for unguided imaging with modeling

Rolando






-----Original Message-----
From: willsonjared via groups.io <willsonjared@...>
To: main@ap-gto.groups.io
Sent: Thu, Jun 4, 2020 1:05 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

For me, this feature will be the difference between a Mach2 being, “cool, but don’t really see a reason to upgrade from my Mach1” and being, “Wow, that would make it easy to bring a system into the field without needing to guide!”  Well done.  I can now see myself replacing my Mach1 at some point in the future which is something I couldn’t have imagined when the Mach2 was announced.


 

>> Have you ever seen what the periodic error looks like with a microstepper running a belt drive? Do you think it is smooth and accurate? Would you like to see?

yes please! i would like to see

On Thu, Jun 4, 2020 at 1:46 PM uncarollo2 <chris1011@...> via groups.io <chris1011=aol.com@groups.io> wrote:
The 1100 AE is more accurate, heavier construction, larger gearwheel and has hollow axes so you can run your own cables. Although it has clutches, the mount will not keep track of pointing while they are loose and you move the scope manually.

The 1100 has precision spur gear reduction and high speed servo motors, not belts and microsteppers. Belts and microsteppers are only accurate to arc sec levels when combined with absolute encoders on the shafts. Precision spur gears and Swiss servo motors can provide smooth arc sec level tracking, without AE, when you have a good PE correction curve.

Speaking of inexpensive mounts with steppers and belt drives:
Microsteppers with belts are audibly quiet but mechanically noisy (precision gears are audibly noisy but mechanically smooth). Have you ever seen what the periodic error looks like with a microstepper running a belt drive? Do you think it is smooth and accurate? Would you like to see?

Rolando



-----Original Message-----
From: DFisch <manusfisch@...>
To: main@ap-gto.groups.io
Sent: Sun, May 31, 2020 2:49 am
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Rolando, how many of these features would be available to the 1100 after AE upgrade (notwithstanding the mechanical features).  How close would the similarities be on guiding and modeling .  Tom

On Jun 4, 2020, at 2:58 PM, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:

Besides the encoders eliminating PE, the Mach2 brings the ability to move the mount manually during visual sweeping of the skies without losing position. It also allows critical balance to be achieved without backing the worm off the wormwheel and possibly damaging the worm teeth in the process, if done wrong. The base of the mount has been widened for better stability. Internally the heavy shaft sits farther between the bearings for increased stability over the Mach1.

The absolute encoders are mapped so that the precision tracking and pointing is maintained over the entire 360 degree axis motion. Relative encoders can theoretically eliminate PE, but generally introduce sub-divisional error (SDE). Relative encoders cannot be mapped at the factory against a known standard lab encoder since they do not have individual distinct position information. So the tracking accuracy may contain no periodic error component, but will inevitably have large drift component due to encoder disc runout. The Renishaw RESA encoder system has some 64 million distinct positions which are carefully mapped in our initial test and setup routine here at AP. The data is then transferred to the CP5 where it is stored and used to provide precise tracking and positioning to the axes at every point in the rotation of the axes.

To sum up the Mach2:

Mount has clutches that allow precise balancing of the axes.

Clutches can be loosened for manual sweeping of the mount during visual observing with no loss of position.

The gearbox uses belt drive for quiet operation along with brushless microstepper motors

The motors are oversized to provide high torque, the belts are heavy duty.

Precision Absolute encoders eliminate periodic error during sidereal or custom tracking

The encoders are mapped over 360 degrees to provide precise positioning and tracking over the entire rotation

The mount base has been strengthened for lower vibration and better damping of heavy loads.

Modern feed-forward encoder control loop produces quick response to external forces and produces a stiffer mount

Both axes can be driven accurately at custom and variable rates for unguided imaging with modeling

Rolando






-----Original Message-----
From: willsonjared via groups.io <willsonjared@...>
To: main@ap-gto.groups.io
Sent: Thu, Jun 4, 2020 1:05 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

For me, this feature will be the difference between a Mach2 being, “cool, but don’t really see a reason to upgrade from my Mach1” and being, “Wow, that would make it easy to bring a system into the field without needing to guide!”  Well done.  I can now see myself replacing my Mach1 at some point in the future which is something I couldn’t have imagined when the Mach2 was announced.



--
Brian 



Brian Valente


Bill Long
 

+1 for this. Sounds interesting. 🙂 


From: main@ap-gto.groups.io <main@ap-gto.groups.io> on behalf of Brian Valente <bvalente@...>
Sent: Thursday, June 4, 2020 1:51 PM
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies
 
>> Have you ever seen what the periodic error looks like with a microstepper running a belt drive? Do you think it is smooth and accurate? Would you like to see?

yes please! i would like to see

On Thu, Jun 4, 2020 at 1:46 PM uncarollo2 <chris1011@...> via groups.io <chris1011=aol.com@groups.io> wrote:
The 1100 AE is more accurate, heavier construction, larger gearwheel and has hollow axes so you can run your own cables. Although it has clutches, the mount will not keep track of pointing while they are loose and you move the scope manually.

