Imaging tonight with Mach2 at 5 below zero


Roland Christen
 

Yes, it's bitterly cold tonight, but very clear here in the Midwest. -5 degrees F and heading to -15. Mount's running like a champ, slewing and tracking smoothly with high accuracy and no muss or fuss. 10" Mak-Cass astrograph shooting my favorite deep sky objects. Guiding at between 0.1 and 0.15 arc sec rms at 1600mm focal length.
I Love this mount Heart Eyes

Rolando

--
Roland Christen
Astro-Physics


Emilio J. Robau, P.E.
 

The temperature I can pass on, but don't rub it in.  We love the Mach 2 also, and is why you need to keep producing them!

Clear skies!  Warm Temperatures


AaronW
 

I am a new owner of a Mach2 and am extremely happy with it (my first ever mount, actually!).  However, I never get anything close to 0.15 arc sec rms.  I have not yet attempted to build a pointing model and am simply guiding with PHD2.  But perhaps my PHD settings are not what they should be.  

I am imaging exclusively in narrowband in Bortle 7/8 skies, and seeing conditions vary from night to night, but even under “above average” seeing conditions (as defined by the app “Astrospheric”), the best I can get is 0.3 arc sec total rms (think I was at 0.25 for a few hours one night).  

I always image at a focal length of between 730 - 910mm, I polar align easily with SharpCap and am always within just a few arc seconds of error), and my PHD2 settings are as follows:

RA Agr: 70
Hys: 10
MnMo: 0.24
DEC: Agr: 100
MnMo: 0.24
Scope: Mx RA: 2500
Mx DEC: 2500

Guiding exposures typically looping at 4 seconds and multi-star guiding is always enabled.  

Any suggestions about how to optimize are welcome!

Best,
Aaron

On Jan 20, 2022, at 8:14 PM, Roland Christen via groups.io <chris1011@...> wrote:


Yes, it's bitterly cold tonight, but very clear here in the Midwest. -5 degrees F and heading to -15. Mount's running like a champ, slewing and tracking smoothly with high accuracy and no muss or fuss. 10" Mak-Cass astrograph shooting my favorite deep sky objects. Guiding at between 0.1 and 0.15 arc sec rms at 1600mm focal length.
I Love this mount Heart Eyes

Rolando

--
Roland Christen
Astro-Physics


Clayton Yendrey
 
Edited

Your best bet on tuning recommendations will be to post your log files to the PHD2 support group - the zip tool is in PHD2 and the link to the support forum is on their website.  To put some perspective on this, your current guide performance as indicated in your post is excellent, so you're chasing a difference that may not be visible/provide any tangible improvements unless you have a very long focal length OTA (>2000mm).  Being a little OCD myself, I've gone down that rabbit hole a few times only to be given a reality check by PHD2 Support when they pointed out that I was seeing guide performance better than the capability of most the mounts in use by amateurs.

If there is an issue with your PHD2 setup, I'd guess that default tuning parameters are too aggressive for a premium mount like the Mach2.  I have a Software Bisque MyT and it does not do well with the default settings in PHD2, doing best with aggression dialed back 10 - 20 points or so from the default.  Have you run a solid base line on your mount with PHD2 (PHD2 support is going to ask/request that)?  With encoders you should not have DEC backlash compensation enabled in the guide algorithm.

Instructions are on their website on how to run / create a baseline log session; you'll want to make sure you have a good/excellent  polar alignment,

Calibrate, then Run Guide assistant (all at or at least within 10dg of DEC 0, starting just west of the Meridian to insure a flip isn't required during the process.

Run a short 2- 5 minute guide session (until the Polar Alignment error indication stabilizes)

Update PHD2 with the setting recommendations from Guide Assistant, then run Guide Assistant again.  PHD2 Support likes to see 20 minutes, give or take on the longer session.  I usually go for two worm cycles when I'm doing this part, but you want at least one IMO.  Update the PHD2 settings again with the 'tweaked' recommendations from Guide Assistant.  Guide Assistant may also make some recommendations concerning which guide algorithm to use on either the RA or DEC.  On my MyT, it prefers the Low Pass 2 for DEC, YMMV.

As a non-encoder mount I'm happy to say that my MyT routinely gets .25"-.5" Total RMS dependent on seeing (I have Bortle 4 skies).  The mount is on a pier mounting with an excellent PA, a large pointing model, and with the ProTrack correcting algorithm turned on that having the TPoint model enables.  The A-P mount is no different, the encoders are not a magic pointing wand - you have to have the foundation steps completed to get the performance that mount can provide.

In Bortle 7/8 skies, seeing is pretty much always going to influence your guiding since your guide scope ( or if you are configured with an OAG) are not seeing the same filtered view as the imaging camera but rather full spectrum.  I think the guide results you are seeing of .25" - .3" are outstanding without a pointing model or optimized guide tuning.  Even with those steps in place, I'm not sure you would see much better results as indicated by PHD2 simply because the seeing in Bortle 7/8 is going to be a stronger influence on the indicated results than the mount performance is (assuming everything is running/setup correctly).  Enjoy your mount!!!

If I'm lucky I've only got another year to go on the Mach2 waiting list...   ;-)


Roland Christen
 


Total RMS dependent on seeing (I have Bortle 4 skies)
Just want to point out that the Bortle number has zero to do with seeing. Don't confuse seeing with transparency or light pollution. For instance, you can have huge amount of light pollution and have perfect seeing.

Rolando


-----Original Message-----
From: Clayton Yendrey <cyendrey@...>
To: main@ap-gto.groups.io
Sent: Fri, Jan 21, 2022 10:15 am
Subject: Re: [ap-gto] Imaging tonight with Mach2 at 5 below zero

Your best bet on tuning recommendations will be to post your log files to the PHD2 support group - the zip tool is in PHD2 and the link to the support forum is on their website.  To put some perspective on this, your current guide performance as indicated in your post is excellent, so you're chasing a difference that may not be visible/provide any tangible improvements unless you have a very long focal length OTA (>2000mm).  Being a little OCD myself, I've gone down that rabbit hole a few times only to be given a reality check by PHD2 Support when they pointed out that I was seeing guide performance better than the capability of most the mounts in use by amateurs.
If there is an issue with your PHD2 setup, I'd guess that default tuning parameters are too aggressive for a premium mount like the Mach2.  I have a Software Bisque MyT and it does not do well with the default settings in PHD2, doing best with aggression dialed back 10 - 20 points or so from the default.  Have you run a solid base line on your mount with PHD2 (PHD2 support is going to ask/request that)?  With encoders you should not have DEC backlash compensation enabled in the guide algorithm.
Instructions are on their website but you'll want to make sure you have a good/excellent  polar alignment,
Calibrate, then Run Guide assistant (all at or at least within 10dg of DEC 0, starting just west of the Meridian to insure a flip isn't required during the process.
Run a short 2- 5 minute guide session (until the Polar Alignment error indication stabilizes)
Update PHD2 with the setting recommendations from Guide Assistant, then run Guide Assistant again.  PHD2 Support likes to see 20 minutes, give or take on the longer session.  I usually go for two worm cycles when I'm doing this part, but you want at least one IMO.  Update the PHD2 settings again with the 'tweaked' recommendations from Guide Assistant.  Guide Assistant may also make some recommendations concerning which guide algorithm to use on either the RA or DEC.  On my MyT, it prefers the Low Pass 2 for DEC, YMMV.
As a non-encoder mount I'm happy to say that my MyT routinely gets .25"-.5" Total RMS dependent on seeing (I have Bortle 4 skies).  The mount is on a pier mounting with an excellent PA, a large pointing model, and with the ProTrack correcting algorithm turned on that having the TPoint model enables.  The A-P mount is no different, the encoders are not a magic pointing wand - you have to have the foundation steps completed to get the performance that mount can provide.
In Bortle 7/8 skies, seeing is pretty much always going to influence your guiding since your guide scope ( or if you are configured with an OAG) are not seeing the same filtered view as the imaging camera but rather full spectrum.  I think the guide results you are seeing of .25" - .3" are outstanding without a pointing model or optimized guide tuning.  Even with those steps in place, I'm not sure you would see much better results as indicated by PHD2 simply because the seeing in Bortle 7/8 is going to be a stronger influence on the indicated results than the mount performance is (assuming everything is running/setup correctly).  Enjoy your mount!!!
If I'm lucky I've only got another year to go on the Mach2 waiting list...   ;-)

--
Roland Christen
Astro-Physics


 

Hi Aaron

0.1" rms is an astonishingly low number, I don't know if you should be judging your results based on that.

