Date   

Re: Tracking and guiding with and without encoders - Part2

Ray Gralak
 

The logs should be from the same setup, not two different setups.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Tuesday, September 17, 2019 10:36 AM
To: ap-gto@...
Subject: RE: [ap-gto] Re: Tracking and guiding with and without encoders - Part2



I forgot I sold my duplicate ASI1600 last week, so the two rigs are identical except for the cameras. One will use
an ASI1600 and the other an ASI183.


Re: Tracking and guiding with and without encoders - Part2

Roland Christen
 

You will notice improvement with long focal lengths in good seeing. Otherwise you are limited by pixel resolution and atmospheric seeing.

Using the 180F9 refractor I was getting 1.2 to 1.3 arc sec FWHM all night during good seeing. The mount was guiding in both axes at 0.1 to 0.13 rms. I don't think that this would be possible with the non-encoder version of this mount - the Mach1. In our Chile observatory (1600 encoder mount) at LasCampanas we measured FWHM of 0.9 arc sec with the 305F8 Mak-Cass astrograph when we were setting it up.

As I indicated before, the Mach2 doesn't really work without the axis shaft encoders, just like your mount doesn't really work without the motor shaft encoders. Every decent mount has to have encoders somewhere, either on the motor shaft or on the axis shaft. The feedback from these encoders provides loop control and steady tracking rates. If the encoder is on the motor shaft then it does not account for errors in the geartrain. If it's on the output shaft then all errors are accounted for except for the encoder itself. Since we are opting to use high accuracy encoders on the output shaft, the errors are very very small, almost 5 times smaller than the best you can do with worm and spur gear reduction, even accounting for the use of PEM. You are then only limited by the atmosphere and your scope/camera resolution.

The encoders also provide a number of other benefits that people have wanted all along, so we are advancing the technology and raising the bar. The Mach2 is a very effective mount for high performing scopes and can handle larger loads better than its predecessor.

Rolando



-----Original Message-----
From: badgerz49@... [ap-gto]
To: ap-gto
Sent: Tue, Sep 17, 2019 11:34 am
Subject: Re: [ap-gto] Re: Tracking and guiding with and without encoders - Part2



Roland - so you are saying Total RMS will improve with encoders.  Back to the original question; how much improvement is there in Total RMS for guided imaging with typical 2-3 second guide intervals?

In limited testing I haven't noticed any improvement in Total RMS with PEC on vs. off, which is why I have doubts encoders will improve Total RMS much, if any.  That's with an excellent PEC curve that almost eliminated PE.  Seeing seems to be the limiting factor.  Fast oscillations, backlash, and PE are negligible.

Chad



Re: Tracking and guiding with and without encoders - Part2

Ray Gralak
 

Chad,

I ask because my experience has not been the same as you claim. I provided you with test results showing visible and measurable differences in FWHM and stellar eccentricity. The very least you can do is to provide guide logs that show no measurable difference in RMS when pec is enabled versus disabled. Please feel free to provide the logs alone. If they are phd2 logs my log viewer app can detect the moves and reconstruct periodic error to confirm pec was disabled in one of the logs (and thus a proper comparison).

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Tuesday, September 17, 2019 10:25 AM
To: ap-gto@...
Subject: RE: [ap-gto] Re: Tracking and guiding with and without encoders - Part2



Ray, I have guide logs but the AP ASCOM driver Logs folders are empty. I don't recall unchecking the "Enable
Debug Log" option, so maybe it's unchecked by default. It wasn't checked on either of the laptops for my AP
mounts.

I shouldn't have to do it, but I'm happy to run a complete test of guided Total RMS with PEC enabled vs. disabled
and share the results. I have identical AP1100 and identical OTA/Imaging trains which get total RMS almost
exactly in sync with each other. This acts as a control against variations in seeing being the cause of (non)
differences with PEC on/off. I will also show in PEMPro that my PEC curve almost completely eliminates PE. I'll
do it tonight if it's clear.

Chad



Re: Tracking and guiding with and without encoders - Part2

Chad A
 

I forgot I sold my duplicate ASI1600 last week, so the two rigs are identical except for the cameras.  One will use an ASI1600 and the other an ASI183.


Re: Tracking and guiding with and without encoders - Part2

Chad A
 

Ray, I have guide logs but the AP ASCOM driver Logs folders are empty.  I don't recall unchecking the "Enable Debug Log" option, so maybe it's unchecked by default.  It wasn't checked on either of the laptops for my AP mounts.

