Why do my darks look like this?

Discuss how you are able to get those fantastic images!!!
Post Reply
Larry 1969
Orion Spur Ambassador
Articles: 0
Posts: 765
Joined: Fri May 17, 2019 12:33 am
1
Location: Pittsburgh PA USA

TSS Photo of the Day

Why do my darks look like this?

#1

Post by Larry 1969 »

Good day all!
I've been struggling with uneven illumination of my background and I think it may be due to my dark frames...
I don't understand why they look like this. By looking at my stretched master dark I would say there was a light leak but I cooled the camera to -10C and my rig was in my garage with no lights on and it was completely dark outside so, aside from the illuminated rocker switch on my power supply, there was no ambient light...

Attached are 2 screenshots. 1 is my stacked image with auto-stretch and normalization applied and the other is my master dark with the same stretch.

Any suggestions?

Thanks!

Larry
Attachments
Screenshot (20).png
Screenshot (21).png
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
Explore Scientific HR coma corrector
Altair Hypercam 26C
Larry 1969
Orion Spur Ambassador
Articles: 0
Posts: 765
Joined: Fri May 17, 2019 12:33 am
1
Location: Pittsburgh PA USA

TSS Photo of the Day

Re: Why do my darks look like this?

#2

Post by Larry 1969 »

I re-stacked this image without the darks and it turned out much better...
I'm going to re-shoot them tonight and see if I can figure out what's going on...

Larry
Attachments
Screenshot (23).png
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
Explore Scientific HR coma corrector
Altair Hypercam 26C
User avatar
STEVE333
Local Group Ambassador
Articles: 0
Posts: 2059
Joined: Sat May 11, 2019 5:01 pm
2
Location: Santa Cruz, Ca, USA

TSS Awards Badges

TSS Photo of the Day

Re: Why do my darks look like this?

#3

Post by STEVE333 »

It definitely look much better Larry. I've never had problems with Darks and, from the description of your approach, there is nothing that appears wrong. Hopefully your problem is a "one of" that goes away.

Best of success in your troubleshooting!

Steve
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii or ES ED102 CF + 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
Larry 1969
Orion Spur Ambassador
Articles: 0
Posts: 765
Joined: Fri May 17, 2019 12:33 am
1
Location: Pittsburgh PA USA

TSS Photo of the Day

Re: Why do my darks look like this?

#4

Post by Larry 1969 »

STEVE333 wrote: Mon May 03, 2021 2:32 am It definitely look much better Larry. I've never had problems with Darks and, from the description of your approach, there is nothing that appears wrong. Hopefully your problem is a "one of" that goes away.

Best of success in your troubleshooting!

Steve
Thanks Steve. I took care to cover the power supply and wrapped the focuser. I'll re-stack everything tonight.

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
Explore Scientific HR coma corrector
Altair Hypercam 26C
User avatar
bobharmony
Milky Way Ambassador
Articles: 0
Posts: 1493
Joined: Sun May 12, 2019 1:11 pm
2
Location: Connecticut, US

TSS Photo of the Day

Re: Why do my darks look like this?

#5

Post by bobharmony »

When I first looked at it I was thinking some sort of amp glow, but seeing how the darks over-corrected the lights, that is out the window. With that in mind some sort of light leak seems more likely. It'll be interesting to see if the new darks behave better.

Bob
Hardware: Celestron C6-N w/ Advanced GTmount, Baader MK iii CC, Orion ST-80, Canon 60D (unmodded), Nikon D5300 (modded), Orion SSAG
Software: BYE, APT, PHD2, DSS, PhotoShop CC 2020, StarTools, Cartes du Ciel, AstroTortilla

Image
User avatar
sdbodin
Orion Spur Ambassador
Articles: 0
Posts: 712
Joined: Sat May 11, 2019 11:00 pm
2
Location: Mattawa, WA, USA

TSS Awards Badges

TSS Photo of the Day

Re: Why do my darks look like this?

#6

Post by sdbodin »

Why mess with them, I don't. All my galaxy season shots are 'naked', no darks, flats, bias, or the latest mess-up-your-image-of-the-day method. These new cameras are almost idiot proof, and I'm the proof.

Good luck,
Steve
Scopes; Meade 16 LX200, AT80LE, plus bunch just sitting around gathering dust
Cameras; Atik 460ex mono, Zwo ASI1600MC-cool, QHY5L-II color and mono
Larry 1969
Orion Spur Ambassador
Articles: 0
Posts: 765
Joined: Fri May 17, 2019 12:33 am
1
Location: Pittsburgh PA USA

TSS Photo of the Day

Re: Why do my darks look like this?

