Simone_DB

20 hours ago, 900SL said:

Smoking what? 

😆

The usual! 😉

On 07/12/2023 at 12:21, Mandy D said:

Is Fliss going to get involved in star-gazing?

Well, I think he'd be curious about 30 Doradus! 🙂

Hi to Malc & Fliss. 

Something happened to me a couple of years ago, or so. I was out on my balcony smoking. I looked up more or less at the zenith and I saw a bright point increasing in magnitude, it was not moving or that was my impression. For a fraction of seconds I thought of a supernova (😄), because I couldn't think of anything that my astronomical knowledge could lead me to think about, but the brightness began to dim after a few seconds. The only think I can think about is a satellite flare, but as I said, It didn't seem to move, and besides it was very bright for a polluted sky, that's why I was somewhat startled. I stayed with that idea anyway, for lack of others.

1 hour ago, Ags said:

I feel a science fiction novel coming on 😀

Because the habitable zone of a small red dwarf is so close to the star, I imagine we could squeeze a third habitable world in. Let's say it orbits just outside the red dwarf's habitable zone, so it would be a bit like Mars in our solar system if it only had the red dwarf's light and heat. Of course it would be in the sunlike star's habitable zone and it would be tidally locked to the red dwarf. One side of the planet would have a normal but slow day night cycle with the primary rising and setting as usual, while the side that is near to the secondary star would see the primary rise on blisteringly hot days with two suns, and then set on a freezing "red twilight" dominated by the glowering red dwarf.

You made think about the sci-fi novel "the three body problem" by Liu Cixin, that I've read a few months ago. One cool depiction of the story was (SPOILERS !) about this inhabitated planet in a pseudo-stable orbit somewhere around Alpha Cen or another star of the triple system. People from there were biologically adapted to recurrent extreme conditions, which included periods near one of those stars, during which they completely dehydrated and rendered to some kind of "hibernated" dusty carpets, and epochs, at the contrary, when they were far from all the stars and had to cope with long glaciations. Very cool! I think he won both Nebula and Hugo awards.

20 hours ago, alacant said:

WHY: What Have You

 

😆Oh my, I'm sorry! You're not pompous at all, my friend!

About the SD, of course we cannot explain everything, I guess this concerns electronic engineering! Thanks for the heads up and the clarification about the "offset".

OCIH (Of Course IT Helps 😄)

Alnitak.tif

23 hours ago, alacant said:

I'm guessing the darkest oif the frames is the bias, the next lightest the dark... (?).
Here is the calibration using only the bias and the flat. Gradient notwithstanding, relatively clean.

Now with -what I guess is- the dark. Much noisier.

I next try to find the offset from -what I guess is- the bias, so as to obviate the need for in-camera bias frames. It seems very low. 

Thoughts

I don't know where the noise in your -what I think are- stacked images (this post) originates. So...
Keep`it simple:

• Take a bias frame at 1/4000s in total darkness.
• Use Siril or WHY to find the offset as in the example above.
• Lose the dark and in-camera bias frames
• Calibrate the flat and light frames by subtracting the offset you found above.
• Clean the sensor
• Remoive any sd card from the camera.
• Download directly to your 'phone or a computer.

I've lifted this mostly from our dslr guru's recommendations: ,https://linuxcb.blogspot.com/2023/09/siril-dslr-processing.html

Cheers and HTH

Hello @alacant, thanks for your thoughts. I'm sorry I didn't rename the files in order to easily distinguish them, anyway you guessed it right. I'm really having a hard time with the software, both because I'm trying to get to know all of them together, instead of focusing on one or two, and because they're all a bit tough, at the beginning at least. My second main issue is about identifying or distinguish the various sources of problems (the alignment, the camera, the moonlight, and so on...) and I suppose this is the reason of your suggestions here. So speaking about them:

- I'm taking the bias that way. With the cap and my hand covering the viewfinder of the camera. However, I don't know how to verify the actual achieved "darkness".

- I think I need to understand what you're talking about here (I don't know what the offset is, in this case) and I don't know what WHY is. I'll investigate those things.

- From your link, I get that darks and biases can lead to additional problems if not used (or produced) correctly. I'll investigate that.