I shouldn't have to do it, but I'm happy to run a complete test of guided Total RMS with PEC enabled vs. disabled and share the results.  I have identical AP1100 and identical OTA/Imaging trains which get total RMS almost exactly in sync with each other.  This acts as a control against variations in seeing being the cause of (non) differences with PEC on/off.  I will also show in PEMPro that my PEC curve almost completely eliminates PE.  I'll do it tonight if it's clear.

Chad


Re: Tracking and guiding with and without encoders - Part2

Ray Gralak
 

Hi Chad,

Would you post some guide logs with pec enabled and not? Also include your ap v2 ascom driver logs.

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Tuesday, September 17, 2019 8:54 AM
To: ap-gto@...
Subject: Re: [ap-gto] Re: Tracking and guiding with and without encoders - Part2



Roland - so you are saying Total RMS will improve with encoders. Back to the original question; how much
improvement is there in Total RMS for guided imaging with typical 2-3 second guide intervals?


In limited testing I haven't noticed any improvement in Total RMS with PEC on vs. off, which is why I have doubts
encoders will improve Total RMS much, if any. That's with an excellent PEC curve that almost eliminated PE.
Seeing seems to be the limiting factor. Fast oscillations, backlash, and PE are negligible.


Chad


Re: SGP/APCC meridian limits vs. Homing/limits

rob
 

the way i have this configured is that i have a linear 'surface' defined in the meridian limit window which puts the meridian 45 minutes past the real meridian. originally i had the action set to "stop tracking" but i found that sometimes PHD2 might send a command to the mount after the limit was reached, resulting in the mount trying to start tracking again. so for a while i had it set to "park mount" but eventually i decided that if i set it to "flip mount" that perhaps SGP could recover from reaching the meridian limit. but ever since ray implemented the flip offset, this has never happened.

anyway, in the "fip offset" box i have entered 40 mins. i think what this does is tell SGP that its flip point should be 5 minutes past the real meridian (45-5), which gives 40 minutes for SGP to finish the current exposure and peform the flip. since i use 30 min exposures at maximum, this seems to work fine.

i'm not sure what would happen if i had a more complex meridian surface - say for instance if there were some areas that defined a 35 minute meridian delay. in theory that would ask SGP to flip 5 minutes before the meridian, but my understanding is that SGP won't support an early flip point on an AP mount because there are some missing methods in the ASCOM driver that they want to see. not sure what SGP does in this case; maybe it just clamps the meridian delay to 0. but then the effective offset is reduced.

rob


Re: Tracking and guiding with and without encoders - Part2

Chad A
 

Roland - so you are saying Total RMS will improve with encoders.  Back to the original question; how much improvement is there in Total RMS for guided imaging with typical 2-3 second guide intervals?

In limited testing I haven't noticed any improvement in Total RMS with PEC on vs. off, which is why I have doubts encoders will improve Total RMS much, if any.  That's with an excellent PEC curve that almost eliminated PE.  Seeing seems to be the limiting factor.  Fast oscillations, backlash, and PE are negligible.

Chad


Re: Tracking and guiding with and without encoders - Part2

Roland Christen
 


It seems you're not claiming guiding results, particularly Total RMS, will be improved with encoders. 
Yes, for sure guiding results will improve with the encoders. Dec response is instant, zero backlash. RA periodic error goes away, so no PE curve is required. Makes long term adjustment, tweaking, maintenance negligible, especially for remote mounts. RA guiding becomes relatively easy since you don't have to guide at rapid rates. You can take longer guide exposures without having the guide star wander due to short term tracking errors. The Mach2 tracks measurably better than the Mach1 for sure. By a factor of 2 on good nights. And even on poor nights there is less wander especially in the Dec axis.

Rolando


-----Original Message-----
From: badgerz49@... [ap-gto]
To: ap-gto
Sent: Tue, Sep 17, 2019 9:11 am
Subject: Re: [ap-gto] Re: Tracking and guiding with and without encoders - Part2



Roland,

It seems you're not claiming guiding results, particularly Total RMS, will be improved with encoders.  That's what I wanted to know.

It's never been in doubt whether encoders remove fast oscillations.  The oscillations in your graph are very small over a typical 2-3 second guide interval.  Whether they're detectable in guided images is a different topic.  I don't know what the seeing threshold is to notice them but I image it's beyond what most/all of us will ever have.

