Bluesboystig

8 minutes ago, alacant said:

Indeed. However all a filter can do is remove signal, never create it. Do without or isolate the emission with say, a UHC. No need to spend a fortune blocking even more light;)

You can see here that there's quite a bit more to be had from the data you already have. 

HTH

Agree, there is definitely more to extract from that data. However, it's the amount of noise extracted with the signal that bothers me, hence my question really. 

1 hour ago, smashing said:

Yep I had similar things and I remember starting trying to aim for 5 plus hours if I could...the 2600MC blew me away when I got my first sub out of it, totally different animal so don't compare the two too much.

I just checked the price tag of the 2600MC.. my eyes are bleeding now 😔 

Would doing longer exposures improve the situation? In other words, is it super worth investing in an ASIAIR mini and guidescope etc for guiding and extending the subs time? Not sure the GTI can handle more than 2 mins without guiding... 

19 minutes ago, smashing said:

Is your camera modded? Just looking at that and what I managed with a modded camera in just over 2 hours of data and your picture looks great in comparison so well done.

It has also been pretty warm lately which my DSLR hated when I was using it in the warmer months.

I think I also was using longer 4/5 min subs as well but that has its own problems.

I think, if I'm reading it correctly, that tutorial is using a 2600mc pro which yes will have substantially different to your DSLR

No my camera is just the normal unmodded one. Thanks for the praise, maybe my expectations are a bit too high? I know that that longer the total integration time the better, but I thought that 3.5h would give me a better SNR. It required so much stretching to get anything out of the stacked image that it brought out all the noise as well. 

Hi everyone, I have started recently in this incredible hobby and I'm full of questions, like many others I suppose. One thing I have noticed is that my images have an incredible amount of noise and not much data in them. My latest project was the Heart Nebula: on a really good night with no moon, I took 101 subs 2 minutes each at ISO 800 with my Canon eos 2000d and WO z61 with an Optolong L-Pro filter. Very disappointingly there wasn't much in each individual raw file, I can barely see any hint of nebulosity. I was then reading Siril processing tutorial and noticed the picture on top: one single RAW (with the same filter) had way more information in it than my entire stack of 3h and 20 mins! Am I missing something here? I feel like I should be getting more data per sub but I don't really understand what I'm doing wrong. I understand the Heart Nebula is an emission nebula so L-Pro is not great, but I don't think it completely kills data.

Any tips on how to approach this?

Thank you so much for the help and apologies if this sounds all a bit stupid, I'm just looking to learn

Yes I'm using the L-Pro (edited the mistake in the original info), I'll try shooting without a filter next time, hopefully soon. At the moment I don't have any software assistance while imaging, but already planning to get an asiair mini for guiding, plate solving etc. That should hopefully solve the framing issue. 

Quote

If you're using gimp you can download the g'mic filters/plugins, there's a decent NR algorithm within called Iain's Denoise, but only use it very very gently otherwise you'll get tadpole like artifacts especially with dim stars in the background

I didn't know about these plugins, worth checking them out for sure! 

Thanks so much for the response, much appreciated.

So for my third project since getting my imaging setup I decided to give a go at the Heart Nebula. UK skies were very clear and the moon was a beautiful 0%. I managed to capture more than 3h of data, which I thought would be enough to get something decently sharp, but I'm still getting a hell of a lot of noise to get some results during processing. I'm assuming that the learning curve for both imaging and processing is vertical  I'm attaching the stacked result if anyone would like to give it a go and see what can be done with it. Maybe ISO 800 is a bit low? I obviously made a big mistake with the framing, but I really couldn't see any detail of the nebulosity in the LCD screen of the camera. Any tips on how to frame faint objects when the camera screen doesn't show anything apart from stars? Otherwise, quite happy with the tracking of the GTI at 2 mins. Any comments/tips/help/suggestions are more than welcome, this is such an amazing hobby and this community is so full of knowledge!

Equipment: WO z61 with flattener, SW Star Adventurer GTI, Canon EOS 2000d, Optolong L-Pro filter. 

Session: 101x120" subs at ISO 800, 20 darks, 20 flats, 20 bias frames. Bortle 5 sky, 0% Moon

Siril: stacking, background extraction, green noise removal, asinh transformation, STARNET for star removal, generalised hyperbolic stretch transformation, star recomposition

GIMP: some more gentle stretching, contrast

FIT file attached for your amusement

Thanks so much for the feedback!

Script stack result.fit

Thanks @teoria_del_big_bang and @Mandy D, I really appreciate your encouraging comments (and everyone else’s for that matter). I think I’m just keen to get sharp results and get rid of all that noise. I’m currently 2h into shooting the Heart Nebula, clear UK skies are such a rarity. Hopefully I’m getting something useful

4 minutes ago, alacant said:

Everything you need is here:

https://siril.readthedocs.io/en/latest/

 

Thank you so much!!

