Bad images _Bouncing stars


 

Hi John

i'm a regular contributor in the PHD forums https://groups.google.com/forum/?fromgroups=#!forum/open-phd-guiding 

it's difficult to give meaningful input without looking at the guidelogs. I highly recommend capturing a solid baseline guiding and then posting it in the forums there with any questions you may have.

if you don't have a solid baseline, i put a guide together to create one for the PHD forums, you can follow those steps and produce something that is really good for analysis and feedback:  



On Fri, May 1, 2020 at 4:51 PM John Thompson via groups.io <jbtgolfer=yahoo.com@groups.io> wrote:
This is a follow up to my "Bouncing Stars" post. I imaged the next night (with and without guiding) for 1200 sec exposures. The images were fine (round stars) no zig-zag patterns or elongated stars. I did notice a slight oblong effect in the unguided image. Looking at  PHD2 graphics it appears I have some drift in RA that I must correct. All my RA corrections were on the same side of the graph.I believe that signifies an RA drift ? Looking at my PHD2 log from night one I see a frequent occurrence of "guide star lost" either for low SNR or low Star mass. I assume that losing the guide star for long periods means large sudden corrections and the "bouncing" I described. In any case I am attributing the primary cause of the problem to the guiding software either due to a settings error or poor selection of guide star. I will work on a solution with PHD2. Definitely not a mount problem as proved by last nights test. If anyone has a proven set of PHD2 settings i would appreciate getting them.

Thanks for your responses.   



--
Brian 



Brian Valente


Mike Shade
 

Good to see feedback.  Not sure what your mount/imaging system is but a good test might be to see what the mount does unguided for a worm cycle...with PEC on and PEC off (you have a good PEC curve right?).  My 1600 it is a 382" period.  Asking a mount to go unguided for 20 minutes (1200 seconds), unless you have a very low resolution system is asking a lot and you will likely get some RA drift, or other errors (mirror flop, component sag, dragging cables, and optical aberrations caused by seeing variations to name a few) and this is not unexpected.  See what it does for a worm cycle.

 

Mike J. Shade

Mike J. Shade Photography:

mshadephotography.com

 

In War: Resolution

In Defeat: Defiance

In Victory: Magnanimity

In Peace: Goodwill

Sir Winston Churchill

Already, in the gathering dusk, a few of the stars are turning on their lights.

Vega, the brightest one, is now dropping towards the west.  Can it be half

a year since I watched her April rising in the east?  Low in the southwest

Antares blinks a sad farwell to fall...

Leslie Peltier, Starlight Nights

 

International Dark Sky Association: www.darksky.org

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of John Thompson via groups.io
Sent: Friday, May 01, 2020 4:51 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Bad images _Bouncing stars

 

This is a follow up to my "Bouncing Stars" post. I imaged the next night (with and without guiding) for 1200 sec exposures. The images were fine (round stars) no zig-zag patterns or elongated stars. I did notice a slight oblong effect in the unguided image. Looking at  PHD2 graphics it appears I have some drift in RA that I must correct. All my RA corrections were on the same side of the graph.I believe that signifies an RA drift ? Looking at my PHD2 log from night one I see a frequent occurrence of "guide star lost" either for low SNR or low Star mass. I assume that losing the guide star for long periods means large sudden corrections and the "bouncing" I described. In any case I am attributing the primary cause of the problem to the guiding software either due to a settings error or poor selection of guide star. I will work on a solution with PHD2. Definitely not a mount problem as proved by last nights test. If anyone has a proven set of PHD2 settings i would appreciate getting them.

Thanks for your responses.   


John Thompson <jbtgolfer@...>
 

This is a follow up to my "Bouncing Stars" post. I imaged the next night (with and without guiding) for 1200 sec exposures. The images were fine (round stars) no zig-zag patterns or elongated stars. I did notice a slight oblong effect in the unguided image. Looking at  PHD2 graphics it appears I have some drift in RA that I must correct. All my RA corrections were on the same side of the graph.I believe that signifies an RA drift ? Looking at my PHD2 log from night one I see a frequent occurrence of "guide star lost" either for low SNR or low Star mass. I assume that losing the guide star for long periods means large sudden corrections and the "bouncing" I described. In any case I am attributing the primary cause of the problem to the guiding software either due to a settings error or poor selection of guide star. I will work on a solution with PHD2. Definitely not a mount problem as proved by last nights test. If anyone has a proven set of PHD2 settings i would appreciate getting them.

Thanks for your responses.   


Mike Shade
 

As I offered I had some weirdness with my setup.  After much fidgeting and greasing the gears and a new PEC curve, I can go 382" (the worm period) and get round stars near zenith unguided.  I could go 300", but that wasn't a complete worm cycle.  This suggests strongly that the weirdness was not the mount.  A good place to start to see what your mount can do.

