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PHD2 the struggle

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#1 EEBA

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Posted 20 September 2020 - 05:49 AM

When I was feeling happy taking my baby steps learning how to use Pixinsight. I decided to improve my images quality by getting better guiding.
I was getting 0.8 to 1.3 total RMS using my ZWO asi 120 MC guide camera. Everything changed when a seasoned Astrophotographer in Cloudy nights told me I am not suppose to use 0.7 sec exposure in PHD2 . I said that yields the best number for me.
I followed directions and I tried to increase the exposure time. My numbers worsen, I thought, perhaps my camera is low quality to get good guiding. Nope, I upgraded to ZWO asi 290 mm. RESULTS worsen.
My equipment now is :
HeQ5 pro brand new [6 months with me].
WO zenithstar 73 , FL 430mm
Main image camera zwo 533 MC OSC.
WO 200 mm guidescope with nowZWO 290mm guide camera.
Polemaster.
Eqmode
APT
PhD2.

So far since my new guide camera I tried:

Level mount to the floor with big bar level(not the one in the mount).
Perfectly balance dec
Perfectly balanced RA.
Polemaster Polar alignment.
Calibrated near equator and meridian.
Move north before calibration.
Move south before calibration
Record the mount graph without guiding output to see mount behavior.
Guide auto
Guide north only
Guide south only.
Guide 1,2,3,4,5,6,10,15 seconds exposure in phd2.
Calibrated multiple times and different lengths.
Played with phd2 settings.
Played with eq mode RA and Dec speed in siderail..
My backlash in my dec is 3800ms.
Best guiding numbers trying everything mentioned above was 1.4 arc sec in RA 0.6 in Dec @ 0.5 sec phd2 exposure.
I noticed my red line in the graph ( declination) was almost always between 0.5 and 0.7 in exposures from 1 sec to 6 sec , it didn't vary much.
My blue line in the graph ( RA) most of the time was around 1.7 arc sec.

If the backlash is in the declination axis, why the RA is off?
My graph looks red line not to bad almost parallel to x axis, but the blue line is a constant wave up and down, up and down.
The total RMS is around 1.9 .
What is the next step at this point?
I am running out of ideas. Please help

#2 imtl

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Posted 20 September 2020 - 05:54 AM

You should post your log files



#3 EEBA

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Posted 20 September 2020 - 06:01 AM

https://photos.app.g...TtmG9Ryb4Ynoz27

 

This how my graph looks.



#4 EEBA

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Posted 20 September 2020 - 06:04 AM

I have what I have trying all night which is what I mentioned above. I can try to copy and paste here.  Let me try



#5 EEBA

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Posted 20 September 2020 - 06:10 AM

Guiding Begins at 2020-09-20 01:23:03
Equipment Profile = WO290
Dither = both axes, Dither scale = 1.000, Image noise reduction = none, Guide-frame time lapse = 0, Server enabled
Pixel scale = 2.99 arc-sec/px, Binning = 1, Focal length = 200 mm
Search region = 15 px, Star mass tolerance = 50.0%
Camera = ZWO ASI290MM Mini (ASCOM), full size = 1936 x 1096, have dark, dark dur = 1500, no defect map, pixel size = 2.9 um
Exposure = 1500 ms
Mount = EQMOD HEQ5/6 (ASCOM), connected, guiding enabled, xAngle = 83.3, xRate = 2.126, yAngle = -13.2, yRate = 2.656, parity = +/-
Norm rates RA = 7.0"/s @ dec 0, Dec = 7.9"/s; ortho.err. = 6.5 deg
X guide algorithm = Hysteresis, Hysteresis = 0.100, Aggression = 0.700, Minimum move = 0.200
Y guide algorithm = Resist Switch, Minimum move = 0.200 Aggression = 100% FastSwitch = enabled
Backlash comp = disabled, pulse = 2272 ms
Max RA duration = 2500, Max DEC duration = 2500, DEC guide mode = Auto
RA Guide Speed = 7.5 a-s/s, Dec Guide Speed = 7.5 a-s/s, Cal Dec = 5.5, Last Cal Issue = None, Timestamp = 9/20/2020 1:09:39 AM
RA = 3.78 hr, Dec = 24.1 deg, Hour angle = -3.28 hr, Pier side = West, Rotator pos = N/A, Alt = 46.3 deg, Az = 89.6 deg
Lock position = 535.738, 1013.600, Star position = 535.738, 1013.600, HFD = 2.79 px



