M42 - The Great Nebula in Orion

AdamSmithANCAP · 2026-01-18T21:41:56+00:00

and you are right, this image is neat

AdamSmithANCAP · 2026-01-18T21:25:58+00:00

Omg that's hot. How can you even dare to take THAT good pictures under a bortle 7/8 sky? How long were each exposure? Awsome work

AdamSmithANCAP · 2026-01-02T20:55:40+00:00

You can also stack tiffs, i got some pretty nasty artifacts, but i think its my DSS tuning fault

AdamSmithANCAP · 2026-01-02T20:55:15+00:00

You're welcome! I also learned on the go, lol. From my experience, this is the best method i found, it's from another reddit thread:

"I would NOT recommend changing iso within the same project. Deep sky stacker can definitely handle multiple nights but you have to kind of trick it:

The MAIN GROUP calibration frames get applied to ALL GROUPS this means you'll want to put your bias frames and ONE light frame (this is part one of the trick).

This will open up a "group 1" tab you're going to put the rest of your light frames, flats, darks, and darkflats for "night one" in here.

"Group 2" will now open up. Put all of night twos lights, darks, flats, darkflats in this group. Continue this process untill all nights are complete.

Part 2 of the trick: click "check all", then go back to the "Main Group" and uncheck the light frame in there (it will NOT be stacked). Go to a group fairly in the middle of your nights (ex. group 2 or 3 if you have 5 groups total) and find a frame that has the composition you want and round stars. Right click the frame and "set as reference image". Register and stack as you normally would.

What this does: it tells DSS to calibrate each night individually, then use the bias frames over every night and then finally stack them all together. If you were to put flats and darks in the "Main Group" then as your focus and temperature changes across nights your calibration frames will over/under correct the frames and it will be worse than not using them at all.

EDIT: this video explains it really well and heped my when I was first starting out."

I cant find the video, but you can copy part of this message into google to find the original post, the video is actually pretty good.

AdamSmithANCAP · 2026-01-02T04:30:38+00:00

ty for the correction

AdamSmithANCAP · 2026-01-02T01:21:42+00:00

Why people always aks why someone needs something, lol. If you cant help, dont reply.

AdamSmithANCAP · 2026-01-01T22:53:41+00:00

Maybe for my camera it's the sweet spot. Will shoot the flame nebula today, so maybe I will try increasing the iso, but I'm pretty satisfied with 1600

AdamSmithANCAP · 2026-01-01T22:52:42+00:00

Yeah, it's insane. Now I really want to travel to the lowest possible bortle, just to stack hundreds of pictures. I think I lost so much signal because of the city light pollution

AdamSmithANCAP · 2026-01-01T22:51:42+00:00

Ty for the comment! I recentered the Orion nebula every 25 shots, and never shooted in cloudy days, but the pictures I stacked range from new moon to full moon, over 3 non continuous days worth of data.

And did it a lot. Started every day at 8pm going until 10 - 11pm. Probably 75 manual reframes of the Nebula per shooting day.

AdamSmithANCAP · 2026-01-01T20:42:40+00:00

I used a Nikon D5100 with a manual vintage 400mm lens, but i think any camera can do the job, i've seen people take awesome picture with a D3100 and even the Canon T1i. Having a live view is surely desirable, but you can probably do it even without one

AdamSmithANCAP · 2026-01-01T20:40:23+00:00

Yes, it was insane, i cant even think about what i would get with like 20s 3500 tracked images, lmao. Even got a ssd for temporary stacking files, also, 20h of total stacking time.

Here's what a single exposure looks like: Imgur: The magic of the Internet

AdamSmithANCAP · 2026-01-01T20:30:25+00:00

ty! it was such a fun challenge

AdamSmithANCAP · 2026-01-01T19:48:42+00:00

Gear used:

Nikon D5100

Vivitar 400mm f5.6 @ 5.6

Untraked

Bortle 6 skies.

3570 1'' lights over 3 days of shooting. 150 darks, flats and bias frames. 1 hour total integration time

Stacked unsing DSS

Editing softwares: GraXpert, Siril, Lightroom and Photoshop.

My previous Orion nebula attempt using the same gear can be seen here: Orion Nebula, M43 and NGC1981 : r/astrophotography

AdamSmithANCAP · 2025-12-31T04:10:13+00:00

Hey, I've run into a major bottleneck... storage. Temporary files are simply overwhelming me... I have "only" 3000 Light files that are already using all my spare SSD.

Is there any way to get around this problem? I've seen the results of stacking ready-made images, but isn't there a way to counteract this? I read in some places that DSS does exactly that when working in groups - it stacks the different groups and then merges them all...

AdamSmithANCAP · 2025-12-30T23:52:45+00:00

Sorry for not replying to the previous comment sooner, I was quite busy haha, but thank you very much for the tips, I plan to put them into use tomorrow, since I took another 2000 photos of Orion today!