1 hour ago, alacant said:

It's quicker to load the flat sequence, enter the offset value,  pre-process and stack.

Use the flat you just stacked to calibrate the light frames with the same offset; this time register before stacking.

That's it.

To begin with Siril, especially as there's so little to do for DSLR images anyway, I'd recommend doing everything manually. An understanding of what's happening and why is important for troubleshooting when the scrips don't work, and (I find it) quicker anyway... By the time you've moved stuff to where the script expects it to be etc. etc...

HTH

Brilliant! And no bias frames either? I’ll give it a go for sure, thanks for the help.. I’m sure dr google will help answer the long list of questions I‘ll have for sure

2 hours ago, alacant said:

Hi

Good idea. 2000d? So you need only take flat frames in camera. Subtract the offset  manually on the calibration tab. 

Both In-camera bias and dark frames on modern eos' serve only to introduce extra artefacts, so making processing more difficult than necessary. 

Of course, try both ways to see which you prefer.

Cheers and HTH

So to do this, do I need to preprocess without using the scripts? I.e going step by step manually? Or do I use a script without DBF and then calibrate manually on that tab? Apologies if the question is a bit stupid, total beginner here.. Thanks so much

Last night was super clear so I tried my first m31. Faffed around failing alignment and got all flustered, so in the madness I didn't realise the camera was set on JPEG and not RAW!!😱 Anyway, I processed the files to see what came out of them and to get used to the process. This is my first m31 (heavily messed up), but just wanted to share. Equipment: WO z61 with flattener, Canon EOS 2000d, Star Adventurer GTI, Optolong L-Pro. 67x70" subs at ISO 800 (no calibration frames because I wanted to calibrate manually on Siril but realised I have no idea how to do that, if anyone can point me in the right direction that would be great). Processed in Siril: crop, background extraction, noise reduction, green noise reduction, stretching. GIMP: some more gentle stretching. Considering it was from a bunch of JPEGs and not calibrated I'm weirdly happy with it? It's of course very noisy, and a total scrap.. 

37 minutes ago, AstroMuni said:

Let me give you a third option 🙂 Use the GUI interface of Sirilic. It does all the magic of creating the script and running thro Siril. https://siril.org/docs/sirilic/

Really?? hahaha I do love a good software solution.. now, anyone knows how to solve cloudy skies?!

10 hours ago, Padraic M said:

Play around with the calculators on this website: https://astronomy.tools/calculators/dust_reflection_calculator

Those spots are reasonably well defined, so not very far from the sensor. Definitely not something on the t-shirt. Based on your camera pixel size, and the focal length and aperture of your scope, the calculator quotes a distance of 2.7mm from the sensor. Does that sound like there's dust on the Optolong???

Anyway, rather than trying to clean your filter (you risk scratching it, and you will just get more dust on it anyway), getting proper flats will calibrate out any dust or dirt anywhere in the imaging train. Maybe just a quick blow from an air blower would also help.

That's so interesting, I didn't know about that calculator! thanks for the help! Hopefully it's just some dust on the filter, and not something to worry about...

1 hour ago, WolfieGlos said:

What alcant has said is correct, but there is also another way.

You can stack the second nights images together (using a script or otherwise), to create a second stacked file. You can then "stack the stacks" using a second script. Depending where you look online and who you ask, some people frown on it and others use it. Personally, in my limited experience, I've found no issues with it. Give it a try and see what you think.

On this website https://free-astro.org/index.php?title=Siril:scripts there are some freely available scripts to download, and to do this you need the "OSC Preprocessing without DBF" - i.e. stacking without darks, biases or flats. After downloading and placing it in the scripts directory: 

1) Create a new working directory

2) Create a new sub-directory in the new one called "lights"

3) Place both stacked files into the lights directory (you might like to rename the files, I usually call them "result_night_1", 2, 3, etc.

4) Set Siril's working directory to the new one.

5) Run the WithoutDBF script.

Here's one that I'm currently doing, gathered 3 nights of data so far this week. I've had some images with 7 nights worth of data, limited by the short nights or clouds, etc.

 

HTH

 

This is really helpful, thank you very much! I guess I'll have to try and be as precise as possible with framing again?

Another rookie question: can I (I think so but not sure how) get more subs let's say tonight and add them to the stacked file/stack everything together again? If so, how (using Siril)? How do I add flats from different sessions in case? Sorry if it's a bit of a dumb question.

24 minutes ago, alacant said:

Hi

Just over an hour?  Well done. The star field gives nice structure.