#6 EEBA

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Posted 20 September 2020 - 06:15 AM

Calibration Begins at 2020-09-19 23:35:14
Equipment Profile = WO290
Dither = both axes, Dither scale = 1.000, Image noise reduction = none, Guide-frame time lapse = 0, Server enabled
Pixel scale = 2.99 arc-sec/px, Binning = 1, Focal length = 200 mm
Search region = 15 px, Star mass tolerance = 50.0%
Camera = ZWO ASI290MM Mini (ASCOM), full size = 1936 x 1096, have dark, dark dur = 2500, no defect map, pixel size = 2.9 um
Exposure = 2500 ms
Mount = EQMOD HEQ5/6 (ASCOM), Calibration Step = 850 ms, Calibration Distance = 25 px, Assume orthogonal axes = no
RA Guide Speed = 7.5 a-s/s, Dec Guide Speed = 7.5 a-s/s
RA = 23.06 hr, Dec = 0.4 deg, Hour angle = -0.36 hr, Pier side = West, Rotator pos = N/A, Alt = 56.0 deg, Az = 170.3 deg
Lock position = 1881.115, 665.319, Star position = 1880.717, 664.458, HFD = 3.42 px
West calibration complete. Angle = 82.7 deg, Rate = 2.570 px/sec, Parity = Even
North calibration complete. Angle = -9.5 deg, Rate = 2.442 px/sec, Parity = Odd

 

Guiding Begins at 2020-09-19 23:38:19
Equipment Profile = WO290
Dither = both axes, Dither scale = 1.000, Image noise reduction = none, Guide-frame time lapse = 0, Server enabled
Pixel scale = 2.99 arc-sec/px, Binning = 1, Focal length = 200 mm
Search region = 15 px, Star mass tolerance = 50.0%
Camera = ZWO ASI290MM Mini (ASCOM), full size = 1936 x 1096, have dark, dark dur = 2500, no defect map, pixel size = 2.9 um
Exposure = 2500 ms
Mount = EQMOD HEQ5/6 (ASCOM), connected, guiding enabled, xAngle = 82.7, xRate = 2.570, yAngle = -9.5, yRate = 2.442, parity = +/-
Norm rates RA = 7.7"/s @ dec 0, Dec = 7.3"/s; ortho.err. = 2.2 deg
X guide algorithm = Hysteresis, Hysteresis = 0.100, Aggression = 0.700, Minimum move = 0.200
Y guide algorithm = Resist Switch, Minimum move = 0.200 Aggression = 100% FastSwitch = enabled
Backlash comp = disabled, pulse = 2000 ms
Max RA duration = 2500, Max DEC duration = 2500, DEC guide mode = Auto
RA Guide Speed = 7.5 a-s/s, Dec Guide Speed = 7.5 a-s/s, Cal Dec = 0.4, Last Cal Issue = None, Timestamp = 9/19/2020 11:38:19 PM
RA = 23.06 hr, Dec = 0.4 deg, Hour angle = -0.31 hr, Pier side = West, Rotator pos = N/A, Alt = 56.1 deg, Az = 171.7 deg
Lock position = 1884.672, 667.318, Star position = 1884.672, 667.318, HFD = 3.59 px



#7 Boeglewatcher

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Posted 20 September 2020 - 06:33 AM

How do the stars look like in your pics? Round? Are you happy w the star shape or not?

#8 imtl

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Posted 20 September 2020 - 06:39 AM

You put 100% aggression for RA. You are over-correcting like crazy. Look at the saw-tooth shape of your RA. Lower it to 50-60 and increase your exposure time. 



#9 EEBA

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Posted 20 September 2020 - 06:41 AM

How do the stars look like in your pics? Round? Are you happy w the star shape or not?


Since I upgraded the guide camera, I haven focused in imaging until I improve guiding. I know this question was coming, I did take only one 300 sec exposure at unity gain with and -3 degres C. With my Zwo 533. I was not able to upload it to my other comp and see it in Pixinsight. But I am assuming results wont be great with RMS aRound 2 arcsecs
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#10 Tapio

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Posted 20 September 2020 - 06:43 AM

Pixel scale doesn't sound right.
Balancing east heavy is something you could try.
But in the end - how does your stars look like?