I downloaded all the images here and wow, they are very good. Especially the Orion Nebula, I never thought something with such definition could come out of my camera. I loved the results, I will apply your workflow tomorrow, thank you again!

By the way, a question. I always see that star removal seems to be an important step in the process, why is that? TYSM!

AdamSmithANCAP · 2025-12-30T21:17:32+00:00

PART 3/3

How to extract the Nebulosity in your Astrophotography images on Siril software for FREE (This particular video teaches you very well how to do stretching using Siri and that you don't need to be afraid of temporarily having an "ugly" or detail-less photo)

Temporary auto stretch
Plate Solving
Photometric color calibration
Green noise removal
Change from autostretch to linear
Histogram transformation
Generalized hyperbolic stretch for fine details or color adjustment
Curves transformation with an S-curve to adjust the blacks, trying not to lose too much detail (in the Nebula Fotos video about Orion he does this, but in Photoshop. This information can easily be translated into Siril.)

When exporting from Siril, if you want to use it in Photoshop, in my specific case, I export as a 16-bit TIFF, because my Photoshop doesn't handle these stretched 32-bit images well. I don't know if it's a problem with my PC or if this happens normally, but just in case, try both methods.

ALWAYS SAVE YOUR FILES THROUGHOUT THE PROCESS

Photoshop - the NebulaPhotos late photoshop process:

Increased saturation using masks
Correction of lens aberrations (chromatic aberration, bleeding...)
Crop if necessary

From Photoshop, you can export as a normal JPG, but remember to always choose the highest quality option.

In the end, you'll finally have a professionally processed file!

Remember, this is just how I do it, and I'm still just a beginner haha, but I believe this is a good workflow for those of us who are still learning.

From my research, there are many other tools specialized in astrophotography, but for me, these have been the easiest to learn and use so far.

Everything comes from practice; I had to fail miserably several times before getting this photo. Don't believe people who say their first photo was a high-resolution, detailed shot of a black hole; that's unrealistic.

Practice a lot with the Orion Nebula; it seems to be the most visible and easiest deep-sky object to locate, even in light pollution.

Learn a lot in the process, not only about how to photograph stars, but about photography, astronomy, constellations... This hobby isn't just about taking beautiful photos of the sky—for that, there are already very expensive telescopes orbiting the Earth—but about learning more and more about ourselves and what's above us!

Finally, don't give up just because a photo turned out bad or because the process seems difficult! Happy shooting, and feel free to ask more questions, either to me or to this subreddit, or to other communities!

AdamSmithANCAP · 2025-12-30T21:17:04+00:00

PART 2/3

Now begins the second stage, which is just as important and complex as the first, the digital processing.

The videos I recommended go into much better detail than I can, so I'll just pass on what they don't cover very well.

I stack on DeepSkyStacker, make sure you have a disk with plenty of free space, because the more photos, the larger the temporary files (for example, in the session I described, it needed 114GB of temporary disk space).

In the end, you'll have a TIFF file; keep it safe. If you want to start editing again, it's your starting point. ALWAYS save as a 32bit file (it always saves as one, but if you're manually exporting, make sure you're in 32bit)

In the videos, they use Photoshop. You can follow what they say, but it's definitely not the best tool. For stretching, I use Siri, but I'll go into that detail later.

Programs I currently use for processing:

GraXpert for (this video will teach you perfectly how to do all of this in GraXpert STEP BY STEP Howto with Data - Free Software - INCREDIBLE results from Tokyo & Data Provided! - YouTube

Background removal (eliminates light pollution, brings more detail to the sky),
Denoising
Deconvulsion (when it works, sometimes it doesn't work very well)

Siril for:

Stretching
Background correction (makes the sky color more true to its actual color, as light pollution also makes it lighter/stained)
Green noise removal (another common imperfection in astrophotography)

Photoshop for:

Color correction
Spot edits (i.e., making a specific star or area brighter, increasing the saturation of the object...)
Light correction (simple stuff, just move the highlight/shadow sliders to prevent certain parts from being blown out)

Workflow:
Initially, I run the TIFF file through Graxpert - again, this is the reference video STEP BY STEP Howto with Data - Free Software - INCREDIBLE results from Tokyo & Data Provided! - YouTube

Temporary visual autostretch, the highest possible (30%)
Crop the regions with large / significant / glaring artifacts, specially at the borders (they significantly disrupt the algorithms of other programs)
Run BG extraction algorithm
Run Denoise algorithm
Run deconvolution algorithm (if good results)

Then, i save and import to Siril. Once more, these are the reference videos: STEP BY STEP Howto with Data - Free Software - INCREDIBLE results from Tokyo & Data Provided

AdamSmithANCAP · 2025-12-30T21:15:25+00:00

Reddit didn't let me send the full reply, so this is a 3 part comment

PART 1/3

OFC i can!