2000d? so iso800, lose the dark and in camera bias frames and simply subtract the offset -Canon use 2048 on later models- during calibration. siril makes this easy.

The flat frames don't seem to have corrected, which probably explains the dark blobs and vignetting.

Cheers and HTH

Thanks @alacant. Do you mean I should use ISO800 going forward and not take darks and bias frames? Also, not sure what subtracting the offset means. Any resources you could point me to so I can learn? Thanks so much!

Thanks @Padraic M and @The60mmKid! 
If anyone knows what those circular artefacts are I’d love to know.. maybe something on the sensor/scope/filter? Or maybe while shooting flats there was something on the white t-shirt I used? Anything else? 

12 minutes ago, WolfieGlos said:

For a first image that’s great! Especially for only 1.25 hours. Stars are nice and round and have good colours. What ISO did you use for 55s subs? 

You can add more time to bring out more detail and help to reduce noise.

Taking it a step further, you could try reducing the stars using Starnet allowing the nebulosity to shine through. All part of the learning curve! 

Thanks! I used ISO 1600, it seemed like a good option. Definitely happy as a first attempt for sure, I was trying to understand how to use starnet so definitely something to get to grips with!

Here's the stack @AstroMuni if you or anyone else fancies a go at it, I'd very much appreciate it. 

result.fit

Thanks @AstroMuni! I hope the force is strong in me  I should have mentioned (rookie mistake):

• Stacked in Siril, and I used Siril for background extraction, gradient removal, green noise removal and some stretching as well. I used the deconvolution tool as well, but I think I did something wrong there as I can see funky stuff around stars when zooming in
• GIMP: some more stretching, contrast, saturation

Not sure how much more signal can be extracted from the data I have, I don't want to push the processing too hard to get colours and in the process create a lot of noise. 

Thanks @Mark2022! I'm quite happy with the result, even though I think I overdid it with the processing, it looks a bit noisy to me. I might try remove stars to edit the nebulosity and re-apply them with starnet (need to learn how to do all that but hey). Also, I think that just over 1h of integration time is not that much time (plus a 70% moon). Lots to learn for sure!

Hi everyone, super excited, got my first session last night and went for NGC7000. Needless to say, I have a shedload to learn and a lot of pick up for processing, but wanted to share with you and ask for any advice, comments, suggestions etc. 

Equipment used: Star Adventurer GTI, WO z61 with flat61, Canon eos2000d unmodded, Optolong L-Pro. 86 lights (55s each) for a total of 1h15mins of integration time, 15 darks, 15 flats, 15 bias frames. (I think I have some dust on the sensor, I see there are some circular artefacts in the image). Bortle 6 sky in Berkshire

FIT file at the bottom

NGC7000.fit

1 hour ago, Felias said:

It's not too bad, actually, you just need to get rid of the light pollution. A simple background extraction with Siril, and the most basic arcsinh stretch with Photoshop yields this:

It's definitely there, and you should be able to get a better result departing from your original tiff or fits file, instead of the jpg I have used. It looks like there's coma in the stars, though, so worth checking your lens. And do not be afraid of longer exposure times, it's not too bad if there's a bit of trailing. I did this 50 mm with 8-second exposures, you gain more than you lose by letting the stars trail some:

 

 

Nice result! The learning curve with Siril + GIMP is steep, but definitely worth climbing! Your result on my file looks really good (I was working from a TIFF and exported the final result as a JPEG), actually impressive compared to what I was getting. Thanks for the pointers, really appreciated.

The photo you linked is an absolute masterpiece though, I'm absolutely amazed! I hope one day I'll manage to get something even half that good! 

3 hours ago, Rossco72 said:

It's really hard to say if it's in good focus as there is sooo much coma, or it looks like coma to me from your lens.

The good news is that it is there, and you can see it, but I think the 1s exposures probably won't have helped you much.

Did you keep the camera still for the entire 1000 shots or reframe after each 50 or so?

 

No, stupidly I thought we wouldn't need to do that at 50mm... all part of the learning curve.

54 minutes ago, adyj1 said:

Have you heard of the 300 rule? (or 500 if you have a full frame). Divide 300 by your FL to get a rough approximation of exposure without trailing. So 300/50 = 6 seconds. It is more of a guideline than a rule, so zoom in on a test exposure to check for trailing/eggy stars and adjust accordingly. It is definitely worth spending a few minutes checking this (and focusing at the same time) as the results will be much better. 

I did, but with 4s exposures we were noticing trails, so we reduced to 3s, then 2s then 1s. I hindsight, we where zooming in quite a lot to check for trailing, so that might have been one of the problems.. Do you think it's out of focus as well?