- This concerns the point above, I believe. I'll check that out in Siril.

- Yes, my camera is some 12 years old and I never had it cleaned 🙄. Since we're here: there is something else I should check, should I bring it to a shop for maintenance?

- My camera has negligible built-in memory and I don't know how to shoot directly on an external device. I'll check that. I'd like to ask, tough, how come is it different, since you have a physical connection anyway. Wouldn't noise be produced anyway, just elsewhere?

Thanks for the link!

On a side note, just for sharing, Saturday I took some shots of Alnitak surroundings with quite disappointing results. I forgot I was willing to try the built-in automatic shooting tool, which it can maybe be used in "bulb" mode, but I'm afraid I have to figure how to follow objects more precisely. I still have no ideas how do you make several minutes exposures. If I got it right, there is some software that visually follow objects. I made maybe 85 pics 30'' each, and my horsehead was a black silohuette on a blacker background 😄. The Flame Nebula turned out better, tough. I wish I had used a D3100 modded camera I borrowed for that, there's a lot of red in that zone, and in fact, in Siril I have the red channel almost black, only stars are visible. Maybe I'll post a pic of my results.

It was a very cold night, about 1°C, and after shooting Orion, I would have taken one shot of that beautiful moon and Jupiter, but I realized my hands were so cold that I could barely use them, and I struggled to pack things.

I'm now thinking that I should take a break in bothering you all with questions*, and exercise on what I learned so far, study and read.

Thanks again, have a great week you all!

*If I manage to do that 😁

5 hours ago, alacant said:

Hi

The files don't seem to be equivalent or linear. 
Originals:

   

Anyway, there is an almost impossible gradient and a noise pattern which suggests lack of correctly exposed flat frames, circular pattern walking noise or electrical noise; the sort you get when recording to in-camera sd with a mains fed dummy battery. Perhaps send more details of the image acquisition at the telescope and what you did to process up to the point of posting the frames here? Otherwise, we can only guess the cause. Here for example is the red:

I don't feel confident pushing any further than this:

 

But hey, there is some nice detail emerging.

Cheers and HTH

**EDIT... Ah... Just seen. DSLR? So best without dark frames of any kind. Simply subtract the bias from each frame you take. Siril makes this easy.
That may well explain the noise artefacts.

 hI @alacant, Thanks for your time!

I'll attach one sample of lights and calibration files hoping that it can help to understand what I did right and wrong. I shot my flats trying to get a centered histogram, with a white shirt on the scope and a tablet shining a white light.

I always have these circular noisy coloured rings, which, if I recall it right, appear as I use the "extract background" function in Siril, and indeed I wondered what they were caused by. I'm glad you offered an explanation which I have to get, though. I used an old SD with old batteries. Are you saying that it could be the problem? In any case I just bought a new SD card and original Nikon battery.

I can't remember how I processed the image because I've not familiarized with Siril enough, so far, but I followed step by step this video. Unfortunatly it's in italian, but it shows which tools I used.

Can I ask you (and  @AstroMuni as well) how did you manage to obtain that result? As you said, there's alot of information I couldn't extract, and besides you got rid of those awful rings which I made them disappear as well at the expense of said details. The same happened with the Pleiads.

Thanks again the image is very neat! 😍

I'm attaching one of each files I worked with.

DSC_0081.nef DSC_0001.nef DSC_0470.nef DSC_0484.nef

1 hour ago, AstroMuni said:

@alacant your expertise is needed here 🙂

I agree! 😁

1 hour ago, Paz said:

I would recommend a chair like this picture. I have had one for years, it looks rickety but it is infinitely adjustable and works.

I would also recommend just setting up and taking down your scope indoors once a night a few times and you'll iron out any issues without getting cold and demoralised.

I still sometimes do this if I'm out of practice.

Hi Paz, thanks a lot! Luckily things are going better, at least with the alignment. Of course I still do awkard things*, but slowly I feel more confident about the basic operation while I exercise. thanks for the suggestion about the chair, I'll see if I can get one!