 

Mike J. Shade

Mike J. Shade Photography:

mshadephotography.com

 

In War: Resolution

In Defeat: Defiance

In Victory: Magnanimity

In Peace: Goodwill

Sir Winston Churchill

Already, in the gathering dusk, a few of the stars are turning on their lights.

Vega, the brightest one, is now dropping towards the west.  Can it be half

a year since I watched her April rising in the east?  Low in the southwest

Antares blinks a sad farwell to fall...

Leslie Peltier, Starlight Nights

 

International Dark Sky Association: www.darksky.org

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of John Thompson via groups.io
Sent: Tuesday, April 28, 2020 3:34 PM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Bad images _Bouncing stars

 

I apologize. I should have provided more information in my "bouncing stars"post. It's an AP 1600 mount (no Encoders) with a TEC140 F/7 scope with a FLI Atlas focuser. It's running Maxim for the main camera, SBIG STF-8300 and PHD for the guide camera, a SBIG ST-i. I am using APCC Pro with SkyX for the planetary program. The focus program is FocusMax. The session runs auto using CCDAutoPilot5. I am shooting LRGB 10 images each filter @ 600 sec using a 5 pixel dither between images. PHD is running RA and DEC in Hyperstasis with a 60 aggression setting with 3 sec exposures with dithering. Actually the guiding looks very good with very few corrections and a low RMS. I don;t believe the guide star is lost at any time but dithering might be an issue. I will look at the guide logs for any clues. The only time I see something "funny" is during the dithers. But the guiding stops during the dithers and then re-aguires the guide star.

The night was almost perfect, 5 by 5. No clouds or wind (3 MPH max) All cables are routed through the mount and appear ok.

I may try some imaging at 600 sec with no guiding tonight and some with no dithering. Thank you all for the comments. Any other ideas are appreciated.


Konstantin von Poschinger
 

Hi,

Try to give more time for recentering and use the multistar guiding in maxim.

Grüsse

Konstantin v. Poschinger


Hammerichstr. 5
22605 Hamburg
040/8805747
0171/1983476

Am 29.04.2020 um 00:34 schrieb John Thompson via groups.io <jbtgolfer@...>:

I apologize. I should have provided more information in my "bouncing stars"post. It's an AP 1600 mount (no Encoders) with a TEC140 F/7 scope with a FLI Atlas focuser. It's running Maxim for the main camera, SBIG STF-8300 and PHD for the guide camera, a SBIG ST-i. I am using APCC Pro with SkyX for the planetary program. The focus program is FocusMax. The session runs auto using CCDAutoPilot5. I am shooting LRGB 10 images each filter @ 600 sec using a 5 pixel dither between images. PHD is running RA and DEC in Hyperstasis with a 60 aggression setting with 3 sec exposures with dithering. Actually the guiding looks very good with very few corrections and a low RMS. I don;t believe the guide star is lost at any time but dithering might be an issue. I will look at the guide logs for any clues. The only time I see something "funny" is during the dithers. But the guiding stops during the dithers and then re-aguires the guide star.

The night was almost perfect, 5 by 5. No clouds or wind (3 MPH max) All cables are routed through the mount and appear ok.

I may try some imaging at 600 sec with no guiding tonight and some with no dithering. Thank you all for the comments. Any other ideas are appreciated.


John Thompson <jbtgolfer@...>
 

I apologize. I should have provided more information in my "bouncing stars"post. It's an AP 1600 mount (no Encoders) with a TEC140 F/7 scope with a FLI Atlas focuser. It's running Maxim for the main camera, SBIG STF-8300 and PHD for the guide camera, a SBIG ST-i. I am using APCC Pro with SkyX for the planetary program. The focus program is FocusMax. The session runs auto using CCDAutoPilot5. I am shooting LRGB 10 images each filter @ 600 sec using a 5 pixel dither between images. PHD is running RA and DEC in Hyperstasis with a 60 aggression setting with 3 sec exposures with dithering. Actually the guiding looks very good with very few corrections and a low RMS. I don;t believe the guide star is lost at any time but dithering might be an issue. I will look at the guide logs for any clues. The only time I see something "funny" is during the dithers. But the guiding stops during the dithers and then re-aguires the guide star.

The night was almost perfect, 5 by 5. No clouds or wind (3 MPH max) All cables are routed through the mount and appear ok.

I may try some imaging at 600 sec with no guiding tonight and some with no dithering. Thank you all for the comments. Any other ideas are appreciated.


