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How well do you autoguide? (RMS error?)

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26 replies to this topic

#1 Michael Covington

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Posted 25 November 2016 - 12:33 AM

Let's take a poll.  How good is your autoguiding, and with what equipment?  If you use PHD2, tell me the overall RMS error in arc-seconds.

 

Here's one of mine: With either a CGEM or an AVX mount, and a telescope with a tiny 35x135mm guidescope piggybacked on it, and a DFM guide camera and PHD2, I get about 2" total rms error.  I tend to think I'm at the resolution limit of that tiny guidescope and at the next opportunity will switch to something bigger.  Also that the seeing is not too good where I'm set up.

 


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#2 jfrech14

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Posted 25 November 2016 - 12:52 AM

Autoguiding at 2800mm using an OAG and SX Lodestar in pretty bad skies I would get around .5" RMS with my CGEM DX. Autoguiding with a 50mm guide scope on my iOptron CEM25 I get around 1-2" RMS in good skies if I remember correctly. I miss guiding at the same pixel scale or less than my imaging camera but long focal lengths can be such pains. As long as my eccentricity is below .15 I am a happy camper whatever my guiding is haha.


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#3 Jerry Lodriguss

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Posted 25 November 2016 - 01:59 AM

Autoguiding with an AT65EDQ and 2x Barlow at 759mm of focal length Piggybacked on top of AP 130EDFGT

AP Mach1GTO mount

Lodestar X2 autoguider

PHD2

 

Good seeing (maybe 2") averages around 0.3 arcsconds RMS in the guiding

Average seeing (maybe 2-3") averages around 0.5 arcseconds RMS in the guiding.

Bad seeing (more than 3") averages around 1.0 arcseconds RMS in the guiding.

 

Jerry


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#4 rekokich

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Posted 25 November 2016 - 04:39 AM

Autoguiding with Orion 60mm f4, 240mm fl, and the Celestron AVX mount, near the zenith, median total RMS is 1.6", +/- 0.3". So far, never better than 1.3", and never worse than 1.9" during 300 second exposures. I was thinking of adding a 2x Barlow, but I am not sure the mount is capable of better accuracy.


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#5 bobzeq25

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Posted 25 November 2016 - 11:10 AM

In the usual (lousy) seeing in my backyard, about 1" rms total.

 

On a bad night for seeing, 1.2.

 

On a good night for seeing, 0.7.

 

I think there's a bit more to be squeezed out with better settings in PhD2.  At 3 seconds exposure and fairly low agressiveness, I think I'm _still_ chasing seeing.  CEM60, 66/400 guidescope, ASI120MM.

 

Maybe Metaguide?

 

My polar alignment is not perfect, the lousy seeing causes jitter in the final step with the PoleMaster.


Edited by bobzeq25, 25 November 2016 - 11:13 AM.

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#6 17.5Dob

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Posted 25 November 2016 - 03:22 PM

Seeing dependent, using an Orion 50mm/QHY5L-ii guidescope, PHD2-EQMOD,and my Orion Atlas,  I "average" around 0.75" RMS. On really good nights, that can drop towards 0.5" RMS, on really bad nights it can creep up towards ~ 1.0" RMS


Edited by 17.5Dob, 25 November 2016 - 03:25 PM.


#7 leveye

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Posted 25 November 2016 - 03:43 PM

I've had graphs like this on a few occasions.

 

 PHD2 graph (1 of 1).jpg


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#8 entilza

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Posted 25 November 2016 - 04:10 PM

I've had graphs like this on a few occasions.

 

 attachicon.gifPHD2 graph (1 of 1).jpg

 

This is not a good example unfortunately.

 

Your scale is up to 16"  you should reduce that to 8 or 4 depending on your system so you can actually see the curve.

 

Your history is set to 50, increase that to a 100 for more history

 

The total error is 1.69" That's higher than what the average user is reporting in this thread.  You can see the RA error is the issue.

 

Turn on corrections so you can see what corrections are being sent, this can help give you some 

 

Check out the PHD2 main website there is a link to a new recetnly posted document on "PHD2 Best practices"  http://openphdguiding.org/  It's actually good for everyone to review.


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#9 leveye

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Posted 25 November 2016 - 04:45 PM

 

I've had graphs like this on a few occasions.

