Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

ASi 071 pro darks

  • Please log in to reply
9 replies to this topic

#1 Christian-UAE

Christian-UAE

    Vostok 1

  • -----
  • topic starter
  • Posts: 168
  • Joined: 04 Jan 2017
  • Loc: Abu Dhabi

Posted 11 March 2019 - 11:22 AM

Hello,

 

I have recieved a new ASI071 today and I am in the process to create my darl libarray.

 

Can you please let me know if this masterdark (40 x 60 sec, Gain 0, -5 degree Celsius, integrated in pixinsight) looks normal for this camera ? I do see patterns and banding and a lot of glow.  The darks I do with my ASI1600 are much more cleaner....

 

I would appreciate if a ASI071 owner could post a masterdark from his library to compare.

 

Thank you very much

 

Christian

Attached Thumbnails

  • dark 60 sec.jpg


#2 descott12

descott12

    Viking 1

  • -----
  • Posts: 878
  • Joined: 28 Sep 2018
  • Loc: Charlotte, NC

Posted 11 March 2019 - 05:50 PM

I am pretty new to this stuff so this may be way off but that looks like a flat frame, not a dark...



#3 Christian-UAE

Christian-UAE

    Vostok 1

  • -----
  • topic starter
  • Posts: 168
  • Joined: 04 Jan 2017
  • Loc: Abu Dhabi

Posted 11 March 2019 - 09:32 PM

Hi.
It's a heavy stretched Masterdark.
Regards
Christian

#4 John Miele

John Miele

    Gemini

  • *****
  • Posts: 3363
  • Joined: 29 May 2005
  • Loc: North Alabama

Posted 12 March 2019 - 05:35 PM

Here is one from my ASI071 pro. This is a master dark consisting of 25x60 seconds. Taken at -5 deg.C at unity gain. Sorry I do not have any at zero gain.

 

The first image is the full field. The second image is a center crop. You can see my dark pixels in the center crop. I don't seem to have as much of the vertical banding but there is some there for sure. These are both very heavily stretched...John

Attached Thumbnails

  • dark-full.jpg


#5 John Miele

John Miele

    Gemini

  • *****
  • Posts: 3363
  • Joined: 29 May 2005
  • Loc: North Alabama

Posted 12 March 2019 - 05:36 PM

Now here is a center full scale crop...

 

And I'll add when you stretch this hard, I'm not sure it tells you much as so much weird junk seems to appear. The real test is do the darks work...do they help your images? My darks always help so I think they are doing their job. 

Attached Thumbnails

  • dark-crop.jpg

Edited by John Miele, 12 March 2019 - 05:40 PM.


#6 Christian-UAE

Christian-UAE

    Vostok 1

  • -----
  • topic starter
  • Posts: 168
  • Joined: 04 Jan 2017
  • Loc: Abu Dhabi

Posted 13 March 2019 - 09:22 PM

John.
Thank you very much for your reply. I will try my darks during processing and I will see how they will work.

Regards
Christian

#7 jgraham

jgraham

    ISS

  • *****
  • Posts: 20125
  • Joined: 02 Dec 2004
  • Loc: Miami Valley Astronomical Society

Posted 14 March 2019 - 10:59 AM

Pretty much standard fare for all of my cameras including my ASI071MC Pro. Darks do a great job cleaning things up. Any residual is usually from scrum flowing across the field.

#8 AhBok

AhBok

    Vanguard

  • *****
  • Posts: 2216
  • Joined: 02 Dec 2010
  • Loc: Lakeland, TN

Posted 14 March 2019 - 03:34 PM

Are you taking your darks during the day with just a plastic cover over the scope end? I find I must use the cover plus a thick black felt piece of material draped over that to prevent light leakage when taking darks in a lit room. I even cover the bottom of my newt and turn the lights off to get the best flats with my ASI071MC Pro. I mostly use unity gain and 120-300 sec exposures.

#9 Jon Rista

Jon Rista

    ISS

  • *****
  • Posts: 23352
  • Joined: 10 Jan 2014
  • Loc: Colorado

Posted 14 March 2019 - 06:19 PM

You are seeing FPN, fixed pattern noise. DFPN, dark fixed patter noise in this case, to be exact. DFPN is THE reason we create master darks and calibrate with them in the first place. Without DFPN, there really is no need for a master dark...no DFPN means the dark is a perfectly flat offset, and if that were the case, removing the offset would simply require a subtraction. 

 

Every camera has DFPN, to one degree or another. It's totally normal. In fact, if your master dark was not modeling this FPN accurately, then subtracting it from each light would be an ineffective means of correcting this pattern in the lights. So, what you are seeing is not only normal, but expected and desired. 



#10 Christian-UAE

Christian-UAE

    Vostok 1

  • -----
  • topic starter
  • Posts: 168
  • Joined: 04 Jan 2017
  • Loc: Abu Dhabi

Posted 15 March 2019 - 01:48 PM

Thank you all for your replies.

As soon as the much desired and needed rain and cloudy weather stops I will do some test images.

Regards
Christian


CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics