Help - Don't Know How To Do Post Processing On my Milky Way !!!

[Chuleton08]

Hello Everyone!

I had my second semi successful night of taking photos, and I took 26 photos of 30 sec exposures on my Canon 400d, with a 18-200mm lens @ 50mm. It was at ISO 800, and at f/5. I think I have stacked the photos correctly, and tried Siril and DSS for the stacking. However, the Siril one does not look right. If anyone can have a go, or point me towards somewhere where I can learn, that would be great.

If you have any questions that might help, Please ask.

Stacked Images:

 

Stacking With DSS

Stacking With Old Flat Frames In Siril

Stacking Without Flat Frames In Siril

 

 

[Vroobel]

Hi,

Isn't it easier to place the pictures here instead of in an external cloud storage? 

Edited Tuesday at 13:00 by Vroobel

[Chuleton08]

Sorry, I Didn't Think of that 😅

MilkyWayDSS.TIF SirilWithFlats.fit SirilWithoutFlats.fit

[Vroobel]

I doubt if anyone can open FIT files using a smartphone. Could you please present all the pics as JPG files? 

[Chuleton08]

I can try, But they are just stacked and dont look good. Give me a Sec.

 

[Chuleton08]

Here are the three:

DSS:

 

Siril With Flats:

 

Siril Without Flats:

 

[Chuleton08]

Hope Thats What You Wanted.

[Vroobel]

OK, your pictures aren't stretched. After doing it they look like the following:

 

MilkyWayDSS:

 

SirilWithFlats:

 

SirilWithoutFlats:

 

So, what is your question about them?  

 

[Elp]

One of the most basic forms of astro editing and the one likely to provide the most wow factor is levels editing (also know as histogram, shadows/mids/highlights, you can also do it via curves). An unedited linear astro image is incredibly dark, you'll see this in the image histogram, there'll be little graph data other than a large peak on the LHS of the graph (shadows). So you need to brighten the image, or edit your midtone levels so the overall image brightens up. With a level edit tool open you move the midtone point toward the black, this brightens it up, you'll see the histogram peak move toward the RHS (RHS is highlights) stating your data is getting brighter, so to counteract this midtone change you also being the black point/shadows point up toward the histogram peak, this will darken the darkest points again, but the whole process done once has brought up some of the faint signal whilst returning the dark points back to the bottom. By repeating this a few times and applying each time you increase the brightness of your faint signal (the nice stuff) whilst not overblowing the total image brightness (as you're always readjusting the black point). Take care not to clip any of the histogram data (cut it off the graph completely when doing adjustments, this deletes the data and it can't be recovered later down the editing line).

[ollypenrice]

In astrophotography capture is the easy part. (Not always too easy but when you can do it you can do it.) Next comes stacking and calibrating. Again, a mechanical process which can quickly be learned.

And then there is post processing, which is a huge field and not one which can be covered in a single thread like this. You have to start somewhere and this might be a good place. https://www.firstlightoptics.com/books/dark-art-or-magic-bullet-steve-richards.html

Be aware that You Tube is full of clowns who flounder around throwing sliders this way and that without a clue as to what they are really doing. Get a good eye for what are good and bad images and go to the websites of the good ones. Warren Keller, Rob Gendler, Adam Block etc.

Olly

[Vroobel]

Guys, you made a great job by writing the posts above. But there is written "However, the Siril one does not look right", so I understand that the DSS looks right. I didn't want to answer the question which wasn't asked... 

[happy-kat]

Siril image looks particularly green to me

[Vroobel]

24 minutes ago, happy-kat said:

Siril image looks particularly green to me

While the Siril Without Flats doesn't. 

[Chuleton08]

Hi guys, 

Sorry for not responding. Sorry if I was not being clear, but I was struggling to edit the photos in Gimp, and turn them into a nice photo. I had a go my self, and then got someone else to try, and they did a pretty good job.