 

 attachicon.gifPHD2 graph (1 of 1).jpg

 

This is not a good example unfortunately.

 

Your scale is up to 16"  you should reduce that to 8 or 4 depending on your system so you can actually see the curve.

 

Your history is set to 50, increase that to a 100 for more history

 

The total error is 1.69" That's higher than what the average user is reporting in this thread.  You can see the RA error is the issue.

 

Turn on corrections so you can see what corrections are being sent, this can help give you some 

 

Check out the PHD2 main website there is a link to a new recetnly posted document on "PHD2 Best practices"  http://openphdguiding.org/  It's actually good for everyone to review.

 

I was getting perfectly round stars at over 5 minutes. What can I say. It was working perfectly.



#10 Michael Covington

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Posted 25 November 2016 - 04:57 PM

 

 

I've had graphs like this on a few occasions.

 

 attachicon.gifPHD2 graph (1 of 1).jpg

 

This is not a good example unfortunately.

 

Your scale is up to 16"  you should reduce that to 8 or 4 depending on your system so you can actually see the curve.

 

Your history is set to 50, increase that to a 100 for more history

 

The total error is 1.69" That's higher than what the average user is reporting in this thread.  You can see the RA error is the issue.

 

Turn on corrections so you can see what corrections are being sent, this can help give you some 

 

Check out the PHD2 main website there is a link to a new recetnly posted document on "PHD2 Best practices"  http://openphdguiding.org/  It's actually good for everyone to review.

 

I was getting perfectly round stars at over 5 minutes. What can I say. It was working perfectly.

 

With what imaging setup?  1.69" might be good enough.



#11 17.5Dob

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Posted 25 November 2016 - 07:23 PM

I've had graphs like this on a few occasions.

 

 attachicon.gifPHD2 graph (1 of 1).jpg

At that scale my little unguided iOptron SkyTracker would look great, just saying. :lol: 

When your graph looks like that at 4" resolution instead of 16", then you have good tracking, or a hot pixel.

On a "Good Night" mine will look like THIS



#12 andysea

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Posted 26 November 2016 - 08:41 PM

This is with the Mach1, I believe I was using the 50mm Orion mini guide scope with the ZWO ASi224 - or it might have been the lodestar, I just can't remember. On good seeing nights, I get similar results with the AP900 and the OAG when I use my RC telescope. Sorry I don't have a larger screenshot, this is what I found in my computer. However it shows the RMS numbers.

On nights of average seeing I get around 0.5" to 0.7" RMS in RA and on nights of bad seeing it hovers around 1" and even 1.5".
 

Attached Thumbnails

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Edited by andysea, 26 November 2016 - 08:51 PM.

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#13 Ron in Michigan

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Posted 07 May 2018 - 08:53 AM

Im like andysea.  Mach1  80mm guide scope. Around  0.22  -  0.33     Lodestar X2
 

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Edited by Ron in Michigan, 07 May 2018 - 08:54 AM.


#14 Michael Covington

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Posted 07 May 2018 - 09:21 AM

When the RMS reading is less than 0.5" I start wondering whether it is correct -- does PHD2 have the correct focal length and pixel size for the guiding apparatus?

My rule of thumb is that 2" is poor, 1.5" is mediocre, 1.0" is good, and 0.5" is outstanding.

I got 0.1" one night and turned out to have some settings wrong.


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#15 leveye

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Posted 07 May 2018 - 09:46 AM

0.06 most nights thank the stars.


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#16 bobzeq25

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Posted 07 May 2018 - 10:02 AM

In 1-1/2 years, I've progressed from 0.7-1.2 to 0.5-0.9.  If it gets above that, it's generally a sign that seeing is so bad it's not worth imaging.  Maybe with the SV70T.



#17 Thundermoon1994

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Posted 07 May 2018 - 01:32 PM

For my Atlas EQ-G, using an Orion 50mm Mini guide scope and ASI224MC - Great nights: 0.5 - 0.7", Average: 0.6 - 0.9", Poor: 0.9 - 1.1".  Given that all my deep sky imaging has been with an 80mm APO at f/4.8, the guiding is plenty good enough, even on poor nights.  I recently acquired an ASI178MM-Cool, so that will test my guiding more.  I'm going from 2.3" per pixel currently to 1.3" per pixel.

