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Pff my M31 sucks..

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#1 F.Meiresonne

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Posted 16 September 2020 - 05:59 AM

M31...

 

70 subs of 60 sec , 400 iso 76 mm EDPH scope F/4.5, FF/FR,guided

50 flats and 50 bias

 

I could not get the color right,not even a bit...winded up with green, or i can get it to blue but not white yelowish  i would prefer...

There is detail allright, although my goal was to get at least 100 minutes of integration, but due to camera issues this failed.

Also a gradiënt, trying to handel it with siril , well it got worse, so i don't think i did it well. Still so much to learn and test...gosh

 

Could not connect with APT, at first camera even died, so i though it was the batterie ,which if forget to charge after taking 150 flats. This was partly true but after 45 min of charging it was allready full so ,...

 

I did not solve the problem, APT connected allright started the job, counted , but nothing happened...lost allready a hour, until i released the SD card and putted it back and.....problem solved...it started to work.

 

First guide test with CEM60 on ST-4, RMS peaking to 1.06, lowest about .59 during the session. I kept an eye on it...

 

all by it a busy session....result questionable...

 

Remarks and suggestios surely welcome.

Attached Thumbnails

  • M31_1 (Large).jpg

Edited by F.Meiresonne, 16 September 2020 - 08:57 AM.

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#2 DubbelDerp

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Posted 16 September 2020 - 07:22 AM

Freddy, if you want to upload your stack, I can try to remove the gradient from it and send it back. I think you have a nice image hiding in there...


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#3 Readerp

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Posted 16 September 2020 - 07:29 AM

Freddy,

 

Welcome to the growing pains of astrophotography :)

 

Don't be discouraged, you are doing many things right, and once you solve these little challenges,

there will be great things ahead!

 

-Pete


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#4 BQ Octantis

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Posted 16 September 2020 - 07:43 AM

Freddy, if you want to upload your stack, I can try to remove the gradient from it and send it back. I think you have a nice image hiding in there...

+1

 

Your stars are clearly round (so well-guided), and 70 minutes on M31 at f/4.5 is a good start. So there's very likely some decent data in there. You just need a good color workflow. But finding it starts with an unstretched stack…

 

BQ



#5 Kevin_A

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Posted 16 September 2020 - 07:50 AM

Freddy,

It looks like all the data is there just a tad over processed in post.... and its much better to deal with that afterwards than try to work with bad data from finicky equipment!!!



#6 Teddythefinger

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Posted 16 September 2020 - 08:21 AM

Don't get down on yourself, There's a ton of people here who will happily help you out. It def takes time! I'm no where close to taking amazing photos like some....but I'm getting there!

#7 F.Meiresonne

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Posted 16 September 2020 - 08:32 AM

Freddy,

It looks like all the data is there just a tad over processed in post.... and its much better to deal with that afterwards than try to work with bad data from finicky equipment!!!

yes , actually I had the same impression. Data is most likely there

 

guess taking the pictures goes rather well lately..only the processing still sucks,

 

I will try to post my 16 bit stack tonight...


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#8 F.Meiresonne

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Posted 16 September 2020 - 08:37 AM

Freddy, if you want to upload your stack, I can try to remove the gradient from it and send it back. I think you have a nice image hiding in there...

Will try to upload tonight, and will post a link

 

Thanks for your help allready



#9 BrendanC

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Posted 16 September 2020 - 08:53 AM

Just popping up to comment on how great it is that people are so supportive on this forum. :)
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#10 F.Meiresonne

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Posted 16 September 2020 - 11:11 AM

Here is the link

 

https://www.dropbox...._16bit.TIF?dl=0

 

A 16 bit tif file, from DSS , just stacked , not touched

 

I hope it is reachable



#11 DubbelDerp

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Posted 16 September 2020 - 11:47 AM

Freddy, your M31 looks REALLY NICE. Here's a quick run-through with Astro Pixel Processor... crop, remove light pollution, and calibrate star colors.

 

I'll upload the unstretched version and send you a link with the gradient removed so you can process it how you would like. I'm not the best at processing, but if you want more details of what I did here, let me know.

 

This would be far from a finished image, but this would be a great time to bring it into GIMP and do some finishing touches.

 

-Todd

 

Annotation 2020-09-16 124009.jpg


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#12 F.Meiresonne

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Posted 16 September 2020 - 12:15 PM

Dear God, what a difference.

 

Seems that i stretched it a bit too far perhaps and i don't understand where that radient came from. Maybe it was to high enough up..

 

Thanks Todd, much appreciate it.

 

I am  much interesting in your procedure.

 

But how did you manage to get the LP out, you have to stretch first before it becomes really nasty...

 

I also thought i overexposed it so  the center was too bright...picture proves actually not ...

 

It seems a bit proven : i am better in taking the picture then processing them ...smirk.gif


Edited by F.Meiresonne, 16 September 2020 - 12:17 PM.


#13 DubbelDerp

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Posted 16 September 2020 - 12:51 PM

I don't think I could bring a raw stack into a program like PS or GIMP and get a recognizable image, to be honest... I let APP do the heavy lifting. I find that it gets me maybe 75% of the way there, but the last 25% takes some other editing program. But since most astro-specific programs will let you remove light pollution gradients on the unstretched data, and just apply a screen stretch so you can see what you're doing, it is much more effective than trying to do so in a terrestrial editing program.