#7

Post by Larry 1969 »

sdbodin wrote: Mon May 03, 2021 3:10 pm Why mess with them, I don't. All my galaxy season shots are 'naked', no darks, flats, bias, or the latest mess-up-your-image-of-the-day method. These new cameras are almost idiot proof, and I'm the proof.

Good luck,
Steve
I've been debating the necessity of dark frames lately myself... I have an Altair 26C that has very low read noise and zero amp glow...
I've only been at this for about 2 years but I started out with a DSLR and they were necessary and I just got in the habit...

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
Explore Scientific HR coma corrector
Altair Hypercam 26C
User avatar
STEVE333
Local Group Ambassador
Articles: 0
Posts: 2059
Joined: Sat May 11, 2019 5:01 pm
2
Location: Santa Cruz, Ca, USA

TSS Awards Badges

TSS Photo of the Day

Re: Why do my darks look like this?

#8

Post by STEVE333 »

Larry 1969 wrote: Mon May 03, 2021 9:46 pm
sdbodin wrote: Mon May 03, 2021 3:10 pm Why mess with them, I don't. All my galaxy season shots are 'naked', no darks, flats, bias, or the latest mess-up-your-image-of-the-day method. These new cameras are almost idiot proof, and I'm the proof.

Good luck,
Steve
I've been debating the necessity of dark frames lately myself... I have an Altair 26C that has very low read noise and zero amp glow...
I've only been at this for about 2 years but I started out with a DSLR and they were necessary and I just got in the habit...

Larry
Getting away without Darks maybe, but, for my system the Flats are a necessity. Not only do I have Amp Glow but the corners of my image are darker than the center, so, Flats help my images quite a bit.

Just sayin -

Steve
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii or ES ED102 CF + 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
Larry 1969
Orion Spur Ambassador
Articles: 0
Posts: 765
Joined: Fri May 17, 2019 12:33 am
1
Location: Pittsburgh PA USA

TSS Photo of the Day

Re: Why do my darks look like this?

#9

Post by Larry 1969 »

STEVE333 wrote: Mon May 03, 2021 10:50 pm
Getting away without Darks maybe, but, for my system the Flats are a necessity. Not only do I have Amp Glow but the corners of my image are darker than the center, so, Flats help my images quite a bit.

Just sayin -

Steve
For sure Steve! I would need flats and I would, most likely, shoot dark flats just because they're quick and easy.

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
Explore Scientific HR coma corrector
Altair Hypercam 26C
Larry 1969
Orion Spur Ambassador
Articles: 0
Posts: 765
Joined: Fri May 17, 2019 12:33 am
1
Location: Pittsburgh PA USA

TSS Photo of the Day

Re: Why do my darks look like this?

#10

Post by Larry 1969 »

Well, I just re-stacked the image with the new darks and it looks much like the image with no darks at all...
Here's the image followed by the new master dark... I may quit shooting darks entirely...
Although it begs the question: If my darks are suffering from light leakage, my light frames are surely as well, are they not?
I'm going to take more precaution when shooting my lights and I may or may not shoot darks...

Thanks for the feedback!

Larry
Attachments
Screenshot (24).png
Screenshot (25).png
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
Explore Scientific HR coma corrector
Altair Hypercam 26C
User avatar
STEVE333
Local Group Ambassador
Articles: 0
Posts: 2059
Joined: Sat May 11, 2019 5:01 pm
2
Location: Santa Cruz, Ca, USA

TSS Awards Badges

TSS Photo of the Day

Re: Why do my darks look like this?

#11

Post by STEVE333 »

Congratulations on resolving your Darks issue.

Since your camera is CMOS your idea of using dark flats is the correct one. With CMOS sensors it is recommended NOT to use Bias frames but to use dark flats for flat frames.

Steve
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii or ES ED102 CF + 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
User avatar
XCalRocketMan
Saturn Ambassador
Articles: 0
Posts: 308
Joined: Sun May 12, 2019 8:09 pm
2
Location: Reisterstown, MD USA
Contact:

TSS Awards Badges

TSS Photo of the Day

Re: Why do my darks look like this?

#12

Post by XCalRocketMan »

Larry 1969 wrote: Mon May 03, 2021 11:59 pm
STEVE333 wrote: Mon May 03, 2021 10:50 pm
Getting away without Darks maybe, but, for my system the Flats are a necessity. Not only do I have Amp Glow but the corners of my image are darker than the center, so, Flats help my images quite a bit.

Just sayin -

Steve
For sure Steve! I would need flats and I would, most likely, shoot dark flats just because they're quick and easy.