Chad



Re: Tracking and guiding with and without encoders - Part2

Chad A
 

Ray,

Yes, comparing FWHM seems like a good way to quantify the difference.  Rapid changes in seeing might make it difficult to test properly.  Any difference in results should be statistically confirmed over many samples and repeatable.  The test would be:

Guided encoder off FWHM vs. 1 second FWHM

against

Guided encoder on for same duration vs. 1 second FWHM

Chad







Re: Tracking and guiding with and without encoders - Part2

Ray Gralak
 

Hi Chad,

RMS guide error is the wrong measurement because it depends on the sampling of autoguider moves.

What you want to compare is average stellar FWHM and eccentricity of non-saturated stars in images. The image integrates light over the entire duration of an image and is the way to best determine guide quality. You want to compare the guided image's FWHM and eccentricity to those values in a very short duration image (e.g. 1 second duration).

-Ray Gralak
Author of APCC (Astro-Physics Command Center): http://www.astro-physics.com/index.htm?products/accessories/software/apcc/apcc
Author of PEMPro V3: https://www.ccdware.com
Author of Astro-Physics V2 ASCOM Driver: https://www.siriusimaging.com/apdriver

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...]
Sent: Tuesday, September 17, 2019 7:00 AM
To: ap-gto@...
Subject: Re: [ap-gto] Re: Tracking and guiding with and without encoders - Part2



Roland,


It seems you're not claiming guiding results, particularly Total RMS, will be improved with encoders. That's what I
wanted to know.

It's never been in doubt whether encoders remove fast oscillations. The oscillations in your graph are very small
over a typical 2-3 second guide interval. Whether they're detectable in guided images is a different topic. I don't
know what the seeing threshold is to notice them but I image it's beyond what most/all of us will ever have.


Chad


Re: Tracking and guiding with and without encoders - Part2

Chad A
 

Roland,

It seems you're not claiming guiding results, particularly Total RMS, will be improved with encoders.  That's what I wanted to know.

It's never been in doubt whether encoders remove fast oscillations.  The oscillations in your graph are very small over a typical 2-3 second guide interval.  Whether they're detectable in guided images is a different topic.  I don't know what the seeing threshold is to notice them but I image it's beyond what most/all of us will ever have.

Chad


Re: New file uploaded to ap-gto

Bill Long
 

That image leaves no doubt. 


From: ap-gto@... Sent: Monday, September 16, 2019 3:17 PM
To: ap-gto@...
Subject: [ap-gto] New file uploaded to ap-gto
 
 

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ap-gto
group.

File : /Mach2 Dual Encoder Guided Imaging/TrackingComparison.jpg
Uploaded by : uncarollo2
Description : Encoder on vs encoder off - tracking test

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ap-gto/files/Mach2%20Dual%20Encoder%20Guided%20Imaging/TrackingComparison.jpg

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

Regards,

uncarollo2


New file uploaded to ap-gto

ap-gto@...
 

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ap-gto
group.

File : /Mach2 Dual Encoder Guided Imaging/TrackingResponse.jpg
Uploaded by : uncarollo2 <chris1011@...>
Description : Mach 2 tracking response with encoders on. 0.5 sec sec move commands sent at various intervals.

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ap-gto/files/Mach2%20Dual%20Encoder%20Guided%20Imaging/TrackingResponse.jpg

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

Regards,

uncarollo2 <chris1011@...>


New file uploaded to ap-gto

ap-gto@...
 

Hello,

This email message is a notification to let you know that
a file has been uploaded to the Files area of the ap-gto
group.

File : /Mach2 Dual Encoder Guided Imaging/TrackingComparison.jpg
Uploaded by : uncarollo2 <chris1011@...>
Description : Encoder on vs encoder off - tracking test

You can access this file at the URL:
https://groups.yahoo.com/neo/groups/ap-gto/files/Mach2%20Dual%20Encoder%20Guided%20Imaging/TrackingComparison.jpg

To learn more about file sharing for your group, please visit:
https://help.yahoo.com/kb/index?page=content&y=PROD_GRPS&locale=en_US&id=SLN15398

Regards,

uncarollo2 <chris1011@...>


Re: Using the GTO keypad with the Mach2

Roland Christen
 

We will always have a full functioning keypad - the one we sell now. I use it almost always, even if I am imaging with other software.

Rolando



-----Original Message-----
From: mike.hambrick@... [ap-gto]
To: ap-gto
Sent: Mon, Sep 16, 2019 4:43 pm
Subject: Re: [ap-gto] Using the GTO keypad with the Mach2



Not everyone uses just a PC for imaging. I still like having a fully functional keypad


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        "chris1011@... [ap-gto]"
To:        ap-gto@...
Date:        09/14/2019 07:04 PM
Subject:        Re: [ap-gto] Using the GTO keypad with the Mach2
Sent by:        ap-gto@...




