Return to the Cloudy Nights Telescope Reviews home page

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User

Astrophotography and Sketching >> Beginning Imaging

Pages: 1
EricJD
super member


Reged: 07/24/07
Posts: 112
Loc: Chesapeake VA
More image problems. new
      #2596815 - 08/22/08 02:40 PM

Thanks to those that solved my 'smudge' problem the other day. Today I have a new one that you can see here:



I'm using a DSI Pro and Deep Sky Stacker with Median combine, stacking lights and darks only. Any idea where the black dots are coming from?

--------------------
Orion 120mm @ f5


Post Extras: Print Post   Remind Me!   Notify Moderator  
DaemonGPF
Pooh-Bah
*****

Reged: 03/22/08
Posts: 1428
Loc: New Mexico
Re: More image problems. new [Re: EricJD]
      #2596860 - 08/22/08 03:12 PM

I get those black dots prominently when I run "Noise Despeckle" in Paintshop if I don't remove all the hot pixels in the image first. In your case though, they seem a little too frequent.. What happens when you combine in another application? Just curious.

--------------------
-Josh

*Orion Starblast Imaging 150mm OTA
*Orion Starblast Imaging 114mm OTA
*Meade 50mm AR short tube OTA
*Meade DSI Pro IIc
*Orion Starshoot DSCI
*CG5 mount
http://cleardarksky.com/c/AlbuqNMkey.html

My Messier Project Gallery


Post Extras: Print Post   Remind Me!   Notify Moderator  
DaemonGPF
Pooh-Bah
*****

Reged: 03/22/08
Posts: 1428
Loc: New Mexico
Re: More image problems. new [Re: DaemonGPF]
      #2596863 - 08/22/08 03:14 PM

Hmmm.. after saving your file and blowing it up larger, it looks more like banding, not so much spots. The bands and gaps are covering your whole file when you zoom in. I have no clue on that one, sorry.

--------------------
-Josh

*Orion Starblast Imaging 150mm OTA
*Orion Starblast Imaging 114mm OTA
*Meade 50mm AR short tube OTA
*Meade DSI Pro IIc
*Orion Starshoot DSCI
*CG5 mount
http://cleardarksky.com/c/AlbuqNMkey.html

My Messier Project Gallery


Post Extras: Print Post   Remind Me!   Notify Moderator  
DaemonGPF
Pooh-Bah
*****

Reged: 03/22/08
Posts: 1428
Loc: New Mexico
Re: More image problems. new [Re: DaemonGPF]
      #2596868 - 08/22/08 03:20 PM

Cheating it a little, I took your file and applied a very light gausian blur and then a light unsharp mask and it cleared most of it up in one pass.



--------------------
-Josh

*Orion Starblast Imaging 150mm OTA
*Orion Starblast Imaging 114mm OTA
*Meade 50mm AR short tube OTA
*Meade DSI Pro IIc
*Orion Starshoot DSCI
*CG5 mount
http://cleardarksky.com/c/AlbuqNMkey.html

My Messier Project Gallery


Post Extras: Print Post   Remind Me!   Notify Moderator  
Nils_Lars
scholastic sledgehammer
*****

Reged: 01/04/08
Posts: 903
Loc: Santa Cruz Mountains , CA
Re: More image problems. new [Re: DaemonGPF]
      #2596915 - 08/22/08 03:43 PM

Im not familiar with that imager but it looks like a high gain or you just need longer subs.

--------------------
Erik

Orion ED 80
Orion Atlas GOTO mount
Williams Optics reducer
Various eyepieces and other gear
Baytronix 80mm guidescope
Orion Starshoot Autoguider
PHD guide
Canon 400D (unmodded)
Stilleto Focuser
Tamron 75-300mm&28-80mm lenses
NexImage webcam

http://home.comcast.net/~eriknlarsen/site/?/photos/


Post Extras: Print Post   Remind Me!   Notify Moderator  
AlanT
sage
*****

Reged: 08/20/07
Posts: 271
Loc: 122º36' W, 47º37' N, WA USA
Re: More image problems. new [Re: Nils_Lars]
      #2597003 - 08/22/08 04:28 PM

I agree there is some banding in there (but pretty dim). I sometimes get that on an occasional frame. You might look through the Light frames and discard any bad ones. But also, it sorta looks to me like the darks may not be right (for the light frames taken).... or maybe they've been subtracted twice?

