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

Your opinion (Sadr region) of this single sub

  • Please log in to reply
3 replies to this topic

#1 unimatrix0

unimatrix0

    Ranger 4

  • -----
  • topic starter
  • Posts: 341
  • Joined: 03 Jan 2021

Posted 09 May 2021 - 05:29 PM

So, last night around 1am I aimed at nearby the Sadr region and went by the book. 

I turned on Sharpcap and did a sky analysis. 
Sharpcap recommended me to use 270 seconds at 0 gain and offset 5 for max dynamic range and 10% read noise limit.   
Since I don't like that low offset, I went with offset 50 as the default I use. 

I was planning to do maybe 5-6 hours on this target over multiple nights, but now I have my doubts. 

Now, I don't like where this was going, I don't like these subs. I don't like this settings either. 

I have 30 of these, but I don't want to continue doing this, because I think these stars are bloated and a quick stack shows me the final product gonna look like a tomato soup with too much posterization and bloated stars. 

ASI533 MC pro + Astronomik 1.25" UV/IR cut filter

Sesto senso 2 focuser (auto focusing was done 2x during session) 

PHD 2 guiding (guiding is excellent, no issues) with every 2nd frame dithered. 

SVBONY SV503 80ED F7  (yes this scope isn't top of the line, but so far so good, although I'm switching back to W.O.Z61 to get bit wider field)

I'm at Bortle 5. 

 

These are screenshots via snipping tool, I can also upload a single .fits file somewhere if anyone wants a better look. 

 

 

If someone has an idea what I should do here...
Lower the exposure time? 

Raise the gain? 
Is it offset ruining it? 

The other option I had was to do 45 seconds with gain100.  I have done so many of those before, and it's the same problem. I get bloated stars and the subs look over exposed.

Regardless if Sharpcap telling me, this is the best I could do for maximum dynamic range. 

Is this from light pollution? Should I use a light pollution filter instead of an IR-cut filter? 

To me, it's not light pollution, but  the stars that are bloated. Right? 

Or is this supposed to be fine? 

Should I just throw away this scope and go watch a movie on Netflix? lol.gif

 

 

This is what it looks like unstretched and the histogram with ZWO's ASI studio fitsview

Attached Thumbnails

  • unstretchedsub.JPG

Edited by unimatrix0, 09 May 2021 - 05:51 PM.


#2 unimatrix0

unimatrix0

    Ranger 4

  • -----
  • topic starter
  • Posts: 341
  • Joined: 03 Jan 2021

Posted 09 May 2021 - 05:30 PM

I stretched it manually using the histogram slider. This is what's in it

 

I think it's over exposed, if you ask me. 
 

Attached Thumbnails

  • manualstretched.JPG


#3 wizbang396

wizbang396

    Vostok 1

  • ****-
  • Posts: 191
  • Joined: 02 May 2016

Posted 09 May 2021 - 07:42 PM

Try using CURVES, that will adjust the star problem.



#4 unimatrix0

unimatrix0

    Ranger 4

  • -----
  • topic starter
  • Posts: 341
  • Joined: 03 Jan 2021

Posted 09 May 2021 - 08:19 PM

Try using CURVES, that will adjust the star problem.

That would something I would do with the final stacked image. But this is only one sub and I don't want to keep taking them if my subs are bad from the start. 




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