0.25-0.3" is already excellent results. At this level of precision i think the RMS results are more about mount performance and less about guiding. For encoder mounts it's more about seeing conditions and encoders/modeling, with the guiding very gently keeping things on track

I would try building an all sky model in APCC Pro, which is probably the next most significant improvement beyond the encoders. 

Regarding guiding, you need to upload a guidelog to really know what is going on. Clayton mentioned the baseline guiding steps, which you can download here: 
https://www.dropbox.com/s/zrf0au7jaisvt85/How%20to%20create%20a%20baseline%20for%20guiding%20results%20using%20OpenPHD2.pdf?dl=0

When you use the New Profile Wizard, it will recommend using lowpass2 for your Dec algorithm. 

OpenPHD is doing a beta on some new features for encoder mounts, if you're interested in trying this drop me a private message and we can get you set up


Brian


ernie.mastroianni@...
 

I had no problems at all with my Mach2 at about 0 deg F in MKE earlier this month. Taken with a C925 at f/10.


Marcelo Figueroa
 

On Fri, Jan 21, 2022 at 12:14 AM, AaronW wrote:
I am a new owner of a Mach2 and am extremely happy with it (my first ever mount, actually!).  However, I never get anything close to 0.15 arc sec rms.  I have not yet attempted to build a pointing model and am simply guiding with PHD2.  But perhaps my PHD settings are not what they should be.  
 
I am imaging exclusively in narrowband in Bortle 7/8 skies, and seeing conditions vary from night to night, but even under “above average” seeing conditions (as defined by the app “Astrospheric”), the best I can get is 0.3 arc sec total rms (think I was at 0.25 for a few hours one night).  
 
I always image at a focal length of between 730 - 910mm, I polar align easily with SharpCap and am always within just a few arc seconds of error), and my PHD2 settings are as follows:

I also have a Mach 2 and also do pretty much only narrowband because of my light pollution. My recommendation is to build a model and forget the guiding, it is so nice not to hear anymore that annoying PHD2 beep when you lose the guide star.
 
You are going to have to experiment a bit with how long you can expose and keep the stars round and the light pollution doesn't start to become annoying. That depends on your particular setup.
 
 
 
 
 
 
 


 

>>>  it is so nice not to hear anymore that annoying PHD2 beep when you lose the guide star.

not that it fixes guiding problems, but you can disable the beeps in PHD :)

image.png


On Fri, Jan 21, 2022 at 10:37 AM Marcelo Figueroa via groups.io <marfig1970=yahoo.com@groups.io> wrote:
On Fri, Jan 21, 2022 at 12:14 AM, AaronW wrote:
I am a new owner of a Mach2 and am extremely happy with it (my first ever mount, actually!).  However, I never get anything close to 0.15 arc sec rms.  I have not yet attempted to build a pointing model and am simply guiding with PHD2.  But perhaps my PHD settings are not what they should be.  
 
I am imaging exclusively in narrowband in Bortle 7/8 skies, and seeing conditions vary from night to night, but even under “above average” seeing conditions (as defined by the app “Astrospheric”), the best I can get is 0.3 arc sec total rms (think I was at 0.25 for a few hours one night).  
 
I always image at a focal length of between 730 - 910mm, I polar align easily with SharpCap and am always within just a few arc seconds of error), and my PHD2 settings are as follows:

I also have a Mach 2 and also do pretty much only narrowband because of my light pollution. My recommendation is to build a model and forget the guiding, it is so nice not to hear anymore that annoying PHD2 beep when you lose the guide star.
 
You are going to have to experiment a bit with how long you can expose and keep the stars round and the light pollution doesn't start to become annoying. That depends on your particular setup.
 
