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Best guide speed for Mach1GTO

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#1 John Miele

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Posted 22 May 2019 - 07:38 AM

Hi,

Coming from the ioptron world, I typically guided at 0.5x. in my Mach1 manual, I read that AP recommends guiding at 1.0x. Was wondering what speed the Mach1 users were finding to work best in the field. Thanks!... John

#2 rgsalinger

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Posted 22 May 2019 - 09:08 AM

I used 1.0x on my Mach 1 and I was happy with the results. Frankly, I have from time to time experimented with different guide rates on all of my mounts and found that unless set really low - like .1 - there did not seem to be an obvious sweet spot. So, I just go with what the guys who built it recommend.

Rgrds-Ross


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#3 StephenW

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Posted 22 May 2019 - 10:22 AM

Yeah, in the case of PHD2, it is already measuring your actual guide speed as part of calibration and then taking that into account when calculating & issuing corrective guide pulses.   

 

I think it only becomes an issue if you set a really low guide rate and then the necessary corrective guide pulse could hit the max guide pulse limits - in that scenario you may never be able to "catch up" with drift or other issues.

 

Not sure how other guide programs work.



#4 epdreher

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Posted 22 May 2019 - 11:10 AM

As was stated by others, 1.0x.  I also tried 0.7-9x with results maybe slightly worse, but seeing that evening could've been the cause.

 

Roland knows of what he speaks.



#5 John Miele

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Posted 22 May 2019 - 12:48 PM

Thanks guys!

 

I will stick with 1.0X for this mount...John



#6 Christopher Erickson

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Posted 22 May 2019 - 01:36 PM

Make sure to use the Lowpass 2 setting with PHD2 and AP mounts.



#7 epdreher

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Posted 22 May 2019 - 01:59 PM

I’d just read about that, Christopher. I’ve been using Auto but am looking forward to trying LP2.

What is the technical reason for that?

#8 Christopher Erickson

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Posted 22 May 2019 - 02:44 PM

AP mounts are significantly tighter and more rigid than most mounts and the default settings are more for the more common mounts out there. 


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#9 Peter in Reno

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Posted 22 May 2019 - 03:01 PM

Rolando has been testing and evaluating PHD2 extensively with A-P mounts and these are his recommended settings:

 

Guide rate at 1x

RA guiding algorithm: Hystersis at 0 and aggressiveness at 70%

Dec guiding algorithm: Lowpass2 and aggressiveness at 70%

 

You can find more information at ap-gto Yahoo Groups. His latest test with PHD2 was using with the new Mach2 with absolute encoders. Since Mach1 does not have absolute encoders, Rolando's PHD2 settings should be a very good start. You might have to slightly increase hystersis a little bit for RA axis.

 

PHD2 documentation: https://openphdguidi..._algorithms.htm

Peter 


Edited by Peter in Reno, 22 May 2019 - 03:04 PM.

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#10 StephenW

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Posted 22 May 2019 - 03:12 PM

Yeah, I think we should be a bit careful applying the results of the recent testing on the Mach2 + encoders to AP mounts that do not have encoders.

 

Mounts with encoders are pretty much "guaranteed" to move the exact amount you request them too, so there should be no need to factor in hysteresis from previous corrections when calculating the next correction.  This doesn't apply to mounts without encoders.

 

That said, if/when I ever get decent skies again(!), I'll also be testing Lowpass2 for DEC on my non-encoder Mach1, just to see how it performs.


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#11 Peter in Reno

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Posted 22 May 2019 - 03:18 PM

Mach1 is a very well behaved mount so I would think Rolando's PHD2 settings should work better than PHD2 default settings. 

 

Peter


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#12 leemr

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Posted 23 May 2019 - 05:01 AM

Mach1 is a very well behaved mount so I would think Rolando's PHD2 settings should work better than PHD2 default settings. 

 

Peter

 

Maybe...  not to discredit Roland, he clearly knows his mounts, but from posts on the AP-GTO forum it's clear to me that he's pretty new to PHD2. Mach 1's aren't perfect either and I certainly wouldn't expect a Mach 1 to behave as well as a mount with high end absolute encoders. In fact, my Mach 1 (late model with spring-loaded worms) only seems to behave somewhat in Dec if I enable backlash compensation in PHD2, which I recall Astro-Physics advising against.


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#13 Peter in Reno

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Posted 23 May 2019 - 11:54 AM

My point is Rolando's PHD2 settings is good and better than PHD2 default settings for A-P mounts, with or without AE. The settings are simply good starting points. That's all.

 

I give Rolando lots of credits for testing and evaluating PHD2 because PHD2 is a very popular auto guiding software so he can help others diagnosing his customers' mounts. 

 

Peter 


Edited by Peter in Reno, 23 May 2019 - 12:09 PM.

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