*A couple of days ago, for example, this happened: I had just finished with the alignment, which took me half an hour or so, so I took the eyepiece off in order to put the dslr in. But I didn't tighten AC and/or DEC levers properly so, the mount moves because of the weight of the camera...😬So I proceed to swear to all the Gods I know of, and started off, swearing along for all the time needed! I'm pretty sure this little story awoke memories of some people here...🙂

On 21/11/2023 at 18:16, AstroMuni said:

Where is the stacked version please? We just need the stacked version in Tif or FITS format, so you could even just upload it here

Ops, I think my reasoning was wrong: I thought you needed the original files, but I think I know why you don't. Here it is:

M42_DSLR_fin.tif

P.S. In the rush, I uploaded the .tif instead of the .fit

I'll do it again as soon as I get back home from work! 🫤

M42_DSLR.fit

Added the .fit file!

13 hours ago, AstroMuni said:

I took the liberty of quickly running the M45 image thro Siril and here is what I got. Donuts and all 🙂 But looks promising. You will need to get more data to bring out the nebulosity and reduce noise in background @Simone_DB

 

🤩Wow, I'm impressed, and a bit confused! I was expecting, of course, that any of you could make a better job easily but...didn't I upload a jpg pic? I always thought that very little could be done with such files!

1 hour ago, jjohnson3803 said:

Just for an experiment, I opened your Pleiades shot with the default photo editor on my Windows laptop and set both contrast and saturation to 100.  It seemed to reduce the vignetting substantially and the increased saturation brought out star colors (there are a few red stars but maybe a couple are just hot pixels 😉).    FWIW. 

 

 

 

Hi, grazie! 🤗 Well, the Pleiads was actually my first attempt to take some subs, but there are no flat files. One day I'll get back to them!

I managed (I hope), to copy M42 files in Dropbox, for @AstroMuni or whoever wants to give them a look! I included Lightroom metadata because maybe I edited them a bit, but if it's the case really  a bit, like a tad of "remove haze".

https://www.dropbox.com/scl/fo/coit00d6b6ztawedm1vjp/h?rlkey=1i3lx0rn2wntmy0o3p38txcp9&dl=0

Thanks in advance to anybody willing to play around with them! 🙂

Edit: I hope Dropbox's right. If you all use another site, please let me know!

2 hours ago, AstroMuni said:

Thats a great shot. Suggestion - if you post the calibrated image before any histogram transformation etc. here, experts (definitely not me 🙂 ) in this group will be able to process the image and show you the art of the possible.

Thank you! ☺️

I'll drop the file somewhere and post the link, I'm terribly curious! 🙂

On 18/11/2023 at 16:50, wesdon1 said:

@Simone_DB Hi again Simone. My friend, I don't have time to go into detail, as there is a lot to answer here, but i'll do my best! One big issue that stands out to me is you say you used NR for Lights? If yes, DON'T. All the NR is done in post processing with Photoshop, Lightroom or whichever astro-processing software you choose to use! ( as a side note, I too found Siril a headache to use, so I gave up eventually! I use Photoshop now! ) Plus, the NR settings will potentially negatively affect your ability to manipulate/process the light frames in post processing ( it might actually be the reason you couldn't get Siril or photoshop to work with those Lights Files?? )

Your light frames should be taken with your DSLR settings in RAW, NO NR, white balance set to "auto" or "daylight", Metering Mode set to "evaluative", picture Style set to "standard" and your shutter set to "Bulb" ( I recall you are already experienced with daytime photography so I am sure you will know how to set all these settings ) 

1 - In astrophotography it's always a balancing act between getting as long an exposure as possible to maximise signal to noise ratio, while also avoiding light pollution effects and star trailing. In your individual circumstances that could mean anything from 5 seconds exposures to 10 minutes exposures! Then we want to get as many of those long exposures as possible to stack and process later on in post processing. 

2 - Yes Dark frames need to be shot with matching ISO, exposure length and crucially at the exact same temperature. It is actually rather difficult to match DSLR dark frames temperature to Lights temperature, so some people  myself included ) don't bother using them! With a dedicated cooled astro camera, you can easily match the temps with the settings in the software you use with them!