 

I know at one point you were trying out APP, but not sure if you bought it. Here's how I did the initial cleanup in APP:

 

First step was to just load the image with a moderate screen stretch, which shows up like so:

Annotation 2020-09-16 133841.jpg  

 

Looks like your light pollution shows up in this color. I clicked on "neutralize background" and it normalized the histograms, which helps you to see the data a bit better. Although the data itself has not been modified yet.

Annotation 2020-09-16 133930.jpg

 

Since there are some stacking artifacts around the edges, it usually helps to crop them out before removing light pollution gradients. Tools -> batch modify, select the area you want to crop, and click on "crop ok" like this:

Annotation 2020-09-16 134023.jpg


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#14 DubbelDerp

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Posted 16 September 2020 - 01:02 PM

After that, I brought up the "remove light pollution" tool. This tool basically asks you to select areas of clear background sky in your image, no dust lanes, no nebulosity. I selected a bunch of boxes around the galaxy and clicked "calculate." This many boxes is probably overkill, but I usually start in a corner and work my way throughout the image. It's a big help to increase the screen stretch, so you can really see where the background is.

Annotation 2020-09-16 134203.jpg

 

Here's the image, cropped, with gradients removed:

Annotation 2020-09-16 134338.jpg

 

Once the gradient is removed, you can correct the colors in the image by using the "calibrate star colors" tool. Again, you're selecting an area of just stars, no dust lanes or nebulosity. But since M31 is made of stars... I just left it in the selection. It uses the distribution of main sequence stars to make a reasonable guess as to what the color balance should be. The tool looks complicated, but usually the defaults are fine.

Annotation 2020-09-16 134426.jpg

 

That's pretty much it. At this point, if you save a tiff, the stretched data will be written to a new file, and you can process it however you see fit in another program.


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#15 F.Meiresonne

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Posted 16 September 2020 - 01:43 PM

So a couple a images from 'after processing' in GIMP

 

Looks alot better...

 

I learned here i was on the wrong track....GIMP will not be the tool the use...

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  • M31_1 (Medium).jpg

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#16 F.Meiresonne

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Posted 16 September 2020 - 01:44 PM

And another

 

Quite a difference

 

Gosh

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  • M31_3 (Medium).jpg

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#17 DubbelDerp

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Posted 16 September 2020 - 02:02 PM

Looking good! It appears I didn't quite get rid of all the gradient in the image. I sometimes get a lighter bar across the bottom of the frame like that if I forget to cover the viewfinder. Not sure if that is the case here. But it looks like you were able to bring out some of the details in the outer spiral arms.



#18 F.Meiresonne

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Posted 16 September 2020 - 02:23 PM

Well i have often a dark bar at the bottom i don't know where this comes from..i believe i cropped that in one of the images.

 

The gradiënt i Always have on the right bottom side....if i have. Maybe it wast just the Industrial zone from Ghent area.

 

I could have also been my laptop, probably have 5 lights untill i close the lid (forgot it) and took control via Teamviewer indoors....

Of course they are 'stacked in'



#19 42itous1

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Posted 16 September 2020 - 03:25 PM

m31cnfm.jpg

 

 

 

Here's a quick process in PI


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#20 F.Meiresonne

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Posted 16 September 2020 - 03:33 PM

Also very impressive! Thanks Brad

 

This thread was very educational.

 

As said i have to look in into real astro software, if i wanne move on.....


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#21 limeyx

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Posted 16 September 2020 - 04:55 PM

So a couple a images from 'after processing' in GIMP

 

Looks alot better...

 

I learned here i was on the wrong track....GIMP will not be the tool the use...

Indeed. I had very similar struggles to you and DubbelDerp came to my rescue also !

I am looking at Pixinsight right now and may astro photography tool  -- a bit overwhelming but I am convinced I cannot do this in GIMP



#22 DubbelDerp

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Posted 16 September 2020 - 05:31 PM

Thanks, just trying to pay it forward for all the help I’ve gotten here!

#23 BQ Octantis

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Posted 17 September 2020 - 08:37 AM

Good Lord, Freddy…I would hardly say it "sucks"! Here's a basic color calibration in RawTherapee followed by an all-Photoshop workflow:

 

m31_800x600.jpg

 

My assessment:

 

  • The red and green channels are overdriven. Reduce the slopes of the two curves.
  • There is some significant fixed pattern noise after stretch and gradient/light pollution removal. Some more aggressive dithering is in order.
  • I'm not sure what the big dark band is at the bottom of the image, but I had to lop it off.

 

I can see about an all-GIMP workflow post color calibration if that's where you want to go…

 

BQ


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#24 F.Meiresonne

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Posted 17 September 2020 - 12:02 PM

Wow, indeed stunning!

 

Still have difficulties with the terminologie...you speak off..

 

Thing is i don't know yet really what to do , or even  evaluate what errors are in the picture, like walking noise and how to deal with it..

 

I just guess i have to get some real astro software and start a bit with what Todd did, triy to follow that next time.

 

In my stack of M31 there was alot of LP , if there are no gradients in the stack i can make rather well in GIMP, that is why i choose lately objects that are high up.

 

But in case of M31 i don't have that choice , this time of year, guess industriel zone Ghent did his job....

 

The black band at the bottom i have no explanation either, i see it in many of my pictures, in this case i cropped it away in the above pictures in the thread.

 

But indeed i thought  the stack was rather good, seeing the details in my overexposed and crazy color Original pictures...

Am i probably just better at taking pictures then processing them undecided.gif



#25 F.Meiresonne

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Posted 17 September 2020 - 12:04 PM

But the most crazy thing is , that this is possible with an aperture of 'only' 76' mm...bigshock.gif




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