Larry
Very interesting dialog here as I was just thinking to myself about the need for darks with my ASI2600. Flats yes, since I have vignetting and you can't remove dust shadows without them. I need to do some experimenting.
Scopes/Mounts Celestron EdgeHD-11 on AP1100GTO mount w/APCCpro; William Optics GT102 on iOptron iEQ30 Pro; Criterion Dynamax-8 SCT
Lenses Hyperstar-III; Celestron 0.7x FR; WO Flat/Reducer 0.8x
Guiding Celestron OAG w/ASI174mm mini; Orion ST80; WO 50mm
Cameras and Filters ZWOASI1600mm Pro (ZWO LRGB and Astrodon Ha-5nm, Oiii-3nm, Sii-5nm), QHY10, Canon 50D; ASI174mm mini; ASI462MC; ASI120MC
Misc Moonlite focuser on Edge - Feather-Touch focuser on iOptron; ZWO 31mm FW; Kendrick Dew System, Temp-est Fans
Software SN8; SGP; APT; BYE; PHD; MG; FlexRX; PSP; PI; Registax; FireCapture; SharpCap
User avatar
bobharmony
Milky Way Ambassador
Articles: 0
Posts: 1493
Joined: Sun May 12, 2019 1:11 pm
2
Location: Connecticut, US

TSS Photo of the Day

Re: Why do my darks look like this?

#13

Post by bobharmony »

Larry 1969 wrote: Mon May 03, 2021 9:46 pm
I've been debating the necessity of dark frames lately myself... I have an Altair 26C that has very low read noise and zero amp glow...
I've only been at this for about 2 years but I started out with a DSLR and they were necessary and I just got in the habit...

Larry
Even with the Canon DSLR, I have been debating the need for dark frames. With enough dither positions and a lot of lights, I'm not sure how helpful they are. Still working out that detail on the Nikon.

Like Steve, I rely on flats to handle vignetting and dust.

Bob
Hardware: Celestron C6-N w/ Advanced GTmount, Baader MK iii CC, Orion ST-80, Canon 60D (unmodded), Nikon D5300 (modded), Orion SSAG
Software: BYE, APT, PHD2, DSS, PhotoShop CC 2020, StarTools, Cartes du Ciel, AstroTortilla

Image
User avatar
Graeme1858
Co-Administrator
Articles: 0
Posts: 3938
Joined: Mon Jun 24, 2019 7:16 pm
1
Location: North Kent, UK

TSS Awards Badges

TSS Photo of the Day

I Broke The Forum.

Re: Why do my darks look like this?

#14

Post by Graeme1858 »

I hope you get to the bottom of your dark frame issue Larry.

Here's one of my darks, stretched. The 294MC sensor does this every time! I only use 10 darks in the stack but the amp glow shows if I don't use any.

Regards

Graeme
Attachments
Stretched dark frame.jpg
______________________________________________
Click Here for the AP Processing Challenge!
______________________________________________
Celestron 9.25 f10 SCT, CGX mount.
ZWO ASI294MC Pro, Canon 600D, Altair GPCAM2 290C.
Celestron 80mm Guidescope, QHY5-II Mono.
Miranda 10x50 Binoculars.
Image
Larry 1969
Orion Spur Ambassador
Articles: 0
Posts: 765
Joined: Fri May 17, 2019 12:33 am
1
Location: Pittsburgh PA USA

TSS Photo of the Day

Re: Why do my darks look like this?

#15

Post by Larry 1969 »

Graeme1858 wrote: Tue May 04, 2021 5:34 am I hope you get to the bottom of your dark frame issue Larry.
The 294MC sensor does this every time! I only use 10 darks in the stack but the amp glow shows if I don't use any.

Regards

Graeme
Unfortunately, I believe dark frames are the only way to handle amp glow...
Maybe there's a new camera in your future?

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
Explore Scientific HR coma corrector
Altair Hypercam 26C
User avatar
Graeme1858
Co-Administrator
Articles: 0
Posts: 3938
Joined: Mon Jun 24, 2019 7:16 pm
1
Location: North Kent, UK

TSS Awards Badges

TSS Photo of the Day

I Broke The Forum.

Re: Why do my darks look like this?

#16

Post by Graeme1858 »

Larry 1969 wrote: Tue May 04, 2021 10:32 am Maybe there's a new camera in your future?

I wish!
______________________________________________
Click Here for the AP Processing Challenge!
______________________________________________
Celestron 9.25 f10 SCT, CGX mount.
ZWO ASI294MC Pro, Canon 600D, Altair GPCAM2 290C.
Celestron 80mm Guidescope, QHY5-II Mono.
Miranda 10x50 Binoculars.
Image
Post Reply

Return to “Image processing”