Michael Hambrick <mike.hambrick@...>
 

OK A little more clarification. My issue was caused by using too high a guide rate. This was with my old 800 mount with the old 8010 controller with mechanical relays. It had the option to change the guide rate and mine had somehow gotten changed from 2X to 8X and I was getting all kinds of weird behavior.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        "Michael Hambrick via groups.io" <mike.hambrick@...>
To:        main@ap-gto.groups.io
Date:        2020-04-28 09:45 AM
Subject:        Re: [ap-gto] Bad images _Bouncing stars
Sent by:        main@ap-gto.groups.io




Maybe try checking your guiding aggressiveness and response. It seems that I had a similar issue once when the guider was trying to overcorrect.


Best Regards

Michael Hambrick

ARLANX
EO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        
"uncarollo2 <chris1011@...> via groups.io" <chris1011@...>
To:        
main@ap-gto.groups.io
Date:        
2020-04-28 09:22 AM
Subject:        
Re: [ap-gto] Bad images _Bouncing stars
Sent by:        
main@ap-gto.groups.io




Which guider program?

MaximDL will do a zigzag search when it loses a guide star. The result is what you show in your image. PHD may also do something similar when the guide star is lost.

Rolando



-----Original Message-----
From: John Thompson via groups.io <jbtgolfer@...>
To: main <main@ap-gto.groups.io>
Sent: Tue, Apr 28, 2020 8:44 am
Subject: [ap-gto] Bad images _Bouncing stars

I need some advice I am getting bad images 80% of the time due to "bouncing" stars. It's a zig -zag pattern. It seems to occur on the East side of my AP 1600 mount. I have attached an image. Has anyone seen this pattern and any suggestions?







Michael Hambrick <mike.hambrick@...>
 

Maybe try checking your guiding aggressiveness and response. It seems that I had a similar issue once when the guider was trying to overcorrect.


Best Regards

Michael Hambrick
ARLANXEO
TSR Global Manufacturing Support
PO Box 2000
Orange, TX 77631-2000
Phone: +1 (409) 882-2799
email: mike.hambrick@...




From:        "uncarollo2 <chris1011@...> via groups.io" <chris1011@...>
To:        main@ap-gto.groups.io
Date:        2020-04-28 09:22 AM
Subject:        Re: [ap-gto] Bad images _Bouncing stars
Sent by:        main@ap-gto.groups.io




Which guider program?

MaximDL will do a zigzag search when it loses a guide star. The result is what you show in your image. PHD may also do something similar when the guide star is lost.

Rolando



-----Original Message-----
From: John Thompson via groups.io <jbtgolfer@...>
To: main <main@ap-gto.groups.io>
Sent: Tue, Apr 28, 2020 8:44 am
Subject: [ap-gto] Bad images _Bouncing stars

I need some advice I am getting bad images 80% of the time due to "bouncing" stars. It's a zig -zag pattern. It seems to occur on the East side of my AP 1600 mount. I have attached an image. Has anyone seen this pattern and any suggestions?




Roland Christen
 

Which guider program?

MaximDL will do a zigzag search when it loses a guide star. The result is what you show in your image. PHD may also do something similar when the guide star is lost.

Rolando



-----Original Message-----
From: John Thompson via groups.io <jbtgolfer@...>
To: main <main@ap-gto.groups.io>
Sent: Tue, Apr 28, 2020 8:44 am
Subject: [ap-gto] Bad images _Bouncing stars

I need some advice I am getting bad images 80% of the time due to "bouncing" stars. It's a zig -zag pattern. It seems to occur on the East side of my AP 1600 mount. I have attached an image. Has anyone seen this pattern and any suggestions?


W Hilmo
 

I had an issue on one outing with my AP1600 (with encoders), where I would get perfectly round stars – but a handful of them each night would have faint tails.

 

It looked for all the world like a mount problem, but it turned out to be something surprising.  What has happening is that after a filter change, my focuser would move a bit due to per-filter focus offsets.  If the offset caused the filter knob to turn counter-clockwise, everything would be fine.  If the filter offset caused a clockwise turn, however, my focus motor would do a large backlash runout.  Mirror shift during the backlash compensation would push the guide star out of position in the OAG.  The tail was the result of the image capture starting before the guide star was recovered.

 

To correct the problem in my case, I needed to disable guiding during filter change.

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of Mike Shade
Sent: Tuesday, April 28, 2020 7:04 AM
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] Bad images _Bouncing stars

 

I have had a similar problem with my 1600.  I run ACP...everything runs along fine...would shoot a series of R, G, B frames.  All of them are fine except there will be several in a row where the mount oscillated in RA-the star is there but there are "ears" where it oscillated.  Intermittent, which as you know are the hardest problems to DX.  No clouds or anything.  Have you seen what you mount can do unguided as a base?  Is everything smooth meaning cables and such?  Imaging train snug?

