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M86 and friends captured in heavy light pollution

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#1 joelin

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Posted 23 June 2018 - 02:15 AM

Using hyperstar on the C8 with LRGB filters , I managed to capture the area around M86 in very heavy light pollution (this was from West San Jose, CA).

 

I had 130 frames, 70 x 15 sec L, 20 x 15 sec RGB 

 

 

I tried many solutions for tackling the light pollution gradient with many not working. 

 

Here was an intermediate step after doing a basic stretch:

 

V4tOVlx.jpg

 

Pixinsight's ABE/DBE left the image in far worse shape than it started.

YKnrC7o.jpg

 

I tried this method for removing light pollution using levels and the eyedropper  https://www.skyandte...n-astro-images/ but it didn't evenly remove it because of the strong central glow.

 

I therefore tried this method: http://www.ericteske...-from-star.html which uses a gaussian blur and does a subtraction and it did relatively better

 

Some additional cropping resulted this:

nXonayd.png

 

This is the astrobin link where you can see a larger resolution: https://www.astrobin.com/352546/

 

Comments or other suggestions for tackling such strong light pollution welcome.

 

Also, why was my original image so tilted towards the red? The filters were from Optolong and are LRGB.


Edited by joelin, 23 June 2018 - 02:17 AM.

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#2 pfile

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Posted 23 June 2018 - 04:28 PM

is there a reason that you didn't use flats? i would start there... lots of dust donuts and vignetting going on which is compounded with the LP...

 

rob


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#3 joelin

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Posted 23 June 2018 - 10:26 PM

I was being lazy...It's a lot of effort to do flats for L, R, G and B...

 

Maybe I should get a OSC.



#4 Vassar1978

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Posted 24 June 2018 - 03:52 AM

Most capture software can help automate flat acquisition so "being lazy" is not a problem :) !   Example:  SGP has a flats calibration wizard.  Set your scope up with the flats light source (e.g. tee-shirt for sky flats or a light panel).  Run the wizard and it will figure out the exposure lengths you need.  Then use SGP's flats wizard to create a sequence and run it.  Sit back and let your computer do the work, and you've got your flats.  It will take less time than what you're spending trying to process your images to remove the dust donuts and vignetting.

 

Clear skies,

Rowland



#5 pfile

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Posted 24 June 2018 - 03:12 PM

yes i agree, i use SGP and that's what i do. i bought one of those cheap tracing panels on amazon and built an arduino controller for it (the instructions and code are out there...). sgp can control the brightness of the panel that way. takes a couple hours to burn thru a set of flats for all 7 filters.

 

rob



#6 joelin

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Posted 24 June 2018 - 07:11 PM

Well another problem is it’s a pain to switch filters for Hyperstar. That’s why I got lazy...

#7 pfile

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Posted 24 June 2018 - 10:03 PM

ah right, i knew there had to be something like that. i wonder if sjaa has any loaner OSC cameras that are small enough to fit so you can give it a try without committing to anything.

 

rob



#8 Mert

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Posted 25 June 2018 - 12:08 PM

You could try the vignetting tool in APP, maybe that works??

If you like, share the first image or the unstretched image

and I will give it a try!

Regards,

Mert



#9 PhysicsStudent

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Posted 25 June 2018 - 12:29 PM

+1 to the SGP Flats Calibration Wizard. I've used it a few times, as I've tried to find the best method for me to take flats, and it couldn't be easier. As far as getting lazy (I understand this, as I hate taking them), you are most likely never going to be satisfied with your image quality without taking flats. If that isn't something that you want to do with filters, maybe OSC is the way to go. That way you only have to do it once per session.



#10 joelin

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Posted 25 June 2018 - 12:39 PM

You could try the vignetting tool in APP, maybe that works??

If you like, share the first image or the unstretched image

and I will give it a try!

Regards,

Mert

I'll send you something later! Thanks I look forward to hearing the results. 



#11 Mert

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Posted 06 July 2018 - 08:22 AM

I tried a couple of things but the seperate frames do not match

in pixel size, seems like DSS has done it's magic???

R 4649 x 3509

G 4650 x 3508

B 4650 x 3506

L 4644 x 3498

 

What happened here?

 

For example the Red frame, applied ABE and shows quit normal

( here as an example with STF applied )

 

Attached Thumbnails

  • Galaxies_R_ABE.jpg


#12 joelin

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Posted 06 July 2018 - 12:22 PM

I tried a couple of things but the seperate frames do not match

in pixel size, seems like DSS has done it's magic???

R 4649 x 3509

G 4650 x 3508

B 4650 x 3506

L 4644 x 3498

 

What happened here?

 

For example the Red frame, applied ABE and shows quit normal

( here as an example with STF applied )

I don't understand either. Maybe these were the star aligned frames that came out of PI which explains why they're truncated.

 

Or it could be that DSS did something. 

 

Is that a problem with regards to integrating them together?



#13 Bigdan

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Posted 07 July 2018 - 08:54 AM

You need to do the flats.  I'm in Hyperstar mode now, and a dew shield can really make doing them a lot easier.  I can still reach the filter slider with the dew shield installed.  The dew shield allows me to put white T-shirt over the end of the dew shield, and I've got T-shirts stretched over a knitting hoop..... it is super easy to place the hoop over and remove from the end of the dew shield.




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