 
What we do need is a keypad we can see during the day when we're doing maintenance stuff.
I hear you. We actually are thinking of adding a minimalist keypad with Oleg screen that shows up in the daytime. One of our customers developed one and it is really nice. We just have to work out some things, but like you i do want this also.

Rolando


-----Original Message-----
From: 'Greg Salyer' astronutcase@... [ap-gto]
To: ap-gto
Sent: Sat, Sep 14, 2019 5:45 pm
Subject: RE: [ap-gto] Using the GTO keypad with the Mach2



Rolando, I don't mean to start anything, but most imagers have their mount connected to a PC and therefore don't need the keypad - at least at night. What we do need is a keypad we can see during the day when we're doing maintenance stuff. Your keypad is great but only at night. During the day it's a real pain. Every time I'm forced to use it I keep thinking of the easy to read in the daylight keypad on the cheap mount I use for visual stuff. Will we ever see an AP keypad usable during the day?
 
Greg
 
From: ap-gto@... [mailto:ap-gto@...]
Sent:
Saturday, September 14, 2019 5:47 PM
To:
ap-gto@...
Subject:
Re: [ap-gto] Using the GTO keypad with the Mach2

 
 
Nothing has changed on the keypad physically. Some of the buttons may change function. We don't have a final software set yet. We are adding in some things that will be very useful to imagers.
 
Rolando
 
 
 






Re: Using the GTO keypad with the Mach2

mike.hambrick@...
 

Not everyone uses just a PC for imaging. I still like having a fully functional keypad


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        "chris1011@... [ap-gto]" <ap-gto@...>
To:        ap-gto@...
Date:        09/14/2019 07:04 PM
Subject:        Re: [ap-gto] Using the GTO keypad with the Mach2
Sent by:        ap-gto@...




 

What we do need is a keypad we can see during the day when we're doing maintenance stuff.
I hear you. We actually are thinking of adding a minimalist keypad with Oleg screen that shows up in the daytime. One of our customers developed one and it is really nice. We just have to work out some things, but like you i do want this also.

Rolando


-----Original Message-----
From: 'Greg Salyer' astronutcase@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Sat, Sep 14, 2019 5:45 pm
Subject: RE: [ap-gto] Using the GTO keypad with the Mach2



Rolando, I don't mean to start anything, but most imagers have their mount connected to a PC and therefore don't need the keypad - at least at night. What we do need is a keypad we can see during the day when we're doing maintenance stuff. Your keypad is great but only at night. During the day it's a real pain. Every time I'm forced to use it I keep thinking of the easy to read in the daylight keypad on the cheap mount I use for visual stuff. Will we ever see an AP keypad usable during the day?
 
Greg
 
From: ap-gto@... [mailto:ap-gto@...]
Sent:
Saturday, September 14, 2019 5:47 PM
To:
ap-gto@...
Subject:
Re: [ap-gto] Using the GTO keypad with the Mach2

 
 
Nothing has changed on the keypad physically. Some of the buttons may change function. We don't have a final software set yet. We are adding in some things that will be very useful to imagers.
 
Rolando
 
 
 




Re: Tracking and guiding with and without encoders - Part2

Roland Christen
 

You are mixing apples and oranges. No wonder there is so much confusion. When you do 2 to 4 second guide exposures you are certainly not going to see very fast RA oscillations in the guide data. These oscillations happen quickly and can only be seen when you actually look at a star at rates faster than a guider can record. In my graphs I used sample rates of 100msec. You can do this with video on a small guide camera, but not at normal guide sample rates. Therefore all mounts can bury small fluctuation in RA tracking rates simply because they do not show up at long integration times.
If you don't know what these oscillations look like, here is one of many examples:https://www.cloudynights.com/topic/676345-cem-60ec-tracking-oscillations/

In this particular case it shows up at long focal lengths and is completely buried in the tracking graph when using 3  - 4 second integration times. Even though the guide chart shows maybe sub-arc sec guiding, the stars with that focal length are always a bit oval due to these p-p variations. And again, a belt drive isn't what does this, it's a microstepper motor without shaft encoder that can produce these fast moving oscillations. No amount of guiding can eliminate these.

