19 replies to this topic

[JebTheGreat]

Hi all, I have got a few question that I am wondering about.

 

Question 1:

So recently I started getting into astrophotography and I deiced to capture the Orion nebula with just my Canon EOS 1300D + EF-S 50-250

and a tripod. I took 400 Lights(1 second exposure, ISO 1600) + 50 Darks, 50 Biases and 30 Flats and then stacked it in DeepSkyStacker using the average method.

For some reason it looks really noisy when is Strech the histogram in GIMP, and i just cant get it to look anywhere near this: https://www.youtube....h?v=bDqrW8cLEx8

even though i am using similar equipment. Here is the Stacked TIFF: https://drive.google...?usp=drive_link

 

Question 2: 

What piece of equipment should I buy next, I only have a budget of about $300 dollars

and I know that is very little but what would give me better results than what I am using

(example: star tracker, telescope, astronomy camera, etc.)

[jml79]

It's a little above your budget but I would save the extra pennies and get a ZWO Seestar S50. There is a new smaller S30 coming on the market too. If you don't want to go the smart scope route then a tracker would be my pick but they are very limited in what they can do.

[EPinNC]

The Google drive link asks for a login.

 

That aside, 400 seconds of exposure is only about 6.7 minutes.  Definitely enough to see the Orion Nebula.  This is less than 4 minutes, and I did a very poor job of processing it.  But noise is going to be a problem with such a short total exposure ("integration") time, even with proper calibration frames applied.  (Good on you for doing those!)

 

I don't have experience with trackers.  But I think a tracker or something similar might be the next biggest step to take, though even that might exceed your budget unless you can find a used one.  Although the Star Adventurer Mini looks interesting if you could attach it to your existing tripod.  Someone else here should speak to how well that works.

 

If your camera and lenses are of decent quality, I think the single biggest improvement you can make is to follow the stars as they move for enough time to get individual exposures of 10, 20, 30, or more seconds without star trailing.  As jml79 points out, trackers do have limitations, but budget limitations unfortunately can override all other concerns.  Such is life!

 

Meanwhile, keep doing what you're doing, be patient, and learn all those processing skills that will be useful later

[vio]

Before going into equipment purchase mode, it may help to understand why your experiment did not result in similar results as the one you compare the session to (from the video).

There are 3 possible differences I can think of, one being unclear as you don’t mention it in your description of the setup.

1. Light pollution. You may be comparing your location (unspecified) to the Bortle 6 location used in the video. The difference, if any, could result in a different SNR compared to the one possible in the video.

2. ISO setting. While you used approximately the same total exposure time, you shot at 4 times less ISO than in the video, with less signal captured in your experiment.

3. Image format. You mention stacking TIFFs, while the video mentions using RAW format. That said, I’m not familiar with the possibilities of the two Canon cameras to know if this could affect the result, just mentioning it as a possible difference.

I am not suggesting that your next purchase would not result in better quality and easier image capture, just highlighting possible cause to explaining differences in final results.

There is another difference, which in astrophotography is at least half the battle - processing. Trying to match results, even with the same frames captured, is harder than it may seem.


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[JebTheGreat]

sorry I forget to share the files publicly(stupid me)

but I updated it so you can check now

also thanks so much for the advice

[JebTheGreat]

1. yep I checked on the light pollution map and i am a Bortle 6

2. I tried 6400 ISO in the beginning but it still gave very noisy results

3. i did stack using RAW's but the output was TIFF

 

Thanks for the help though

[rj144]

Don't use GIMP for stretching.  Learn how to use Siril.

[rj144]

1. yep I checked on the light pollution map and i am a Bortle 6

2. I tried 6400 ISO in the beginning but it still gave very noisy results

3. i did stack using RAW's but the output was TIFF

 

Thanks for the help though

Look up the optimum ISO for astro for your camera and leave it at that.  Raising ISO does not capture more photons.

[JebTheGreat]

Look up the optimum ISO for astro for your camera and leave it at that.  Raising ISO does not capture more photons.

just interested what does iso actually do, like why does it increase brightness and increase noise

[rj144]

just interested what does iso actually do, like why does it increase brightness and increase noise

It's a digital gain.  Like turning up the volume on a mic... it doesn't capture more sound, it makes the sound louder.