The 1100 has precision spur gear reduction and high speed servo motors, not belts and microsteppers. Belts and microsteppers are only accurate to arc sec levels when combined with absolute encoders on the shafts. Precision spur gears and Swiss servo motors can provide smooth arc sec level tracking, without AE, when you have a good PE correction curve.

Speaking of inexpensive mounts with steppers and belt drives:
Microsteppers with belts are audibly quiet but mechanically noisy (precision gears are audibly noisy but mechanically smooth). Have you ever seen what the periodic error looks like with a microstepper running a belt drive? Do you think it is smooth and accurate? Would you like to see?

Rolando



-----Original Message-----
From: DFisch <manusfisch@...>
To: main@ap-gto.groups.io
Sent: Sun, May 31, 2020 2:49 am
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Rolando, how many of these features would be available to the 1100 after AE upgrade (notwithstanding the mechanical features).  How close would the similarities be on guiding and modeling .  Tom

On Jun 4, 2020, at 2:58 PM, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:

Besides the encoders eliminating PE, the Mach2 brings the ability to move the mount manually during visual sweeping of the skies without losing position. It also allows critical balance to be achieved without backing the worm off the wormwheel and possibly damaging the worm teeth in the process, if done wrong. The base of the mount has been widened for better stability. Internally the heavy shaft sits farther between the bearings for increased stability over the Mach1.

The absolute encoders are mapped so that the precision tracking and pointing is maintained over the entire 360 degree axis motion. Relative encoders can theoretically eliminate PE, but generally introduce sub-divisional error (SDE). Relative encoders cannot be mapped at the factory against a known standard lab encoder since they do not have individual distinct position information. So the tracking accuracy may contain no periodic error component, but will inevitably have large drift component due to encoder disc runout. The Renishaw RESA encoder system has some 64 million distinct positions which are carefully mapped in our initial test and setup routine here at AP. The data is then transferred to the CP5 where it is stored and used to provide precise tracking and positioning to the axes at every point in the rotation of the axes.

To sum up the Mach2:

Mount has clutches that allow precise balancing of the axes.

Clutches can be loosened for manual sweeping of the mount during visual observing with no loss of position.

The gearbox uses belt drive for quiet operation along with brushless microstepper motors

The motors are oversized to provide high torque, the belts are heavy duty.

Precision Absolute encoders eliminate periodic error during sidereal or custom tracking

The encoders are mapped over 360 degrees to provide precise positioning and tracking over the entire rotation

The mount base has been strengthened for lower vibration and better damping of heavy loads.

Modern feed-forward encoder control loop produces quick response to external forces and produces a stiffer mount

Both axes can be driven accurately at custom and variable rates for unguided imaging with modeling

Rolando






-----Original Message-----
From: willsonjared via groups.io <willsonjared@...>
To: main@ap-gto.groups.io
Sent: Thu, Jun 4, 2020 1:05 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

For me, this feature will be the difference between a Mach2 being, “cool, but don’t really see a reason to upgrade from my Mach1” and being, “Wow, that would make it easy to bring a system into the field without needing to guide!”  Well done.  I can now see myself replacing my Mach1 at some point in the future which is something I couldn’t have imagined when the Mach2 was announced.



--
Brian 



Brian Valente


DFisch
 

Rolando, thanks for the instruction.  i have an 1100 mount and lost the step in my thinking where disengaging the clutches loses the encoder feedback as to where they are constructed and installed on the mount.  When i was imagining "no lost position” with an upgrade to my already excellent 1100 to AE i forgot the fundamental difference of the new design.  no harm in dreaming.   i love your analogic comparison of the difference in the type of “noise” generated by the two types of drive systems. The differences in the mach2 with AE vs. 1100 AE wont be lost on me again.  Tom 

On Jun 4, 2020, at 4:46 PM, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:

The 1100 AE is more accurate, heavier construction, larger gearwheel and has hollow axes so you can run your own cables. Although it has clutches, the mount will not keep track of pointing while they are loose and you move the scope manually.

The 1100 has precision spur gear reduction and high speed servo motors, not belts and microsteppers. Belts and microsteppers are only accurate to arc sec levels when combined with absolute encoders on the shafts. Precision spur gears and Swiss servo motors can provide smooth arc sec level tracking, without AE, when you have a good PE correction curve.

Speaking of inexpensive mounts with steppers and belt drives:
Microsteppers with belts are audibly quiet but mechanically noisy (precision gears are audibly noisy but mechanically smooth). Have you ever seen what the periodic error looks like with a microstepper running a belt drive? Do you think it is smooth and accurate? Would you like to see?