3 - I'm sorry but I can't adequately answer this question because I don't use my cameras histogram for lights, I simply do my Flat frames 5-9 seconds, depending on whether the daytime sky is cloudy, totally blue or something in the middle, like scattered clouds. I must point out though, this is just what personally seems to work for me, other people might well disagree with my methods! Sorry! 

4 - Bias frames are simply the fastest shutter speed possible, in preferably a darkish room at home, with lens cap on but also crucially cover your cameras viewfinder with black Sellotape/insulating tape! People forget that stray light can find it's way through here and onto your cameras sensor! 

I really wish I could have gone into more detail but as you will learn with experience in this hobby, there is a LOT to learn and there are so many variables depending on a multitude of factors, that to write it all down you'd end up with a short novel for an answer!! haha! ( that is the reason why in my first message to you, I recommended you start watching Astrophotography YouTube videos, you will learn so much faster actually seeing a person doing whatever it is they are talking about, which you won't get with just the written word! )

Best Of Luck Simone!

Wes

Hi Wes, thanks a lot for your time and your thoughts!

In order: I don't use NR, glad that you confirm that it's addressed in post processing. I'm using Siril and I also find it a bit tough, but also more detailed than others, according to my very limited experience with this kind of software, at least. But you're saying that you use photoshop; I didn't even know you can stack exposure with that, so I'll dig into it!

I take light frames in RAW, No NR and WB on "Auto". I'll check the metering mode (which I'm not sure if I know what is it).

Now I'm still using 20 or 30 sec of exp, but I'll try to use "Bulb" mode as soon as I can.

1 - I think I'm on the right track here. At the moment, considered my sky and skills, I'm working with 20-30 secs of exposure.

2 - Just one question here. I suppose the temperature we talk about is the sensor's. So if one put the cap on the telescope right after the lights (with no delay to allow the sensor to cool off too much, I mean), and keep on shooting, shouldn't he have the same conditions?

3 - Flat frames are the most mysterious to me, at the moment. So far I used two methods: the first one with a white shirt and a tablet. To have a centered histogram I had to do very short exps, 1/400th of sec or so). When my tablet decided to leave us forever, battery gone, I shot a yellow wall (i didn't know what else to do, I was in session 😅😞 it needed 3'' secs or so. I was shooting a faint target (M101),  so I don't know how to judge the work at the moment. Besides, I could do too few shots of Whirlpool galaxy, so I have to try again.

4 - 🆗I haven't taped the view finder, tough. I'll figure something out!

No worry pal, you (and the others) already gave me a lot of help! I'm watching tutorials, especially about the software. I'll improve my knowledge in time, I hope. 🙂

Lastly, ehm, a question that I'm a bit reluctant to ask, because I'm afraid it's somehow intrusive or cheeky: I'm very courios to compare my work, say for example with the image of M42 above, with someone else's starting from my shots. Is a common practice here on the forum to exchange source files to do such? If you or someone else is willing to have a try, let me know. I'm very courious about such a thing, because I don't have a means of comparison on the results.

Thanks again and have a great day!

Hello, this is my first serious attempt to shoot M42. These are 80x20s ISO 200 shots. I used Biases, Darks and flats. Lightroom, Siril(ic) and some photoshop for stacking/editing. What do you think?

Hello, following the suggestions of many members, I managed to process my first image with Siril/Sirilic. I took 39x20s shots of the Pleiads at ISO 200. I used Darks and Biases (15-16 of each type), but not Flats because I still have to figure out how. The image is very dirty and I think that I'll have the sensor cleaned, because I've never done that in 12 years 😶.

Any technical comment is welcome. Thanks!

M45_DSLR_exp.tif

Hello @Kilohertz, nice Avatar! ☺️

14 hours ago, Swillis said:

I would turn it off. As you point out it will double exposure time, and you are losing control of the process. It may do something to the images which is not ideal, and you would not be able to retrieve the 'original' non-NR image (if that makes sense?)

Try @LandyJon's suggestion of stacking with and without darks and see how much difference it makes. 

 

Hi Simon, thank you! Yes, it makes sense! I don't know either how NR is handled by the camera, that's, if it's a metadata that can turned on and off. Anyway I'll try not to use it.

