Poor Image Stacking
- Graeme1858
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Poor Image Stacking
My image of the M61 supernova is a single 900 second shot (viewtopic.php?f=9&t=9913#p85121)
On the night I actually captured 9 x 900 second images. My collimation was good because I had just corrected it, my guiding was the best I've ever seen (RMS 0.63) almost flat line! and the Polar alignment was checked and adjusted a few nights earlier.
My problem is that whilst each image is good with round stars, each image is just a tad moved over from the last. As a result the stacked image is just a blur. It looks like the result I used to get when stacking 30 second captures with poor Polar Alignment. I would have thought that if my problem was Polar Alignment then the guiding would not be so error free.
Anyone got any clues?
Regards
Graeme
On the night I actually captured 9 x 900 second images. My collimation was good because I had just corrected it, my guiding was the best I've ever seen (RMS 0.63) almost flat line! and the Polar alignment was checked and adjusted a few nights earlier.
My problem is that whilst each image is good with round stars, each image is just a tad moved over from the last. As a result the stacked image is just a blur. It looks like the result I used to get when stacking 30 second captures with poor Polar Alignment. I would have thought that if my problem was Polar Alignment then the guiding would not be so error free.
Anyone got any clues?
Regards
Graeme
______________________________________________
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
- Larry 1969
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Re: Poor Image Stacking
Are you using DSS for stacking? It sounds like one or multiple settings are wrong.
I dither between frames which results in my target dancing all around andDSS stacks them just fine.
The post right above this has a link to a tutorial forDSS . Might be worth a watch.
I just emailed that link to myself for future reference.
Larry
I dither between frames which results in my target dancing all around and
The post right above this has a link to a tutorial for
I just emailed that link to myself for future reference.
Larry
For visual:
10" Skywatcher collapsible goto dob, various EP's and a Celestron StarSense auto align.
For imaging:
Orion 8" astrograph 800mm @ F3.9
Eq6-R Pro controlled by APT via EQmod with an OTA mounted mini PC
Tele Vue Paracorr Type 2 coma corrector
Altair Hypercam 26C
10" Skywatcher collapsible goto dob, various EP's and a Celestron StarSense auto align.
For imaging:
Orion 8" astrograph 800mm @ F3.9
Eq6-R Pro controlled by APT via EQmod with an OTA mounted mini PC
Tele Vue Paracorr Type 2 coma corrector
Altair Hypercam 26C
- JayTee
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Re: Poor Image Stacking
When you go into the DSS config, what stacking routine have you selected?
JT
JT
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- Graeme1858
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Re: Poor Image Stacking
Larry 1969 wrote: ↑Fri May 15, 2020 2:05 pm Are you using DSS for stacking? It sounds like one or multiple settings are wrong.
I dither between frames which results in my target dancing all around and DSS stacks them just fine.
The post right above this has a link to a tutorial for DSS. Might be worth a watch.
I just emailed that link to myself for future reference.
Larry
Hello Larry, thanks for your reply.
Yes I use
I use
Thanks
Regards
Graeme
______________________________________________
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
- Graeme1858
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Re: Poor Image Stacking
Hello JT.
If I open the files and register them, the Stacking Parameters Alignment tab tells me the Transformation used during alignment is Bilinear. It's the default setting, I don't think I have ever changed it.
Is that the one you mean?
I've changed the camera from generic to Rebel Xti after watching the video Larry posted a link to above and unticked the drizzle x3 box. Just trying a re-stack now.
Regards
Graeme
______________________________________________
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
- Graeme1858
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Re: Poor Image Stacking
Just stacked M61 again and got the same result. Then I stacked some data from last night of M101 and it turned out ok!
Perhaps 900 second subs is too long. It was a bit of an experimental night after playing with the collimation, just to see how long it would accurately guide.
Regards
Graeme
Perhaps 900 second subs is too long. It was a bit of an experimental night after playing with the collimation, just to see how long it would accurately guide.
Regards
Graeme
______________________________________________
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
- Larry 1969
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Re: Poor Image Stacking
After you register those frames go to the "Advanced" tab. There is a slider that you can change from 2% to 100%.
I adjust this slider and hit "Compute number of stars" and keep adjusting until I get around 100 to 200.
