Mach 1 and tracking/guiding

[Rodd]

Any Mach 1 users out there?  I am trying to decide if I should get APCC pro so I can track/guide using both RA and DEC axis.  I have no complaints currently, but I would like to optimize accuracy.  Will I see a huge improvement using dual tracking/guiding?  The cost of the software is about $500.  I am not sure its worth it for me, as I have no use for the other elements of the software.  Currently at a focal length of 2800mm and can image unguided for 30 sec without impacting star shape.  The mount tracks with a single axis.  If I use APPCC pro and dual axis tracking, will I be able to extend the subs to 60 sec?  My guiding is pretty good--though I have not guided with an OAG at 2800mm.  I guide at 1,000mm and less using a guide scope and guiding seems pretty good.  But if I get dual axis guiding, will I see a big improvement?

 

Thanks,

Rodd

[markse68]

forgive my ignorance but can’t you use the free ascom driver for your mount (or isn’t there one?) and PHD2?

Mark

[rrb24]

Rodd

I've used APCC for over 6 years now and APCC-Pro for over a year.  If your plan is to do unguided imaging, you definitely will benefit from creating and using tracking models in the Pro version.   I have done up to 10 minute subs unguided at 1300mm FL with about 90% pass rate of my 0.4 limit of eccentricity.  I typically guide though even when using tracking models.  My guidescope is the Baader Vario finder and my guiding scale is 3"/px. 

APCC (and Pro) also allow you to set horizon and meridian limits for your mount which are very useful to prevent pier collisions and/or since you are not guiding, your scope tracking into an object.

Good luck,

Roberto

[Rodd]

20 minutes ago, markse68 said:

forgive my ignorance but can’t you use the free ascom driver for your mount (or isn’t there one?) and PHD2?

Mark

Yes, but I am inquiring about dual axis tracking/guiding.  I can guide now, but it’s single axis 

[markse68]

1 minute ago, Rodd said:

Yes, but I am inquiring about dual axis tracking/guiding.  I can guide now, but it’s single axis 

me being ignorant again sorry but on my mount phd2 guides in ra and dec

Mark

[Rodd]

10 minutes ago, rrb24 said:

Rodd

I've used APCC for over 6 years now and APCC-Pro for over a year.  If your plan is to do unguided imaging, you definitely will benefit from creating and using tracking models in the Pro version.   I have done up to 10 minute subs unguided at 1300mm FL with about 90% pass rate of my 0.4 limit of eccentricity.  I typically guide though even when using tracking models.  My guidescope is the Baader Vario finder and my guiding scale is 3"/px. 

APCC (and Pro) also allow you to set horizon and meridian limits for your mount which are very useful to prevent pier collisions and/or since you are not guiding, your scope tracking into an object.

Good luck,

Roberto

Thanks.  I won’t be able to model. Not enough clear sky time to justify losing some to trying to figure out how to do it.   When I shoot unguided I am using short subs, like 30 sec, so my only real issue is drift.  Correcting for drift every 30 min is a pain.  I am asking if dual axis tracking will improve tracking   When I guide I also use the vario guider at shorter focal lengths.  Not at 2800 mm though.  I’ll use an oag if I ever find time to install it   

[Rodd]

2 minutes ago, markse68 said:

me being ignorant again sorry but on my mount phd2 guides in ra and dec

Mark

How about tracking?  At present I am not guiding.  When I do guide, Will phd guide in two axis for all mounts?  Is dual axis guiding measurably better?

[david_taurus83]

I'm confused as well. PHD will issue guide pulses in both axis simultaneously with Skywatcher mounts, iOptron mounts etc

Surely your Mach 1 can do as well??

[Rodd]

1 hour ago, david_taurus83 said:

I'm confused as well. PHD will issue guide pulses in both axis simultaneously with Skywatcher mounts, iOptron mounts etc

Surely your Mach 1 can do as well??

Yes but I image with Maxim DL.  How would I coordinate dithering in phd2 with maxim?  But the real question is, is dual axis guiding necessary.  I take 30 sec unguided exposures at 2800mm and teh stars are round.  So my PA must be at least good enough for 30 sec exposures.  My typical guide exposure is 4 sec.  Will dual axis guiding really give me measurably better results?  I am thinking it will allow me to extend my unguided exposures becuase APCC pro also has dual axis tracking--which PHD2 does not (I don't think).  When I am guiding, will I see much of a difference?  

[Rodd]

A quick note...I don't see a reason for  self deprecation (calling themselves ignorant) or being confused....If the intent is to politely question my ignorance and confusion, I will spare you the trouble.  I am ignorant and am perpetually confused.  ....I am not contending anything....I am simply asking questions for which I do not know the answers.   