 

For my (late) AVX, using the same guide scope and guide cam, I struggled to get that thing below 1.5".  It took constant babysitting.

 

Here's a shot of my best guiding so far with the Atlas:

image1(1).JPG

 

 

Damien


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#18 squreshi786

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Posted 07 May 2018 - 04:49 PM

Guys, almost feel ashamed putting this up but hope you can help. My guiding is playing up here in UK. I have a Losmandy G11. Use a 60mm altair astro guidescope with loadstar X2 and PHD2. For the last month or so have been having issues with some times guiding works while other its just a pain as you can see. Tonight was a hot night visibility was modest (I also have light pollution. But need help if you could diagnose and make some suggestions. My calibration is not bad, but look at a 5 min sub, whats wrong with the stars?

 

Thanks

 

Saqib

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#19 bobzeq25

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Posted 07 May 2018 - 05:07 PM

Guys, almost feel ashamed putting this up but hope you can help. My guiding is playing up here in UK. I have a Losmandy G11. Use a 60mm altair astro guidescope with loadstar X2 and PHD2. For the last month or so have been having issues with some times guiding works while other its just a pain as you can see. Tonight was a hot night visibility was modest (I also have light pollution. But need help if you could diagnose and make some suggestions. My calibration is not bad, but look at a 5 min sub, whats wrong with the stars?

 

Thanks

 

Saqib

Hard to read the tiny jpg, but spikes like that can be cable drags and snags.



#20 grsotnas

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Posted 07 May 2018 - 07:05 PM

I'm using ASI120MM + BST Starguider 50mm guidescope on a HEQ5 (stock, not belt modded). PHD2.

I usually get 1.3-1.6". Once got 0.8", sometimes up to 2".

It doesn't make that difference to me as my longest FL is 200mm, but I'm working towards inproving it eyeing my future telescope setup.

Edited by grsotnas, 07 May 2018 - 07:07 PM.


#21 Michael Covington

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Posted 07 May 2018 - 07:35 PM

In 1-1/2 years, I've progressed from 0.7-1.2 to 0.5-0.9.  If it gets above that, it's generally a sign that seeing is so bad it's not worth imaging.  Maybe with the SV70T.

That sounds right for good equipment and good technique.



#22 Michael Covington

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Posted 07 May 2018 - 07:37 PM

For my Atlas EQ-G, using an Orion 50mm Mini guide scope and ASI224MC - Great nights: 0.5 - 0.7", Average: 0.6 - 0.9", Poor: 0.9 - 1.1".  Given that all my deep sky imaging has been with an 80mm APO at f/4.8, the guiding is plenty good enough, even on poor nights.  I recently acquired an ASI178MM-Cool, so that will test my guiding more.  I'm going from 2.3" per pixel currently to 1.3" per pixel.

 

For my (late) AVX, using the same guide scope and guide cam, I struggled to get that thing below 1.5".  It took constant babysitting.

 

Yes, a lot depends on your mount and its condition.  Those results sound right.



#23 Michael Covington

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Posted 07 May 2018 - 07:39 PM

My guiding problem lately, I've just figured out, is "terra non firma." I've been setting up in my driveway, and the concrete seems to be breaking up beneath the surface.  That means shifts as big as 40" (width of Jupiter) when I step near the telescope, and occasional 1" to 2" jerks that are probably thermal contraction and settling of the concrete.

From now on I'm setting the mount up on the ground, not the driveway.
 


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#24 555aaa

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Posted 07 May 2018 - 07:39 PM

This thread is a duplicate (more or less) of the "your guiding graph - please share it here" thread.

 

https://www.cloudyni...ph#entry8473470


Edited by 555aaa, 07 May 2018 - 07:46 PM.


#25 shiver

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Posted 18 March 2020 - 01:26 PM

I get about 0.5-0.9 Total RMS error using my Meade LX85 with 8"SCT and  Focal reducer ( about 1305 mm focal length ).Using OAG with ASI290mm mini and ASIair for guiding. It usually moves back and forth from those numbers.  This took ALOT of time and dozens of tries to attain this. I imagine more PPEC training will improve it over time.

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Edited by shiver, 18 March 2020 - 01:29 PM.



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