 

I looked at your pic.  Look into GraXpert and Siril.  It's kind of normal for your setup.  You need more integration time (400 s is nothing really... you need hours) and learn how to process.  You're also a bit out of focus.

Edited by rj144, 06 February 2025 - 09:38 AM.

[JebTheGreat]

Ok thanks, but how come the video I linked got those results

[JebTheGreat]

Also could someone maybe post a processed version of the pic just so I can see

[markalot63]

just interested what does iso actually do, like why does it increase brightness and increase noise

You don't get something for nothing.  Sensors usually have an optimum ISO, I am more familiar with Nikon, but IIRC 1600 ISO is good for most Canon cameras. It's just applying current to the sensor and at some point more current is not good.

 

Every camera has noise, and with super short exposures, even on a bright target, some parts of the image will be just barely above the noise floor.   Stacking images is the attempt to bring detail above the noise, but its integration time and quality of each sub that matters. 

 

This is 7.6 total minutes of 20 second subs in a Bortle 6 zone.  Cooled camera and guided, so each sub has a greater signal to noise ratio because of camera and sub length.  Had I used 1 second subs I would almost certainly need more integration time.  

 

[JebTheGreat]

wow that is a great photo!

Edited by JebTheGreat, 06 February 2025 - 09:51 AM.

[rj144]

Ok thanks, but how come the video I linked got those results

No offense, but I'm not watching a 30 minute video that's three years to old to tell you.  It's most likely because he did more integration time with less light pollution.

 

By the way, watch more recent videos on astrophotography.  It's advanced like 100 fold in the last 3 years.

[markalot63]

And here is yours, using Siril free, starnet++ free.  Cropped, background extraction, removed stars, quick and dirty stretch, some color increase, recomposed stars.  The data is NOT horrible, and with more time and skill someone can do a better job at editing.

 

Edited by markalot63, 06 February 2025 - 10:31 AM.

[EPinNC]

Also could someone maybe post a processed version of the pic just so I can see

A quick effort using Siril for stretching (i.e., brightness/contrast increase), RawTherapee for its noise reduction tools, and GIMP for some tweaks to brightness and saturation:

 

 

It's there!  Someone with better tools and more skill might be able to pull a bit more out of it.  A couple of comments:

 

Yes, the focus does seem a little soft.  Focusing with a DSLR can be difficult, so it's just something to work on.  The problem may just be technique, or it could be your lens. Some zoom lenses are not exactly the best -- they are compromises for usage in terrestrial photography and they can have sharpness and distortion issues.

 

The background shows a rounded "vignetting" issue, as if your flats did not properly (or fully) correct for uneven illumination of the sensor.  I was able to compensate for that to some degree with Siril's "background extraction" tool.  But don't feel bad... I have had a devil of a time getting good flats with camera lenses.  Either I'm doing something wrong or there is just some inherent difficulty in doing that.

 

But really, for your effort this is a pretty nice result.  Look at that fantastic thing you captured!  One of the more wondrous sights in the night sky, and you have your very own picture of it, well beyond what the human eye could see.  Always remember that, no matter how happy you are with the technical aspects of your images.  Getting pictures like this is a tremendously difficult thing to do, and you've done it.

[JebTheGreat]

Wow thats really incredible guys thanks you so much

[IDoStupidThings]

When I first started out, I built a barn door tracker and it worked relatively well. https://garyseronik....trophotography/

 

They're cheap and easy to build, and will allow you to take longer exposures. With a bit of practice, I was able to take 30" subs at 70mm with my APS-C DSLR. 

 

If you want to spend the money, something like a Star Adventurer will help a lot, but they can be expensive for a newcomer. 

[starslicer]

You could try like 5 second subs.

 

The first image I ever took was with an old Meade refractor from the 90s and an ASI 120MC-S camera that was pretty obviously built for taking pictures of planets. Subs were 5 seconds over an hour of integration unguided but I think the mount was tracking. I guess the point is, you need more total integration to get rid of that noise. I also don't know anything about your cameras gain/ISO but having it too high will not help you at all. You can't really cheat these images at the moment. There is probably a sweet spot ISO setting for that camera.

 

I'd get an hour at least total. Orion is bright so you have that going for you.

 

Hah, I found the old thread too. Poor Idclimber was trying to help my sorry butt.

 

https://www.cloudyni...ucer-questions/