[markse68]

25 minutes ago, Rodd said:

A quick note...I don't see a reason for  self deprecation (calling themselves ignorant) or being confused....If the intent is to politely question my ignorance and confusion, I will spare you the trouble.  I am ignorant and am perpetually confused.  ....I am not contending anything....I am simply asking questions for which I do not know the answers.   

not deprecation Rodd but statement of fact as I don’t own a mount like yours and have no idea how it’s configured to work.

You say APCC can track in both axes but isn’t tracking usually just in RA with accurate polar alignment taking care of Dec? How does it know how to track in Dec without guiding feedback? Or is this for other objects that don’t move in Sidereal? 

Someone who knows Maxim Dl would have to comment on your dithering question.

Mark

[Stu]

31 minutes ago, Rodd said:

A quick note...I don't see a reason for  self deprecation (calling themselves ignorant) or being confused....If the intent is to politely question my ignorance and confusion, I will spare you the trouble.  I am ignorant and am perpetually confused.  ....I am not contending anything....I am simply asking questions for which I do not know the answers.   

Rodd, from what I have read, I think everyone is just trying to understand your problem and help. Stick with it and I’m sure you’ll get the help you need. Not from me though!! 🤪🤣

[Rodd]

11 minutes ago, markse68 said:

not deprecation Rodd but statement of fact as I don’t own a mount like yours and have no idea how it’s configured to work.

You say APCC can track in both axes but isn’t tracking usually just in RA with accurate polar alignment taking care of Dec? How does it know how to track in Dec without guiding feedback? Or is this for other objects that don’t move in Sidereal? 

Someone who knows Maxim Dl would have to comment on your dithering question.

Mark

I don't know...George at Astrophysics said that APCC can track and guide in 2 axis.  that's the extent of my knowledge.  Maybe it is not correct and what you say is true--which would mean it would have no impact on my tracking.  So my real question that I am trying to answer is ...Is dual axis guiding really measurably better with a high end mount.  Normally I use 4 sec guide exposures.  If tracking accounts for movement in DEC, then it seems to me that if I can take 30 sec unguided exposures at 2800 mm and have round stars with FWHM about at seeing (I can't imagine seeing at my location is often better than 1.5 arcsec, which, on a good night, I am able to achieve) that corrections in DEC over 4 sec would amount to a measurable benefit (but I really don't know ).  The reason I ask is I am planning to start gyuiding again (I am tired of the correct for drift every 30 min approach--as well as processing thousands of subs).  So, now is teh time to decide about changing my guiding.

[Rodd]

25 minutes ago, markse68 said:

not deprecation Rodd but statement of fact as I don’t own a mount like yours and have no idea how it’s configured to work.

You say APCC can track in both axes but isn’t tracking usually just in RA with accurate polar alignment taking care of Dec? How does it know how to track in Dec without guiding feedback? Or is this for other objects that don’t move in Sidereal? 

Someone who knows Maxim Dl would have to comment on your dithering question.

Mark

Here is what George at AP said.  He differentiates tracking and guiding, so I don't think he meant guiding.....that's possible though.  Maybe he means with modeling APCC will allow for better tracking.

 

"...Guiding and tracking depend on many factors.    APCC Pro can assist you with better tracking (dual axis).

Edited September 15, 2021 by Rodd

[rrb24]

Rodd

I think you are confused between guiding out errors  in general and correcting tracking using a model.

If you use a guider, you correct both RA and DEC errors in the tracking of your mount by brute force.  Your guider doesn't know if your mount is misaligned.  When it sends a signal to move the scope it is simply reacting to a movement in the image of the star in your guide camera.  Whether that movement is caused by the atmosphere, poor polar alignment, atmospheric refraction, the guider doesn't know.    From your posts it appears you experience significant drift.  Start by addressing this.  It will make any guiding easier.  If not, you will end up with field rotation in your images  - even if they are short - across the night when you come to stack them.  Use SharpCap; it takes 5 minutes to achieve almost perfect polar alignment with it which will translate in imperceptible drift.

Separately, APCC-Pro will create two models if you were to use its APPM utility:  a pointing and a tracking model.  The pointing model will correct for polar alignment, orthogonality and other mechanical errors.  It will improve your pointing only.  The tracking model will allow you to issue corrections to the speed of your motors depending on what position you are on the sky.   The speed at which objects move across the sky is not uniform.  It varies by declination and is also influenced by atmospheric phenomena including temperature.  APPC-Pro will allow to track at differential rates depending on those parameters allowing you to image unguided for longer.  Or to guide only seeing induced errors - reducing the work PHD2 has to do - and translating in tighter stars.

If you are going to stick to short exposures and cannot fully address your drift issues, don't buy the software.  

Roberto

[Rodd]

5 minutes ago, rrb24 said:

Rodd

I think you are confused between guiding out errors  in general and correcting tracking using a model.