A couple questions:

1. What software did you use for capture? If you used Envisage, did you have the "Subtract Darks" box checked or not. If so, your "light frames" are already dark subtracted.

2. Were the Darks taken the same night, at the same temperature? The DSI cameras are very sensitive to temperature shift. Just a few degrees F makes a difference.

As a note, your image is presented as if the pixels are square. The pixels on a DSI are 9.6 H x 7.5 V. so when scaled, the normal image aspect ratio will be roughly 4 x 3 rather than the almost square image you have here. The natural image size for a DSI is a just a bit bigger than 640 x 480.

al

--------------------
Meade 80mm APO
Celestron C6
CGE, CG-5 GT
DSI Pro, DSI Pro II, ST-2000xcm


Post Extras: Print Post   Remind Me!   Notify Moderator  
RandallK
professor emeritus


Reged: 11/10/06
Posts: 713
Loc: Nanaimo, B. C. Canada
Re: More image problems. new [Re: AlanT]
      #2597164 - 08/22/08 06:09 PM

You didn't by any chance switch to another "window" while imaging? I did this with my Orion (Original DSCI), while taking darks and it created streaks through them. If I didn't switch windows and let it do it's thing, everything comes out fine. Also, could it maybe be a thermal problem?

--------------------
Scopes: Meade SC-8AT w UHTC
SkyWatcher 5" F/5 Reflector
SkyWatcher 127mm MAK
Mount: HEQ5 Pro
Cameras: Orion Starshoot DS Colour Imager V.1
Imaging Source Webcam DMK21AU04.AS
Palm TX PDA w Astromist and Bluetooth wireles control.


Post Extras: Print Post   Remind Me!   Notify Moderator  
EricJD
super member


Reged: 07/24/07
Posts: 112
Loc: Chesapeake VA
Re: More image problems. new [Re: RandallK]
      #2597170 - 08/22/08 06:13 PM

Well, I guess my problem is my dark then. I didn't take it the same night.

Oh well, time for a do-over. Thanks everyone for the advice.

--------------------
Orion 120mm @ f5


Post Extras: Print Post   Remind Me!   Notify Moderator  
DaemonGPF
Pooh-Bah
*****

Reged: 03/22/08
Posts: 1428
Loc: New Mexico
Re: More image problems. new [Re: EricJD]
      #2597235 - 08/22/08 06:44 PM

Well, the best way to narrow it down would be to look at the exposures without dark subtraction. Are those bands/spots present?

--------------------
-Josh

*Orion Starblast Imaging 150mm OTA
*Orion Starblast Imaging 114mm OTA
*Meade 50mm AR short tube OTA
*Meade DSI Pro IIc
*Orion Starshoot DSCI
*CG5 mount
http://cleardarksky.com/c/AlbuqNMkey.html

My Messier Project Gallery


Post Extras: Print Post   Remind Me!   Notify Moderator  
EricJD
super member


Reged: 07/24/07
Posts: 112
Loc: Chesapeake VA
Re: More image problems. new [Re: DaemonGPF]
      #2597360 - 08/22/08 07:57 PM

Yes, they are.

--------------------
Orion 120mm @ f5


Post Extras: Print Post   Remind Me!   Notify Moderator  
AlanT
sage
*****

Reged: 08/20/07
Posts: 271
Loc: 122º36' W, 47º37' N, WA USA
Re: More image problems. [Re: EricJD]
      #2597378 - 08/22/08 08:06 PM

Are the bands on all or just some of the frames? If on all the frames I'd be suspicious of the USB hookup (cable, hub, etc.), or maybe the capture software.

What software, and what exposure time?

al

--------------------
Meade 80mm APO
Celestron C6
CGE, CG-5 GT
DSI Pro, DSI Pro II, ST-2000xcm


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1


Extra information
5 registered and 4 anonymous users are browsing this forum.

Moderator:  Charlie Hein, knuklhdastnmr 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 173

Jump to

Home



Cloudy Nights Sponsor: Astronomics