I'm not sure to have the experience to see the differences with or without darks, but I'll try for sure! 🙂

14 hours ago, LandyJon said:

...to do it 'properly' you want your lights as RAW as you can get them, then deal with the noise in stacking (with calibration frames) and post processing in photoshop (or other).

Yes, that's my idea, too. I think it's ideal to work with unprocessed RAW, I think it could also help to better control and understand the processing with softwares. Plus, I have a gut feeling that denoising works better with external programs that with the embedded software of the camera.

10 hours ago, AstroMuni said:

Download Sirilic https://siril.org/docs/sirilic/ it should make your life easier 🙂 No need to worry about scripts.

 

Thanks Atromuni! I stumbled upon Sirilic just yesterday on a Youtube video. I was looking for Siril and I didn't notice it was talking about the other one☺️I quit watching it, because I thought it was a plug-in or something, but due to what you told me, I have to try it! 🙂

33 minutes ago, LandyJon said:

The darks you could do fresh for each session, thus achieving the (close enough to) same temperature conditions as you light frames.  The advice so far seems to be 30-60s exposures, you'll want a good half to one hour min total exposure time to see some good detail so adding 5 mins worth of lens cap on for 5-10 dark frames could be worth it.

You can then stack (I was going to suggest DSS but its been mentioned, it can stack just lights with a warning box suggesting adding calibration frames but will stack none the less) ... but do a stack with the darks, flats, bias and stack again just flats and bias, see if the darks make enough difference to be worth including in your sessions or not. They likely will but not knowing your sensor or expectations etc. you can make the decision if the added work load is worth the result.

Flats you want the histogram centred, its giving the sensor a complete coverage of mid level illumination, not max brightness (full well) not zero illumination but right in the middle, where it can best differentiate the differences in brightness.  Stacking will then gradient eliminates that from your light frames to even out the sky background, getting rid of that central glow as well as any dark dust spots.

 

Hi @LandyJon, thanks for your suggestions! An actual example of timings is handy for the next session out! And yes, I think I'll go with DSS, I just saw a video about it, and it seems easier for a newbie.

Also, thanks a lot for the clarification about the flats, now I got better why I should take those shots! 😉

I'll check the video as soon as I can. I thank you for your time!

4 hours ago, Swillis said:

Hi @Simone_DB,

I think the number of questions only goes up I'm afraid!  I have something like 6.02214076×10²³ (there is an Italian reference in there for you!)

 

Oh, Amedeo The Great, king of moles! ☺️

4 hours ago, Swillis said:

1) yes, these are the images of the object you are interested in. I checked this page https://astrophotography.app/nikon.php and it recommends an ISO of 200. So that's probably a good place to start. Those with experience of your camera may be able to offer advice also.

Great, thanks a lot. I got a Nikon D5100, so that should be it! And should I keep NR on long exporus on? Sorry for the insistence, that's a feature that doubles exp times, and I'd be glad to avoid it, if the calibration in Siril has the same purpose!

4 hours ago, Swillis said:

2) darks are difficult with a DSLR. As you mention the temperature should be matches to the lights. This is almost impossible to achieve without a cooled astro cam. I use a canon and for that it is recommended NOT to use darks as the canons do something in the background to account for dark signal. I don't know about Nikon's but you could try with and without darks and see what the results are like. Or maybe just forget about this but for not and keep it simpler. (one less thing to get the mandolin out for)

Ok, thank you! As a matter of fact I was contemplating a cooled cam as next purchase, but since I see they don't exactly give them away, I could ignore it for now. All I want to do now, is getting acquainted with the tools.

4 hours ago, Swillis said:

3) take flats every session, as dust can move about. I use an LED drawing pad turned down as for it can go and with a few pieces of paper on top. The method you describe is essentially doing the same thing but using a t-shirt instead of the paper, and a different light source. Some people use a cloudy sky, it doesn't matter as long as it is evenly illuminated on you camera sensor. You might need to play with the exposure length a little to get the histogram where you want it.

Ok 👌! And do I want to put the histogram centered, as the article that I linked says, or should I put it like the light frames?

