What is wrong with this image?

[rojach78]

Hi all,

I have been imaging recently without issue but i'm very new to this, i went for the Markarians chain last night but it seems to have issues all around the image?, I'm not sure whether it's light pollution or poor Darks/Flats. 

I used a UV/IR Filter. Any help would be great just so i can find out what it is to make sure it doesn't happen again as this was a total of 4 hours imaging! Thanks.

1.TIF

[Astro Noodles]

Hi 

What kit were you using? Also, what time were these subs take?

What do you think is wrong with the image?

[rojach78]

4 minutes ago, Astro Noodles said:

Hi 

What kit were you using? Also, what time were these subs take?

What do you think is wrong with the image?

I was using Skywatcher evostar 80ED, an ASI553MC Pro for imaging and a HEQ5 Mount. The subs were taken from 11pm to 3am this morning. After stretching the image i see blue stars all around the the outside of the image and i can't balance the colour with the centre of the image

[Cornelius Varley]

@rojach78 Please upload the image as either a jpg or png file so that it can be displayed in the browser.

[rickwayne]

First guess, not having seen the image yet: Did you use flats?

[rojach78]

5 minutes ago, Cornelius Varley said:

@rojach78 Please upload the image as either a jpg or png file so that it can be displayed in the browser.

Hi, I just did a quick stretch to show the issue

[rojach78]

3 minutes ago, rickwayne said:

First guess, not having seen the image yet: Did you use flats?

Yes, i even re-did them but it may be that i'm doing them wrong?

[Snoani]

To be honest it doesn't look too bad.  

Using your TIF I have given it a very quick stretch and removed the green caused by the colour camera. 

There are some gradients which I have quickly removed using AstroFlat Pro but these don't look terrible.  Probably light pollution in your area.  

Otherwise the data looks ok to me.  

[ollypenrice]

Gradient removal does need the right software tools. I think the top dog is still Dynamic Background Extraction in Pixinsight but there are others. AstroArt is pretty good. The previous post shows that the data are workable.

Olly

[rojach78]

19 minutes ago, Snoani said:

To be honest it doesn't look too bad.  

Using your TIF I have given it a very quick stretch and removed the green caused by the colour camera. 

There are some gradients which I have quickly removed using AstroFlat Pro but these don't look terrible.  Probably light pollution in your area.  

Otherwise the data looks ok to me.  

I just don't understand why it hasn't been this bad before? very impressed with your processing though, is there some software i can use in PS to remove the gradient to that level?

 

[iapa]

I just downloaded a copy and stretched a little with Photoshop Mobile. Results seem OK.

More detail came out easily but I’m hardly competent to just someone else’s processing.

If you can post the master dark and master flat someone may be able to identify if there is an issue with them.

You may also want to add dark flats (or flat darks, terminology seems flexible), and bias frames.

What did you stack with?

Edited May 2, 2021 by iapa

[Snoani]

58 minutes ago, rojach78 said:

I just don't understand why it hasn't been this bad before? very impressed with your processing though, is there some software i can use in PS to remove the gradient to that level?

 

It can depend on many factors but what the skies around your location are like is going to be a factor.

Markarian's Chain is very much due south in the early night sky at the moment I would hazard a guess that you have some light pollution in your southern skies.  I may be way off but the fact that you have gradients all around the image may be that your mount flipped as it passed the meridian, meaning that you were initially collecting light pollution on one side of the camera and then the other after the flip.  From my location I have a similar problem to my north.  

There are plugins that you can buy of PS to remove gradients and there is a lot of information out there about people's preferences.  I believe that you can request trial periods for Gradient Xterminator and AstroFlat Pro.  

You can remove gradients in PS manually, which I have done with varying degrees of success.  There is a guide here https://astrobackyard.com/remove-gradients-photoshop/.

 

Edited May 2, 2021 by Snoani

[rojach78]

2 hours ago, Snoani said:

It can depend on many factors but what the skies around your location are like is going to be a factor.

Markarian's Chain is very much due south in the early night sky at the moment I would hazard a guess that you have some light pollution in your southern skies.  I may be way off but the fact that you have gradients all around the image may be that your mount flipped as it passed the meridian, meaning that you were initially collecting light pollution on one side of the camera and then the other after the flip.  From my location I have a similar problem to my north.  

There are plugins that you can buy of PS to remove gradients and there is a lot of information out there about people's preferences.  I believe that you can request trial periods for Gradient Xterminator and AstroFlat Pro.  

You can remove gradients in PS manually, which I have done with varying degrees of success.  There is a guide here https://astrobackyard.com/remove-gradients-photoshop/.

 

I also thought it was light pollution but as I started imaging after the flip I couldn't work out why it was all around the image, I will trial one of the gradient removers for ps, looks like the way to go. Thanks. 

[alacant]

12 hours ago, rojach78 said:

i even re-did them

Hi

The flat frames aren't correcting the field and this is making it more difficult than necessary to process. Perhaps start by cleaning the optical train. I'd pay particular attention to the sensor.

If the uneven field isn't due to light pollution, then I'd say get the flat frames correct and you're good to go. A flat led panel may help you with the lighting for the flat frames. 

There may also be a rogue frame which is misaligned. 

Cheers

[rojach78]

5 hours ago, alacant said:

Hi

The flat frames aren't correcting the field and this is making it more difficult than necessary to process. Perhaps start by cleaning the optical train. I'd pay particular attention to the sensor.

If the uneven field isn't due to light pollution, then I'd say get the flat frames correct and you're good to go. A flat led panel may help you with the lighting for the flat frames. 

There may also be a rogue frame which is misaligned. 

Cheers

Thanks!, love the image. I use Sharpcap and a T shirt for flats with an ipad for the white screen, maybe i need to change this? i'll look into better ways to do my flats

[alacant]

7 minutes ago, rojach78 said:

maybe i need to change this

Dunno. Maybe post -links to- fits originals of a light, a dark and a flat file.

Cheers

[rickwayne]

Gonna put in a plug here for dedicated astro processing software. In the not-very-long run I suspect you will spend less time and encounter less frustration if you use a soup-to-nuts tool such as PixInsight, Astro Pixel Processor, or even SiRiL.  I use APP and the gradient removal and background calibration tools work incredibly well and are super-easy to use. Both programs have generous free-trial periods; APP is famous for balancing ease of use with its excellent feature set, PixInsight is still peerless for its features and power but is famously hard to master.

[michael8554]

For English speakers:

"Soup to nuts" is an American English idiom that conveys the meaning of "from beginning to end", derived from the description of a full course dinner.

😆   😆

Michael