This will vary depending on what part of the sky you're imaging.
Let us know how many stars you can getDSS to detect.
I just looked at your single image and the stars are trailing a bit...DSS really doesn't like that...
900 sec is probably too long. I've been having pretty good success with 180 sec ecposures.
Larry
I adjust this slider and hit "Compute number of stars" and keep adjusting until I get around 100 to 200.
This will vary depending on what part of the sky you're imaging.
Let us know how many stars you can get
I just looked at your single image and the stars are trailing a bit...
900 sec is probably too long. I've been having pretty good success with 180 sec ecposures.
Larry
For visual:
10" Skywatcher collapsible goto dob, various EP's and a Celestron StarSense auto align.
For imaging:
Orion 8" astrograph 800mm @ F3.9
Eq6-R Pro controlled by APT via EQmod with an OTA mounted mini PC
Tele Vue Paracorr Type 2 coma corrector
Altair Hypercam 26C
10" Skywatcher collapsible goto dob, various EP's and a Celestron StarSense auto align.
For imaging:
Orion 8" astrograph 800mm @ F3.9
Eq6-R Pro controlled by APT via EQmod with an OTA mounted mini PC
Tele Vue Paracorr Type 2 coma corrector
Altair Hypercam 26C
- Graeme1858
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Re: Poor Image Stacking
I usually set the slider to 200 or 300 stars. Yes, there is a slight trail, not sure how if the guiding is good. I suspect you're right about the exposure duration, it was a bit experimental.
Oh well, I've added M61 to myMessier list collection anyway! And I've posted my M101 from last night in the May Challenge.
Cheers
Regards
Graeme
Oh well, I've added M61 to my
Cheers
Regards
Graeme
______________________________________________
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
- Larry 1969
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Re: Poor Image Stacking
You also mentioned dithering wasn't working... I suspect that's because it wasn't guiding...Graeme1858 wrote: ↑Sat May 16, 2020 1:28 pm I usually set the slider to 200 or 300 stars. Yes, there is a slight trail, not sure how if the guiding is good. I suspect you're right about the exposure duration, it was a bit experimental.
ALL of my imaging sessions have been "experimental"! New problems always arise. That's the challenge!
Clear skies!
Larry
For visual:
10" Skywatcher collapsible goto dob, various EP's and a Celestron StarSense auto align.
For imaging:
Orion 8" astrograph 800mm @ F3.9
Eq6-R Pro controlled by APT via EQmod with an OTA mounted mini PC
Tele Vue Paracorr Type 2 coma corrector
Altair Hypercam 26C
10" Skywatcher collapsible goto dob, various EP's and a Celestron StarSense auto align.
For imaging:
Orion 8" astrograph 800mm @ F3.9
Eq6-R Pro controlled by APT via EQmod with an OTA mounted mini PC
Tele Vue Paracorr Type 2 coma corrector
Altair Hypercam 26C
- STEVE333
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Re: Poor Image Stacking
Hi Graeme - If your guiding is good (yours was excellent!) and there is still some star trailing, then, the problem is with the Polar Alignment. Even with perfect guiding there will be trailing if the Polar alignment is off. The trailing should get worse as you move away from the star you used for guiding. The star used for guiding should be nearly perfect.Graeme1858 wrote: ↑Sat May 16, 2020 1:28 pm I usually set the slider to 200 or 300 stars. Yes, there is a slight trail, not sure how if the guiding is good. I suspect you're right about the exposure duration, it was a bit experimental.
Oh well, I've added M61 to my Messier list collection anyway! And I've posted my M101 from last night in the May Challenge.
Cheers
Regards
Graeme
Hope this helps.
Steve
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- Graeme1858
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Re: Poor Image Stacking
Thanks Steve.
There's a possibility that I was lulled into a false sense of security thinking that slight polar alignment inaccuracies would be sorted by the guiding!
I'll check it before my next outing.
Regards
Graeme
There's a possibility that I was lulled into a false sense of security thinking that slight polar alignment inaccuracies would be sorted by the guiding!
I'll check it before my next outing.
Regards
Graeme
______________________________________________
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.
https://www.averywayobservatory.co.uk/
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