#11 EEBA

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Posted 20 September 2020 - 06:47 AM

You put 100% aggression for RA. You are over-correcting like crazy. Look at the saw-tooth shape of your RA. Lower it to 50-60 and increase your exposure time.

I did, and then I went decreasing slowly until 5% . I tested alot with the settings.
The one I used at the end was RA agression 50% histerysm 12 min move 0.20 .
Dec agression 80% , min move 0.25

#12 imtl

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Posted 20 September 2020 - 06:48 AM

Pixel scale doesn't sound right.
Balancing east heavy is something you could try.
But in the end - how does your stars look like?

Why? his guide scale (pixel scale) is 2.99. That is what is supposed to be.



#13 imtl

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Posted 20 September 2020 - 06:57 AM

I did, and then I went decreasing slowly until 5% . I tested alot with the settings.
The one I used at the end was RA agression 50% histerysm 12 min move 0.20 .
Dec agression 80% , min move 0.25

A few things. 

 

1. When someone says I tested a lot with the settings usually it means that the person was just going all over the place trying to magically find parameters that work. I'm not saying you did that, I'm just saying from experience.

 

2. Going down to 5% means that you are probably doing what I mentioned in 1.

 

3. Putting min mo of 0.2 in RA when you are at 0.62pixels rms means that you are just overcorrecting like crazy. Add that to your short exposures and high aggression, yields bad guiding.

 

I strongly suggest that if you want to get your guiding in order then start by running the guiding assistance, accept the parameters its suggesting, and let the system go for a while. Not two minutes and then get stressed and change parameters all over the place. Just let it be. Do 3 seconds exposures or middle of the range that GA in PHD2 recommends. So basically start from scratch and accept the initial parameters it tells you. And leave it alone!

 

You'll get good guiding eventually. Your imaging setup is very forgiving. You do not need sub arcsec guiding even. 



#14 EEBA

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Posted 20 September 2020 - 07:10 AM

A few things.

1. When someone says I tested a lot with the settings usually it means that the person was just going all over the place trying to magically find parameters that work. I'm not saying you did that, I'm just saying from experience.

2. Going down to 5% means that you are probably doing what I mentioned in 1.

3. Putting min mo of 0.2 in RA when you are at 0.62pixels rms means that you are just overcorrecting like crazy. Add that to your short exposures and high aggression, yields bad guiding.

I strongly suggest that if you want to get your guiding in order then start by running the guiding assistance, accept the parameters its suggesting, and let the system go for a while. Not two minutes and then get stressed and change parameters all over the place. Just let it be. Do 3 seconds exposures or middle of the range that GA in PHD2 recommends. So basically start from scratch and accept the initial parameters it tells you. And leave it alone!

You'll get good guiding eventually. Your imaging setup is very forgiving. You do not need sub arcsec guiding even.


I used the recommended parameters from GA about 4 different times tonight. It didn't improve.

The worse issue seems to be in the RA.
I also thought it was over correcting, that's why I decreased it from 100 all the way to 5, obviously, it didn't work. Then I bumped it up to 50%.

What is causing in the mount this wave like repetitive pattern (please open the link at beginning to se the picture)?

When I followed the GA parameters I tested for 5 to 10 min each time.
How long do I have to wait to see results?

#15 imtl

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Posted 20 September 2020 - 07:16 AM

I looked at your image and you are over correcting but I cannot see any parameters. I asked you to upload your log file. Posting parts here do not show the full picture since we cannot relate what you posted here to what was actually going on at the time.

As I mentioned your RA aggressiveness in the picture was very high. Going down to 5% is not the way to go. 50% is fine for most times. 

 

What did GA suggest for the parameters?

 

If you want more help I encourage you to upload the log file.



#16 EEBA

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Posted 20 September 2020 - 07:26 AM

I looked at your image and you are over correcting but I cannot see any parameters. I asked you to upload your log file. Posting parts here do not show the full picture since we cannot relate what you posted here to what was actually going on at the time.
As I mentioned your RA aggressiveness in the picture was very high. Going down to 5% is not the way to go. 50% is fine for most times.