 
 
 
 
 
 



--
Brian 



Brian Valente


Brent Boshart
 

I'm pleased with my Mach2 and PHD2 guiding with total RMS ranging from 0.25 to 0.4 depending on seeing.  However, I have noticed that the Dec RMS is usually 50% to 60% higher than RA RMS.  (My polar alignment with a permanent pier is within 1 arcminute.)  I have played around with PHD2 settings, but consistently Dec seems to give a higher RMS than RA.


Roland Christen
 

For encoder mounts the ideal thing is to not send any guide pulses if the star is lost. Maxim DL starts looking for the star and sends correction pulses, so in the end when the star returns, the axes have moved so far away that the star is outside the guide box. This is even more annoying than a beep.

Rolando

-----Original Message-----
From: Brian Valente <bvalente@...>
To: main@ap-gto.groups.io
Sent: Fri, Jan 21, 2022 12:45 pm
Subject: Re: [ap-gto] Imaging tonight with Mach2 at 5 below zero

>>>  it is so nice not to hear anymore that annoying PHD2 beep when you lose the guide star.

not that it fixes guiding problems, but you can disable the beeps in PHD :)

image.png

On Fri, Jan 21, 2022 at 10:37 AM Marcelo Figueroa via groups.io <marfig1970=yahoo.com@groups.io> wrote:
On Fri, Jan 21, 2022 at 12:14 AM, AaronW wrote:
I am a new owner of a Mach2 and am extremely happy with it (my first ever mount, actually!).  However, I never get anything close to 0.15 arc sec rms.  I have not yet attempted to build a pointing model and am simply guiding with PHD2.  But perhaps my PHD settings are not what they should be.  
 
I am imaging exclusively in narrowband in Bortle 7/8 skies, and seeing conditions vary from night to night, but even under “above average” seeing conditions (as defined by the app “Astrospheric”), the best I can get is 0.3 arc sec total rms (think I was at 0.25 for a few hours one night).  
 
I always image at a focal length of between 730 - 910mm, I polar align easily with SharpCap and am always within just a few arc seconds of error), and my PHD2 settings are as follows:

I also have a Mach 2 and also do pretty much only narrowband because of my light pollution. My recommendation is to build a model and forget the guiding, it is so nice not to hear anymore that annoying PHD2 beep when you lose the guide star.
 
You are going to have to experiment a bit with how long you can expose and keep the stars round and the light pollution doesn't start to become annoying. That depends on your particular setup.
 
 
 
 
 
 
 


--
Brian 



Brian Valente

--
Roland Christen
Astro-Physics


Roland Christen
 

Balance in Dec is important. Try to get it dead nuts balanced.

Roland

-----Original Message-----
From: Brent Boshart <bboshart@...>
To: main@ap-gto.groups.io
Sent: Fri, Jan 21, 2022 2:11 pm
Subject: Re: [ap-gto] Imaging tonight with Mach2 at 5 below zero

I'm pleased with my Mach2 and PHD2 guiding with total RMS ranging from 0.25 to 0.4 depending on seeing.  However, I have noticed that the Dec RMS is usually 50% to 60% higher than RA RMS.  (My polar alignment with a permanent pier is within 1 arcminute.)  I have played around with PHD2 settings, but consistently Dec seems to give a higher RMS than RA.

--
Roland Christen
Astro-Physics


Shailesh Trivedi
 

Roland,

I have experienced such a star is lost issue with my Mach2 and 1100 with AE. So my question is, if a plate-solve helps center the object and the polar alignment is within a few arc seconds of Alt  and AZ as reported by PEMPRO, do I even bother with guiding?

I thought the answer was dependent on the focal length and image scale.

Shailesh


Roland Christen
 

Sometimes I guide, sometimes I don't. Depends what I'm after. If you have a good model, then guiding may not be needed.

Rolando

-----Original Message-----
From: Shailesh Trivedi <shailesh.trivedi@...>
To: main@ap-gto.groups.io
Sent: Fri, Jan 21, 2022 5:01 pm
Subject: Re: [ap-gto] Imaging tonight with Mach2 at 5 below zero

Roland,

I have experienced such a star is lost issue with my Mach2 and 1100 with AE. So my question is, if a plate-solve helps center the object and the polar alignment is within a few arc seconds of Alt  and AZ as reported by PEMPRO, do I even bother with guiding?