Rolando



-----Original Message-----
From: DFisch <manusfisch@...>
To: main@ap-gto.groups.io
Sent: Sun, May 31, 2020 2:49 am
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

Rolando, how many of these features would be available to the 1100 after AE upgrade (notwithstanding the mechanical features).  How close would the similarities be on guiding and modeling .  Tom

On Jun 4, 2020, at 2:58 PM, uncarollo2 <chris1011@...> via groups.io <chris1011@...> wrote:

Besides the encoders eliminating PE, the Mach2 brings the ability to move the mount manually during visual sweeping of the skies without losing position. It also allows critical balance to be achieved without backing the worm off the wormwheel and possibly damaging the worm teeth in the process, if done wrong. The base of the mount has been widened for better stability. Internally the heavy shaft sits farther between the bearings for increased stability over the Mach1.

The absolute encoders are mapped so that the precision tracking and pointing is maintained over the entire 360 degree axis motion. Relative encoders can theoretically eliminate PE, but generally introduce sub-divisional error (SDE). Relative encoders cannot be mapped at the factory against a known standard lab encoder since they do not have individual distinct position information. So the tracking accuracy may contain no periodic error component, but will inevitably have large drift component due to encoder disc runout. The Renishaw RESA encoder system has some 64 million distinct positions which are carefully mapped in our initial test and setup routine here at AP. The data is then transferred to the CP5 where it is stored and used to provide precise tracking and positioning to the axes at every point in the rotation of the axes.

To sum up the Mach2:

Mount has clutches that allow precise balancing of the axes.

Clutches can be loosened for manual sweeping of the mount during visual observing with no loss of position.

The gearbox uses belt drive for quiet operation along with brushless microstepper motors

The motors are oversized to provide high torque, the belts are heavy duty.

Precision Absolute encoders eliminate periodic error during sidereal or custom tracking

The encoders are mapped over 360 degrees to provide precise positioning and tracking over the entire rotation

The mount base has been strengthened for lower vibration and better damping of heavy loads.

Modern feed-forward encoder control loop produces quick response to external forces and produces a stiffer mount

Both axes can be driven accurately at custom and variable rates for unguided imaging with modeling

Rolando






-----Original Message-----
From: willsonjared via groups.io <willsonjared@...>
To: main@ap-gto.groups.io
Sent: Thu, Jun 4, 2020 1:05 pm
Subject: Re: [ap-gto] NGC5371 and surrounding galaxies

For me, this feature will be the difference between a Mach2 being, “cool, but don’t really see a reason to upgrade from my Mach1” and being, “Wow, that would make it easy to bring a system into the field without needing to guide!”  Well done.  I can now see myself replacing my Mach1 at some point in the future which is something I couldn’t have imagined when the Mach2 was announced.



Roland Christen
 


yes please! i would like to see

Ok, see below. Sorry for the poor quality screen shots. I took them with my camera aimed at the screen ;^)).

Top image is the raw periodic error of a typical microstepper driving a precision worm. You might think the worm is not great, but the reality is that the two pulleys have runout and produce the majority of the large scale periodic error. The worm itself actually has only about 2 arc sec error. The rest is caused by the commercial pulleys which have a fair amount of runout. This is basically what you get in almost all imported non-encoder mounts that use belts and microsteppers.

The plot is taken at 100msec sample rate so you can see what is really happening during a typical worm cycle. Normally when you see a PE curve, the sample rate is 10 times slower, so you don't see the fast moving errors on PE data sheets.

The real issue is not the large scale PE, which can be handled by guiding (as long as it is slow moving and not too large an excursion). It is the fast moving errors at the 1 arc sec level that cause problems for guiders. The second plot shows in detail that microsteppers with belts have two fast moving errors. The belt teeth cause a ripple every few seconds (in this case once every 12 seconds at approx 1 arc sec P-P). If your guiding cadence is fast enough you might be able to guide it out successfully. However, if your guide rate approaches once every 3 - 4 seconds, you will see a residual error that modulates with time.

The faster moving error repeats every 2 seconds with another 1 arc-sec P-P error. This one cannot be easily guided out because the guider is always a step behind and can actually amplify this motion. The error is caused by the stepper motor itself which has 5% angle variation for each winding step point. If your camera pixel scale is 2 - 4 arc sec per pixel, you may not see these kinds of errors. If your guider is exposing at 2 - 3 seconds, the guide graph will average out the tiny fast motions and will record perhaps very low rms values. However, the stars that you are recording on your imaging camera are doing this tiny back and forth dance in RA and slightly smearing the resolution of your image.

The third graph below shows how the absolute encoder tames all three errors.