4 hours ago, Swillis said:

4) yes, put the cap on, and set the exposure to as short as it can go. Bias frames can be reused.

👌

I'll try "Deep sky stacker" and see how it goes.

Simon, I thank you for your time! I hope to be able to show something new soon.

On 10/11/2023 at 11:02, AstroMuni said:

Thats right. And you will come across the terms darks & bias as well so get reading

Hello, after a weekend of reading, doing some activity and accomplishing nothing, this morning I woke up with the dilemma about wether hassle you all once again. Jokes aside, since I suppose you all remember how difficult this thing is at first, you understand how I need a "push" to get past the first hurdles. While I was working, 1.62x10^5 questions came to my mind. I selected a few (all the following questions concern DSOs):

- Light, Bias, Dark and flat frames (so far, I've read this article):

     1) Light frames, as I get it, are the RAW shots. Am I suppose to get visually individual good shots, or can I use longer exposures to save clicks even if results are withishier? Should I keep my ISO low, since I have to stack a lot of shots? Should I use NR reduction on long exp (this in particular is important because it doubles exp times).

     2) Can dark frames be shot just with the (capped) camera? They must match the ISO and exp settings of the lights, so I can make a set a library for different settings that I can use (almost) indefinitely, but the important thing is that they must be shot at the same temperature of the shooting site. Is all that right?

     3) To take Flat frames I can put a white shirt on the telescope with a light source above it, and take shots that match light frames exp, but they have the histogram quite centered. Sky shots often have the histogram crammed on the left side, so how I achive that? I read that the camera orientation matters, hence do I take them every session or I find a way to align the camera always the same?

 4) I've got no particular doubts on Biases. Same temperature and ISO as lights, fast shots. Can they be taken with the capped camera?

- Software: I lived a nightmare. I tried to use Siril, but without light, daks, etc. it's useless. I've tried to download and use some scripts that should allow its use without said files (just to practice), but no luck. So let's just leave it for now. I then tried to use Lightroom together with photoshop, but when I try to export them in the latter, LR says that it failed because "photosop wouldn't open" (same using panorama, photoshop levels or whatever). Is it a common issue? Dispite the message, in a couple of occasion it succeded in creating new frames in LR, but I probably don't know how to use it or they're just too bad. They are some 25 frames of Alnitak surroundings taken at 800 ISO (maybe too much), 13'' exp with NR on long exp on. I hoped, not too much actually,  to see a glimpse of nebulas, but no luck.

I understand those are quite a bunch of questions, and I'm aware enciclopedias were written about what I'm asking, but while I study, if someone wants to comment, share advices, point me to a direction, seen what I have done so far, I'd be immensely grateful. Consider that, for frustration, I ate a lot of spaghetti, played a lot my mandolin and gesticulated a lot more than usual, which denotes a stressful condition for an italian.

Thank you!

1 hour ago, AstroMuni said:

Next step up is to buy a cable to connect mount to a computer & then its a doddle 🙂 The software helps you do the slews, alignment etc. Depending on whether you prefer using a Mac or Windows I would recommend:

- Kstars/Ekos for Mac/Linux

- NINA for Windows

Great, noted! 😀

3 hours ago, Swillis said:

In addition to the channels suggested above I would add 'nebula photos'. Which has some useful tutorials.

I'm checking it out now. I must say the guy is nice and very thorough! 😉Thanks!

20 minutes ago, AstroMuni said:

Thats right. And you will come across the terms darks & bias as well so get reading

🙂👌 I'm going to!

20 minutes ago, AstroMuni said:

I have the same mount as you and you should be able to get pretty good exposures upto 60s (30s as a minimum) without any star drift. But the key to this is getting your scope properly polar aligned. (ie. the mount rotation axis pointing to true north). The polarscope on your mount should help you achieve that quite easily.

I must say this mount is really neat! I am impressed by its precission. I was expecting worse, because of my inexperience. But I must have improved somewhat with alignment, because I had some issues on previous days, but recently everything worked fine. I use an app called "Polar clock".

Thanks!

Oh, ok! It's giving the software a reference to subtract undesired elements kind of technique, I guess? I'll dig into that, thanks a lot!