 

This is my attempt:

 

This is someones else go:

[Chuleton08]

Thanks Everyone btw, It was all very helpful 

[ollypenrice]

It's odd that the flats have corrected the green imbalance. That isn't their job and they don't normally do that. Are you sure you didn't also apply a background extraction or gradient tool of some kind?

Your attempt is, in my view, the better of the two. In the second one the reds have been killed completely whereas, in yours, the Eagle and Swan show some red Ha signal and you have more star colour. The second one has also stretched the data beyond their limit and raised quite a bit of banding into visibility. All data have their limit and successful processing remains just inside them.

I don't know GIMP but, in Photoshop, you can go to Image-Adjustments-Selective Colour and move the top slider in Reds to the left to lower the cyans in red. This helps Ha signal to stand out.

Olly

Edited Wednesday at 06:05 by ollypenrice
typo

[Chuleton08]

Thanks, I did notice too that mine has the two nebula more visible and red. I think with me understanding more about post editing, I think I could still make a nice photo.

Thanks Olly.

[wimvb]

I downloaded the MilkyWayDSS image, and saw one problem immediately: there are no stars in the lower left and upper right sections of the image. My guess is that your camera lens has distortions to the extent that DSS doesn't recognise the stars. It will then register the subs only on the stars in the middle. This leads to further distortions in the corners, and the blurring of any stars there. If you want to get a better image out of this, you have to make sure that DSS can detect stars over the entire image. I'm not familiar with DSS, but there should be a tolerance adjustment somewhere that you can use to detect stars over a larger area of the image.

Here's my result. A simple workflow in PixInsight, based on MilkyWayDSS.tif

Mostly different stretches, but I also used BXT to reduce the stars, NXT to reduce the noise, and SXT to separate the stars from the background, so I could stretch the background more.

[Chuleton08]

Wow, thats still very good. If you have time, try the Siril one with some old flat frames. I think Siril does a better job at fixing small issues like that.

[Chuleton08]

And you can see the nebulas much clearer 

[Elp]

The Siril with flats was fine, I didn't have the green glow from your file above. In Siril I did:

1. Crop (otherwise background extraction doesn't work as good),

2. Dynamic background extraction with around 12 manual sample points none of which should be placed on the milky way or it's dark dust,

3. Banding reduction, DSLRs are prone to this,

4. Green noise removal, be careful with this as it can kill all the colour, this is what happened when I did it, an alternative is to balance your curves in PS/Gimp/Affinity or whatever which will retain the colour data,

5. Around 5 histogram stretches.

Then export as tiff and bring into your image editor of choice. The remaining was a number of curve edits, shadow/highlight edits, minor contrast edits, selective colour, RGB noise reduction (the images are incredibly noisy, you really need more exposure time (hours) rather than rely on noise reduction tools which the "other person's" image shows use of).

Also the point about distorted edges, you'll get that with a lot of lenses especially zooms, primes are much better corrected as they're designed to work at one focal length (they still distort at edges due to physical shapes of lenses projecting onto a flat plane).

The point about nebula, you can see them but if you really want to see them in better detail the majority you need to image at 100mm+, some 200mm then others are telescope territory (unless you have a fine telephoto at hand). More focal length needs better tracking or even autoguiding.

 

[Chuleton08]

Thanks Elp,

 

I did some of the same things in Siril too. But I was unfortunate, and caught a bit of a tree on lots of my photos, so I had to delete half of them  . Also a short night didn't help.

[Elp]

You captured something which is the important thing. I tested a 24mm AF recently, curious test because I've got no way of focusing it other than my ingenious method of screwing the astro camera in and out. It's amazing what you can capture within 30 minutes in a high LP zone.

[Chuleton08]

No manual focus?

 

[wimvb]

1 hour ago, Chuleton08 said:

If you have time, try the Siril one with some old flat frames.

I’m working on that now. The corners are much better.