Poor Image Stacking

Discuss how you are able to get those fantastic images!!!
Post Reply
User avatar
Graeme1858 Great Britain
Co-Administrator
Co-Administrator
Articles: 1
Online
Posts: 7217
Joined: Mon Jun 24, 2019 7:16 pm
4
Location: North Kent, UK
Status:
Online

TSS Awards Badges

TSS Photo of the Day

I Broke The Forum.

Poor Image Stacking

#1

Post by Graeme1858 »


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
______________________________________________
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/
User avatar
Larry 1969 United States of America
Milky Way Ambassador
Articles: 0
Offline
Posts: 1481
Joined: Fri May 17, 2019 12:33 am
4
Location: Pittsburgh PA USA
Status:
Offline

TSS Photo of the Day

Re: Poor Image Stacking

#2

Post by Larry 1969 »


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
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
Image
User avatar
JayTee United States of America
Universal Ambassador
Articles: 2
Offline
Posts: 5619
Joined: Thu Apr 25, 2019 3:23 am
4
Location: Idaho, USA
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: Poor Image Stacking

#3

Post by JayTee »


When you go into the DSS config, what stacking routine have you selected?

JT
∞ Primary Scopes: #1: Celestron CPC1100 #2: 8" f/7.5 Dob #3: CR150HD f/8 6" frac
∞ AP Scopes: #1: TPO 6" f/9 RC #2: ES 102 f/7 APO #3: ES 80mm f/6 APO
∞ G&G Scopes: #1: Meade 102mm f/7.8 #2: Bresser 102mm f/4.5
∞ Guide Scopes: 70 & 80mm fracs -- The El Cheapo Bros.
∞ Mounts: iOptron CEM70AG, SW EQ6, Celestron AVX, SLT & GT (Alt-Az), Meade DS2000
∞ Cameras: #1: ZWO ASI294MC Pro #2: 662MC #3: 120MC, Canon T3i, Orion SSAG, WYZE Cam3
∞ Binos: 10X50,11X70,15X70, 25X100
∞ EPs: ES 2": 21mm 100° & 30mm 82° Pentax XW: 7, 10, 14, & 20mm 70°

Searching the skies since 1966. "I never met a scope I didn't want to keep."

Image
User avatar
Graeme1858 Great Britain
Co-Administrator
Co-Administrator
Articles: 1
Online
Posts: 7217
Joined: Mon Jun 24, 2019 7:16 pm
4
Location: North Kent, UK
Status:
Online

TSS Awards Badges

TSS Photo of the Day

I Broke The Forum.

Re: Poor Image Stacking

#4

Post by Graeme1858 »


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 DSS.

I use APT for capturing and it was dithering between frames but now you mention it, it doesn't now! I must have tweaked something and then forgot! I saw that video, there is a lot of information in it. Perhaps I'll watch it again.

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/
User avatar
Graeme1858 Great Britain
Co-Administrator
Co-Administrator
Articles: 1
Online
Posts: 7217
Joined: Mon Jun 24, 2019 7:16 pm
4
Location: North Kent, UK
Status:
Online

TSS Awards Badges

TSS Photo of the Day

I Broke The Forum.

Re: Poor Image Stacking

#5

Post by Graeme1858 »


JayTee wrote: Sat May 16, 2020 12:08 am When you go into the DSS config, what stacking routine have you selected?

JT

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/
User avatar
Graeme1858 Great Britain
Co-Administrator
Co-Administrator
Articles: 1
Online
Posts: 7217
Joined: Mon Jun 24, 2019 7:16 pm
4
Location: North Kent, UK
Status:
Online

TSS Awards Badges

TSS Photo of the Day

I Broke The Forum.

Re: Poor Image Stacking

#6

Post by Graeme1858 »


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
______________________________________________
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/
User avatar
Larry 1969 United States of America
Milky Way Ambassador
Articles: 0
Offline
Posts: 1481
Joined: Fri May 17, 2019 12:33 am
4
Location: Pittsburgh PA USA
Status:
Offline

TSS Photo of the Day

Re: Poor Image Stacking

#7

Post by Larry 1969 »


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 get DSS 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
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
Image
User avatar
Graeme1858 Great Britain
Co-Administrator
Co-Administrator
Articles: 1
Online
Posts: 7217
Joined: Mon Jun 24, 2019 7:16 pm
4
Location: North Kent, UK
Status:
Online

TSS Awards Badges

TSS Photo of the Day

I Broke The Forum.

Re: Poor Image Stacking

#8

Post by Graeme1858 »


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
______________________________________________
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/
User avatar
Larry 1969 United States of America
Milky Way Ambassador
Articles: 0
Offline
Posts: 1481
Joined: Fri May 17, 2019 12:33 am
4
Location: Pittsburgh PA USA
Status:
Offline

TSS Photo of the Day

Re: Poor Image Stacking

#9

Post by Larry 1969 »


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.
You also mentioned dithering wasn't working... I suspect that's because it wasn't guiding...

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
Image
User avatar
STEVE333 United States of America
Inter-Galactic Ambassador
Articles: 0
Offline
Posts: 3466
Joined: Sat May 11, 2019 5:01 pm
4
Location: Santa Cruz, Ca, USA
Status:
Offline

TSS Awards Badges

TSS Photo of the Day

Re: Poor Image Stacking

#10

Post by STEVE333 »


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
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.

Hope this helps.

Steve
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii + iOptron CEM40 EC + Orion Magnificent Mini AutoGuider
Camera: ASI 1600MM Pro + EFW Filter Wheel + Chroma 3nm Siii, Ha, Oiii + ZWO LRGB Filters
Software: PHD2; APT; PixInsight ***** My AP website: www.steveking.pictures
Image
Image
User avatar
Graeme1858 Great Britain
Co-Administrator
Co-Administrator
Articles: 1
Online
Posts: 7217
Joined: Mon Jun 24, 2019 7:16 pm
4
Location: North Kent, UK
Status:
Online

TSS Awards Badges

TSS Photo of the Day

I Broke The Forum.

Re: Poor Image Stacking

#11

Post by Graeme1858 »


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
______________________________________________
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/
Post Reply

Create an account or sign in to join the discussion

You need to be a member in order to post a reply

Create an account

Not a member? register to join our community
Members can start their own topics & subscribe to topics
It’s free and only takes a minute

Register

Sign in

Return to “Image processing”