If you use a guider, you correct both RA and DEC errors in the tracking of your mount by brute force.  Your guider doesn't know if your mount is misaligned.  When it sends a signal to move the scope it is simply reacting to a movement in the image of the star in your guide camera.  Whether that movement is caused by the atmosphere, poor polar alignment, atmospheric refraction, the guider doesn't know.    From your posts it appears you experience significant drift.  Start by addressing this.  It will make any guiding easier.  If not, you will end up with field rotation in your images  - even if they are short - across the night when you come to stack them.  Use SharpCap; it takes 5 minutes to achieve almost perfect polar alignment with it which will translate in imperceptible drift.

Separately, APCC-Pro will create two models if you were to use its APPM utility:  a pointing and a tracking model.  The pointing model will correct for polar alignment, orthogonality and other mechanical errors.  It will improve your pointing only.  The tracking model will allow you to issue corrections to the speed of your motors depending on what position you are on the sky.   The speed at which objects move across the sky is not uniform.  It varies by declination and is also influenced by atmospheric phenomena including temperature.  APPC-Pro will allow to track at differential rates depending on those parameters allowing you to image unguided for longer.  Or to guide only seeing induced errors - reducing the work PHD2 has to do - and translating in tighter stars.

If you are going to stick to short exposures and cannot fully address your drift issues, don't buy the software.  

Roberto

Thanks Roberto--yes, I was confused.  I am glad to learn guiding is dual axis.  Regarding drift--it is not really significant--but for a small sensor at 2800 mm, it is annoying.   I have sharpcap--though maybe not the version required to do polar alignment?  Is that free?  Even if costs money--say less than $50 it might be worth it.  The AP RAPAS gets me pretty close.  I can routinely take 30 min exposures when I am shooting narrowband and guiding.  I am more interested in eliminating drift so I can image without guiding for longer.  If I can image for 120 sec, that should cover most broadband targets nicely with a CMOS camera.  And I plan to use the .7x reducer, so my focal length will be 1,960 with a wider FOV and faster SNR.  I could do a drift alignment, but it will eat up imaging time and I am a bit scared of trying it.  Does Sharpcap really take 5 min? is it easy?  is it more accurate than the RAPAS?  

The other question is, would APCC pro allow me to image for 10-20 min unguided if I use the tracking model?  At some point I will install the OAG (a bit scare of that too, but I have a nice one).  So I do plan on guiding again.  Do you think APCC pro with its models would improve my guiding more than perfect polar alignment and guiding like I always do?  

[Rodd]

26 minutes ago, rrb24 said:

Use SharpCap; it takes 5 minutes to achieve almost perfect polar alignment with it which will translate in imperceptible drift.

I looked into it--it won't work with the C11Edge--I would have to change scopes (I do not have a guide scope on the C11).  Changing scopes is a big deal for me at the moment.  My FSQ 106 is being serviced.  My TOA 130 is boxed up ready to be sent for cleaning and TLC.  Even if I used a camera like the ASI 174, which is the widest FOV planetary camera I have, the FOV would still be too restrictive.  

When I switch back to a refractor, which I guide using a guidescope, sharpcap seems like it would be  excellent.  Then again, at 318mm-70mm my PA has always been good enough.  I measure my success in terms of FWHM.  Seeing for me is usually between 2 and 3.  On a good nigh with my C11 Edge unguided for 30 sec I achieve 1.4-1.8 FWHM--I figure my seeing can't be better than that.  So more accuracy wont help as it will be blurred by seeing.  If I was imaging in Chile, or DSW, or some such place, where the seeing is .3 arcsec, then I am sure more accuracy would really help.

Its hard to know where I should place my efforts--other than acquisition, which I rarely get to do.  Come a clear night, will I be willing to spend time fiddling with this stuff with a week of clouds confronting me the next day.....it tough.

[rrb24]

There’s a paid version of SharpCap that will allow you to use its advanced tools. Go to their website and check. It costs very little and their polar alignment tool is very reliable. 
Your RAPAS is only as accurate as your first polar alignment. It doesn’t come polar aligned for all mounts. You first have to drift align to set it (or use SharpCap) and then it will give you very good polar alignment visually if your move/reassemble your setup. If your setup is permanent, you don’t really need it. 
APCC-Pro will allow you to go unguided for longer - if you use the tracking model. I don’t know if as long as 20 minutes for a >1000mm FL scope but as I’ve said I’ve done 10 minute images at 1300mm repeatedly. 

Roberto

[rrb24]

5 minutes ago, Rodd said:

it won't work with the C11Edge

If you have a guidescope you can use it to polar align with SharpCap. But yes, a compound telescope with a mirror is not recommended as SharpCap will ask you to rotate your RA by ~6hrs and the mirror may shift. 
 

Roberto

[Rodd]

5 minutes ago, rrb24 said:

There’s a paid version of SharpCap that will allow you to use its advanced tools. Go to their website and check. It costs very little and their polar alignment tool is very reliable. 
Your RAPAS is only as accurate as your first polar alignment. It doesn’t come polar aligned for all mounts. You first have to drift align to set it (or use SharpCap) and then it will give you very good polar alignment visually if your move/reassemble your setup. If your setup is permanent, you don’t really need it. 
APCC-Pro will allow you to go unguided for longer - if you use the tracking model. I don’t know if as long as 20 minutes for a >1000mm FL scope but as I’ve said I’ve done 10 minute images at 1300mm repeatedly. 

Roberto

The RAPAS uses a reticle that has a pattern that you match to a software image on eth computer.  Based on your location, the software shows you where to position polaris.  You put it there.  It works for all scopes that the scope can be installed on.  I will polar align and not image for 3 weeks and Polaris will be exactly wghere it was the last time I looked--it has to be close.  If it was off, it would migrate a bit out of the circle.  I check PA every time I image.  As I said--30 min subs are fine at 1,000 mm.  I attached an image i did of the bubble using 30 min subs at 1,000 mm.  I can't see PA being off significantly, unless (and this I might suspect) that PA is not as important as some think when one is guiding.  But I could be wrong about that.

[Rodd]

7 minutes ago, rrb24 said:

If you have a guidescope you can use it to polar align with SharpCap. But yes, a compound telescope with a mirror is not recommended as SharpCap will ask you to rotate your RA by ~6hrs and the mirror may shift. 
 

Roberto

I can lock the mirror.  But--I could also install the Bario Vario guide scope --even though the connection may not be as stable as I would like for guiding, it would be stable enough to do a PA right?  I think I read where you don't have to worry about the guidescope and main scope being perfectly aligned.  I think I can install the TAK shoe that holds the Vario Guider into the screw holes where a finder bracket attached on the C11 Edge just for this purpose

[rrb24]

14 hours ago, Rodd said:

The RAPAS uses a reticle that has a pattern that you match to a software image on eth computer.  Based on your location, the software shows you where to position polaris.  You put it there.  It works for all scopes that the scope can be installed on.  I will polar align and not image for 3 weeks and Polaris will be exactly wghere it was the last time I looked--it has to be close.  If it was off, it would migrate a bit out of the circle.  I check PA every time I image.  As I said--30 min subs are fine at 1,000 mm.  I attached an image i did of the bubble using 30 min subs at 1,000 mm.  I can't see PA being off significantly, unless (and this I might suspect) that PA is not as important as some think when one is guiding.  But I could be wrong about that.

Yes, I have a RAPAS and it’s great. What I’m saying is that it’s only as good as its reticle is aligned to your mount and the polar axis. It was made separately from your mount. If your mount is misaligned and the rapas is not completely aligned to the mount’s misaligned axis it will not be able to fully correct your error. That’s why you want to get the three in line first time you use it: Pole, mount and RAPAS. That way next time you use it, it will tell you how far off the pole you are - because it’s perfectly aligned with your mount. 

Edited September 16, 2021 by rrb24

[Rodd]

On 15/09/2021 at 14:24, rrb24 said:

Yes, I have a RAPAS and it’s great. What I’m saying is that it’s only as good as its reticle is aligned to your mount and the polar axis. It was made separately from your mount. If your mount is misaligned and the rapas is not completely aligned to the mount’s misaligned axis it will not be able to fully correct your error. That’s why you want to get the three in line first time you use it: Pole, mount and RAPAS. That way next time you use it, it will tell you how far off the pole you are - because it’s perfectly aligned with your mount. 

I understand. It was installed when I bought the mount.  I know I am off a little. But honestly, if I can take 30 min subs, how bad can it be?  Not bad enough for me to spend time getting it perfect and lose imaging time. It has to be close.  Close enough for jazz as they say.  This weekend it will be clear but a full moon.  I want to install the reducer and oag and it will be a perfect opportunity to try a drift alignment.  The problem is my horizons are not all clear. But I might as well try it.  Once I get it perfect, I can adjust the RAPAS so it is perfectly aligned.

Edited September 17, 2021 by Rodd

[Rodd]

 

On 15/09/2021 at 13:19, rrb24 said:

If not, you will end up with field rotation in your images  - even if they are short - across the night when you come to stack them

I'm sorry--the image of the Bubble Nebula I posted was 300 sec subs--I had switched to the ASI 1600.  Here is an image using 1800 sec subs with the CCD STT-8300.  Still looks OK to me as far as rotation and star shape.  Focal length is only 700mm.  But now I use the asi 1600 exclusively, so 300 sec subs are the longest I use.

Edited September 17, 2021 by Rodd