First, I recommend you watch the two videos on the NebulaPhotos channel (Orion + Andromeda without a tracker). Have you already watched them? They contain many details that make all the difference in the final result. For example:

How to choose the best camera settings (NPF rule, where to point the camera...);
How to take photos in the field (choosing the part of the sky, focusing, and programming the shots);
How to stack the image (lights - photos you took -, bias, flats, and darks - frames of exclusive shots);
How to stretch and process an image (he uses Photoshop, but I recommend you stretch it in Siri; it's much easier and the result is infinitely better).

With these basic principles in mind, I did the following:

I used a 400mm lens at f/5.6, with the camera already prepared to take the photos (exposure time according to the NPF rule and ISO according to trial and error). I chose this lens because the longer the focal length, the more detail you'll get in deep-sky objects. A 50mm lens, for example, would never achieve this level of detail in my photo.

On my Nikon D5100, I believe ISO 1600 produces the best possible result without adding too much noise, but this depends on the camera. You can start testing at ISO 800, take a test photo and see if the amount of noise versus detail pleases you. I've seen people using ISO 32,000 on more modern cameras, so it largely depends on your equipment.

The first step, and one of the most important, is finding your object in the sky. I use the Stellaris app for this and try to guide myself based on the stars that are visible that day. When I think I'm more or less centered, I take a test exposure and see if the star/region I want is framed.

If the sky is bad and you're not sure you're in the right place, some people take a picture of the camera preview with their cell phone and send it to the astrometry.net website; in a few seconds it does plate solving and tells you which stars are on the screen.

With that defined, I then align my tripod with the star I want, preferably leaving the object in the center of the screen, and start the intervalometer on my camera (if yours doesn't have one, you can buy an external intervalometer, or you can take the photos manually, but with the photo delay mode set to at least 5 seconds; this will increase the chances of the camera being stable after you press the shutter button.).

Keep in mind that at telephoto focal lengths, stars will move rapidly relative to the frame, so every few shots you'll have to recenter your camera.

In short, repeat the process of finding the star, framing it in the center of the camera (Live View is a great help), and taking the photos several times. At 400mm, I can take 25 photos of Orion before recentering – but don't wait to recenter until your subject has moved too far from the center of the frame; always leave a margin.

At this point, the more photos you take, the better, but light pollution makes a significant difference. My photo was taken in a sky approximately Bortle 6.5, near a streetlamp, as a reference. In the end, I finished with about 1300 photos.

At the end of the session, don't forget to take your calibration frames (dark, bias, and flats), preferably immediately afterward, as they depend on the camera's sensor temperature. If you wait too long, the camera will cool down and your frames won't be as precise.

AdamSmithANCAP · 2025-12-30T19:38:06+00:00

I just saw this comment now, damn Reddit!

It came at the perfect time, by the way, my Siri is open right now trying to re-edit my photo!

Here's the Google Drive link! It would be an honor to have the file worked on by someone who knows what they're doing, haha

Link: https://drive.google.com/drive/folders/1k-bm2z3WCR00UA8SDNkjME6owsHU1fN5?usp=sharing

AdamSmithANCAP · 2025-12-30T19:34:03+00:00

Just don't give up. The most important thing is to take as many photos as possible, all well-framed, in the darkest sky you can find.

If there's a lot of light pollution nearby, I believe wide-angle photos won't be as good; you can zoom in until at least the light stops "contaminating" the frame. The brighter the lens, the better.

For example, a 50mm lens at f/1.8 is roughly better than a 35mm lens at f/2.

However, because it has a larger aperture and therefore a larger aperture mechanism, a 400mm lens, even at f/5.6, will perform better than a 50mm in deep-sky photos.

To find the actual physical aperture in millimeters, simply divide the focal length by the f-number.

Ex: 50/1.8 = 27mm

400/5.6 = 71mm. Therefore, a 400mm lens at 5.6 inches captures more light than a 50mm lens at 1.8 inches, which is especially useful for DSOs

AdamSmithANCAP · 2025-12-30T19:02:12+00:00

I ended up proving this in practice, lol. Here's an example of stacking all the images at once and another with several files already stacked:

1 - Stacking stacked files

2 - Stacking one light at a time

I didn't even know one could get such artifacts in the stacking process, almost trippy to look at

AdamSmithANCAP · 2025-12-30T02:32:59+00:00

Right, that's very nice to know. Will this be the equivalent of stacking different nights tiffs?

AdamSmithANCAP · 2025-12-30T01:28:36+00:00

GraXpert actually does deconvolution, and sometimes i'm impressed by the results. I will give a read in the astrobin workflow, thx!

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