Also, your seeing in both your examples is not good, average maybe for your skies, but we have to build mounts that can perform their best at sites that have excellent seeing without introducing mount tracking errors that would spoil the best results that could be obtained. This guiding graph (below) is what I would want the mount to achieve under good seeing, which in our case happens maybe once per month, but in places like Tuscon may happen every clear night. And that's taken at fairly long focal length with a long refractor:

-----Original Message-----
From: badgerz49@... [ap-gto] <ap-gto@...>
To: ap-gto <ap-gto@...>
Sent: Mon, Sep 16, 2019 3:13 pm
Subject: Re: [ap-gto] Re: Tracking and guiding with and without encoders - Part2

#yiv2559891291 #yiv2559891291 -- #yiv2559891291 .yiv2559891291ygrp-photo-title{ clear:both;font-size:smaller;min-height:15px;overflow:hidden;text-align:center;width:75px;} #yiv2559891291 div.yiv2559891291ygrp-photo{ background-position:center;background-repeat:no-repeat;background-color:white;border:1px solid black;min-height:62px;width:62px;} #yiv2559891291 div.yiv2559891291photo-title a, #yiv2559891291 div.yiv2559891291photo-title a:active, #yiv2559891291 div.yiv2559891291photo-title a:hover, #yiv2559891291 div.yiv2559891291photo-title a:visited { text-decoration:none; } #yiv2559891291 div.yiv2559891291attach-table div.yiv2559891291attach-row { clear:both;} #yiv2559891291 div.yiv2559891291attach-table div.yiv2559891291attach-row div { float:left;} #yiv2559891291 p { clear:both;padding:15px 0 3px 0;overflow:hidden;} #yiv2559891291 div.yiv2559891291ygrp-file { width:30px;} #yiv2559891291 div.yiv2559891291attach-table div.yiv2559891291attach-row div div a { text-decoration:none;} #yiv2559891291 div.yiv2559891291attach-table div.yiv2559891291attach-row div div span { font-weight:normal;} #yiv2559891291 div.yiv2559891291ygrp-file-title { font-weight:bold;} #yiv2559891291 #yiv2559891291 #yiv2559891291 #yiv2559891291 -- #yiv2559891291ygrp-mkp { border:1px solid #d8d8d8;font-family:Arial;margin:10px 0;padding:0 10px;} #yiv2559891291 #yiv2559891291ygrp-mkp hr { border:1px solid #d8d8d8;} #yiv2559891291 #yiv2559891291ygrp-mkp #yiv2559891291hd { color:#628c2a;font-size:85%;font-weight:700;line-height:122%;margin:10px 0;} #yiv2559891291 #yiv2559891291ygrp-mkp #yiv2559891291ads { margin-bottom:10px;} #yiv2559891291 #yiv2559891291ygrp-mkp .yiv2559891291ad { padding:0 0;} #yiv2559891291 #yiv2559891291ygrp-mkp .yiv2559891291ad p { margin:0;} #yiv2559891291 #yiv2559891291ygrp-mkp .yiv2559891291ad a { color:#0000ff;text-decoration:none;} #yiv2559891291

Roland,
P-P excursions are rare even with my belt-driven Atlas Pro.  Here's an image of guiding with two AP1100s and an Atlas Pro (top left) all at the same time with PEC disabled.  Excursions above 1" are infrequent (approx. 1/100 samples) and they're quickly guided out by PHD2.  Virtually none go above 1.5".  Total RMS is usually around .3" but seeing was mediocre this night.  
https://imgur.com/a/RDhtTaI

A PHD2 test of encoders vs. non-encoders would show excursions in the Target window.   Encoders should instantly remove excursions but when guiding are they really necessary and do they make a difference in the final result?  Maybe the belt-driven Mach 2 is a different story as you've noted.
Chad


Re: Tracking and guiding with and without encoders - Part2

Chad A
 

Roland,

P-P excursions are rare even with my belt-driven Atlas Pro.  Here's an image of guiding with two AP1100s and an Atlas Pro (top left) all at the same time with PEC disabled.  Excursions above 1" are infrequent (approx. 1/100 samples) and they're quickly guided out by PHD2.  Virtually none go above 1.5".  Total RMS is usually around .3" but seeing was mediocre this night.  


A PHD2 test of encoders vs. non-encoders would show excursions in the Target window.   Encoders should instantly remove excursions but when guiding are they really necessary and do they make a difference in the final result?  Maybe the belt-driven Mach 2 is a different story as you've noted.

Chad



Re: Tracking and guiding with and without encoders - Part2

Rick Socarras
 

Thankyou!

Rick