 

Mike J. Shade

Mike J. Shade Photography:

mshadephotography.com

 

In War: Resolution

In Defeat: Defiance

In Victory: Magnanimity

In Peace: Goodwill

Sir Winston Churchill

Already, in the gathering dusk, a few of the stars are turning on their lights.

Vega, the brightest one, is now dropping towards the west.  Can it be half

a year since I watched her April rising in the east?  Low in the southwest

Antares blinks a sad farwell to fall...

Leslie Peltier, Starlight Nights

 

International Dark Sky Association: www.darksky.org

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of John Thompson via groups.io
Sent: Tuesday, April 28, 2020 6:44 AM
To: main@ap-gto.groups.io
Subject: [ap-gto] Bad images _Bouncing stars

 

I need some advice I am getting bad images 80% of the time due to "bouncing" stars. It's a zig -zag pattern. It seems to occur on the East side of my AP 1600 mount. I have attached an image. Has anyone seen this pattern and any suggestions?


 

are you guiding? if so, which guiding app


On Tue, Apr 28, 2020 at 6:44 AM John Thompson via groups.io <jbtgolfer=yahoo.com@groups.io> wrote:
I need some advice I am getting bad images 80% of the time due to "bouncing" stars. It's a zig -zag pattern. It seems to occur on the East side of my AP 1600 mount. I have attached an image. Has anyone seen this pattern and any suggestions?



--
Brian 



Brian Valente


Roland Christen
 

Need more information:

Encoder or non-encoder mount?
Which axis?

Rolando



-----Original Message-----
From: John Thompson via groups.io <jbtgolfer@...>
To: main <main@ap-gto.groups.io>
Sent: Tue, Apr 28, 2020 8:44 am
Subject: [ap-gto] Bad images _Bouncing stars

I need some advice I am getting bad images 80% of the time due to "bouncing" stars. It's a zig -zag pattern. It seems to occur on the East side of my AP 1600 mount. I have attached an image. Has anyone seen this pattern and any suggestions?


Mike Shade
 

I have had a similar problem with my 1600.  I run ACP...everything runs along fine...would shoot a series of R, G, B frames.  All of them are fine except there will be several in a row where the mount oscillated in RA-the star is there but there are "ears" where it oscillated.  Intermittent, which as you know are the hardest problems to DX.  No clouds or anything.  Have you seen what you mount can do unguided as a base?  Is everything smooth meaning cables and such?  Imaging train snug?

 

Mike J. Shade

Mike J. Shade Photography:

mshadephotography.com

 

In War: Resolution

In Defeat: Defiance

In Victory: Magnanimity

In Peace: Goodwill

Sir Winston Churchill

Already, in the gathering dusk, a few of the stars are turning on their lights.

Vega, the brightest one, is now dropping towards the west.  Can it be half

a year since I watched her April rising in the east?  Low in the southwest

Antares blinks a sad farwell to fall...

Leslie Peltier, Starlight Nights

 

International Dark Sky Association: www.darksky.org

 

From: main@ap-gto.groups.io [mailto:main@ap-gto.groups.io] On Behalf Of John Thompson via groups.io
Sent: Tuesday, April 28, 2020 6:44 AM
To: main@ap-gto.groups.io
Subject: [ap-gto] Bad images _Bouncing stars

 

I need some advice I am getting bad images 80% of the time due to "bouncing" stars. It's a zig -zag pattern. It seems to occur on the East side of my AP 1600 mount. I have attached an image. Has anyone seen this pattern and any suggestions?


Steve Reilly
 

I get this from time to time and it seems the guide star gets lost and you get these or worse results. It could have been at any point in the exposure that the clouds moved in temporarily or near the end. I have some from SRO that look like lightning strikes. Space lightning, yeah that’s what it is.

 

-Steve

 

 

From: main@ap-gto.groups.io <main@ap-gto.groups.io> On Behalf Of John Thompson via groups.io
Sent: Tuesday, April 28, 2020 9:44 AM
To: main@ap-gto.groups.io
Subject: [ap-gto] Bad images _Bouncing stars

 

I need some advice I am getting bad images 80% of the time due to "bouncing" stars. It's a zig -zag pattern. It seems to occur on the East side of my AP 1600 mount. I have attached an image. Has anyone seen this pattern and any suggestions?


John Thompson <jbtgolfer@...>
 

I need some advice I am getting bad images 80% of the time due to "bouncing" stars. It's a zig -zag pattern. It seems to occur on the East side of my AP 1600 mount. I have attached an image. Has anyone seen this pattern and any suggestions?