What did GA suggest for the parameters?

If you want more help I encourage you to upload the log file.


I took some snaps to GA recommendations.
One says . Exposure 1.5 to 3.5 sec.
RA min move 0.26
Dec min move 0.40
Let me see if I can upload the log here. I never done it. Hold on

#17 imtl

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Posted 20 September 2020 - 07:29 AM

Just upload it to google drive and post a link. Or something like that



#18 EEBA

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Posted 20 September 2020 - 07:42 AM

I copied and oated one whole file. Also I am uploading a one drive file.

#19 EEBA

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Posted 20 September 2020 - 07:47 AM

 https://1drv.ms/t/s!...ls3jcX?e=wB3ZZH

 

 

https://1drv.ms/t/s!...hYRbx7?e=25rBR1



#20 imtl

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Posted 20 September 2020 - 08:14 AM

I looked at your second file which is the more relevant with the ASI290. You got 0.97" rms for 2.5 hours session. That is half your image scale. Your RA rms was 0.8 and Dec was 0.55. So what is the problem I don't understand?



#21 EEBA

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Posted 20 September 2020 - 08:19 AM

I looked at your second file which is the more relevant with the ASI290. You got 0.97" rms for 2.5 hours session. That is half your image scale. Your RA rms was 0.8 and Dec was 0.55. So what is the problem I don't understand?

Oh no,
That file is old from August , when I was using the zwo asi 120 mc. And guiding around 0.7 sec exposure. I got the asi 290 camera 3 days ago. Sorry. I was in from of the laptop all night, it was almost around RMS 2 .

#22 EEBA

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Posted 20 September 2020 - 08:31 AM

https://1drv.ms/t/s!...29lhEG?e=7wsryW

 

this is the other I believe from new camera this morning



#23 imtl

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Posted 20 September 2020 - 08:43 AM

Yes it was my mistake regarding the previous file. I looked into the new one you uploaded. You repeat calibration 5 times. Why? Calibration is not your problem. You keep changing parameters constantly. I repeat what I wrote before. Extend the exposure time because now your pixels are smaller and you are even more sensitive to seeing with the short exposures you're doing.

 

By the way, when you put in the new camera. Did you start a fresh profile in PHD2? If not then do that. Just delete the old one and start a new one and put in all the correct guide camera parameters etc.



#24 EEBA

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Posted 20 September 2020 - 08:58 AM

Yes it was my mistake regarding the previous file. I looked into the new one you uploaded. You repeat calibration 5 times. Why? Calibration is not your problem. You keep changing parameters constantly. I repeat what I wrote before. Extend the exposure time because now your pixels are smaller and you are even more sensitive to seeing with the short exposures you're doing.

By the way, when you put in the new camera. Did you start a fresh profile in PHD2? If not then do that. Just delete the old one and start a new one and put in all the correct guide camera parameters etc.


Yes sir, actually ,I uninstalled phd2 and installed it again to start from scratch.
You think, it is a parameters issue?
I thought there is something wrong with the mount.
I calibrated different times in different cases. For example:
Only aimeng some star close to equator and meridian.
Slewing north before calibration.
Slewing south before calibration.
Calibrating while I was guiding at 2 sec.
Calibrating while I was guiding at 4 sec.

I wish there were classes about these things. It would be easier.
I appreciate your help and this forum.
In conclusion , you recomend to follow GA parameters for a good couple hours to see results?

#25 imtl

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Posted 20 September 2020 - 09:09 AM

Hmmm... its hard to say if there is a problem with your mount. You had previously guided 0.97" so I don't think there is any fundamental issue here. I don't see any big spikes or something out of the ordinary. Just looks like parameters are not good and you are over-correcting a lot. Good chance it is do to seeing but not only.

 

I think you should use longer than 1 second exposure in my opinion. You can set your minmo to 0.3 and you will still be plenty fine with your 1.8 image scale. Use 40-50% aggression and just let it be. You do not need to worry about sub arcsec rms guiding. If it is 1-1.2" then you're fine and there is no point in stressing over it (I know you now got 1.8 rms with your new camera. This is just probably parameters need tweaking). What is important is how do you images look like? tight round stars? Then you're fine. Guiding is not there to be the main event in an imaging session. Its there to take your mind of the variance in the tracking of your mount.




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