I thought the answer was dependent on the focal length and image scale.

Shailesh

--
Roland Christen
Astro-Physics


Christopher M
 

-5F to -15F.  May I ask if this is the low temp encoder version or the standard encoder version?


Roland Christen
 

I have the standard temps on mine. Have not seen a problem, but they are not rated for -25F. and I haven't seen that low a temp in the last 10 years here.

Rolando



-----Original Message-----
From: Christopher M <mirfak@...>
To: main@ap-gto.groups.io
Sent: Fri, Jan 21, 2022 6:31 pm
Subject: Re: [ap-gto] Imaging tonight with Mach2 at 5 below zero

-5F to -15F.  May I ask if this is the low temp encoder version or the standard encoder version?

--
Roland Christen
Astro-Physics


Roland Christen
 

Howdy some more,

I'm imaging again tonight using the same guide scope and a different camera. The steadiness of the atmosphere is even better tonight. The stars in an eyepiece of my visual scope at 300x are not moving at all, just little round dots. The mount is again guiding smooth as silk, temperature is now a balmy 11 degrees F. Take a look at my guider graph, notice how responsive the Dec axis is to a small 0.3 arc sec error - one guide correction and it's back to the zero line. Lots of time where no corrections are happening. Guiding scope has 1600mm focal length, guider has 0.74 micron pixels at 0.95 arc sec per pixel.

Rolando




-----Original Message-----
From: Roland Christen via groups.io <chris1011@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Fri, Jan 21, 2022 6:45 pm
Subject: Re: [ap-gto] Imaging tonight with Mach2 at 5 below zero

I have the standard temps on mine. Have not seen a problem, but they are not rated for -25F. and I haven't seen that low a temp in the last 10 years here.

Rolando



-----Original Message-----
From: Christopher M <mirfak@...>
To: main@ap-gto.groups.io
Sent: Fri, Jan 21, 2022 6:31 pm
Subject: Re: [ap-gto] Imaging tonight with Mach2 at 5 below zero

-5F to -15F.  May I ask if this is the low temp encoder version or the standard encoder version?

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics


AaronW
 

Thanks all for the insightful comments.  I may perform some of the suggested tests, but I am reasonably certain that my local seeing conditions are the limiting factor here in Santa Monica.  I will report back if I learn otherwise.  

Thanks again for all your insight!

Best,
Aaron

On Jan 21, 2022, at 5:22 PM, Roland Christen via groups.io <chris1011@...> wrote:


Howdy some more,

I'm imaging again tonight using the same guide scope and a different camera. The steadiness of the atmosphere is even better tonight. The stars in an eyepiece of my visual scope at 300x are not moving at all, just little round dots. The mount is again guiding smooth as silk, temperature is now a balmy 11 degrees F. Take a look at my guider graph, notice how responsive the Dec axis is to a small 0.3 arc sec error - one guide correction and it's back to the zero line. Lots of time where no corrections are happening. Guiding scope has 1600mm focal length, guider has 0.74 micron pixels at 0.95 arc sec per pixel.

Rolando




-----Original Message-----
From: Roland Christen via groups.io <chris1011@...>
To: main@ap-gto.groups.io <main@ap-gto.groups.io>
Sent: Fri, Jan 21, 2022 6:45 pm
Subject: Re: [ap-gto] Imaging tonight with Mach2 at 5 below zero

I have the standard temps on mine. Have not seen a problem, but they are not rated for -25F. and I haven't seen that low a temp in the last 10 years here.

Rolando



-----Original Message-----
From: Christopher M <mirfak@...>
To: main@ap-gto.groups.io
Sent: Fri, Jan 21, 2022 6:31 pm
Subject: Re: [ap-gto] Imaging tonight with Mach2 at 5 below zero

-5F to -15F.  May I ask if this is the low temp encoder version or the standard encoder version?

--
Roland Christen
Astro-Physics

--
Roland Christen
Astro-Physics