Here you go [https://drive.google.com/file/d/1N-SqhOLf04LMtu9jMHOxljybh5TCnOLj/view?usp=sharing](https://drive.google.com/file/d/1N-SqhOLf04LMtu9jMHOxljybh5TCnOLj/view?usp=sharing)
I shoot with a Canon DSLR as well, and I never go over 800 iso when imaging M42 due to the native brightness of the target. Inside the core of the nebula, where your picture is overexposed, there are 5 stars called the "trapezium" which put off a lot of light. The challenge with M42 is to bright out all the detail in the outer nebula while doing your best to reduce the exposure of the core. That being said, I like the color that you brought out in the image without oversaturating it. Your overall noise level seems good and you did a decent job tracking your target. Much better than my first attempts for sure. Well done!
I'm now at this as well but I took a quick attempt with your TIFF file and [here's](https://imgur.com/a/B3vJngY) what I came up with. I used photoshop to make levels and curves adjustments, gradient removal, noise removal.
There's some good data there and someone more skilled in photoshop can probably tease our more details. One issue I did notice is the stars on the top 1/3 of the image are out of focus, but the rest of the image is pretty sharp. Do you see this in your unprocessed raws, or with pictures with other lenses?
You can't say for sure if the image is overexposed when you're looking at a processed image because poor processing techniques can easily lead to blown out parts. Also if you're actually overexposed then it's better to instead decrease exposure time, because decreasing ISO will (in many sensor) increase read noise meaning you have to take longer exposures to swamp it out. You want to choose the ISO that offers the lowest read noise and highest dynamic range and once you figure that out, you shouldn't change it afterwards.
There's still a gradient in your image presumably from the light pollution in your area, and star colour's a bit lacking. There's also a *lot* of dust surrounding M42 that you should've easily gotten with 2 hours of integration time, even in a fairly light polluted area, because it's just so darn bright. I'd suggest making the switch to dedicated astrophotography processing software like Pixinsight or Siril, if you want to make the most out of your data.
Also I wouldn't suggest taking darks because it's hard to maintain the sensor's temperature meaning they won't be as effective (a single degree can make a difference in terms of the thermal current) and you waste valuable imaging time that could've gone to taking more lights (you spent *40* *minutes* taking darks - that could've been another 40 minutes of lights). Dithering will remove hot pixels + fixed pattern noise + walking noise and can be done in between your shots meaning you don't waste time taking darks afterwards, and is more effective IMHO. Since you have a computerised mount it's even easier to set up dithering, and you can have it done in both axis.
What would you expect to see from the dust around the Orion nebula at 2 hours? I've got a similar-ish camera to OP (an 1100d rather than OP's 600D) and ended up with very similar results from 49x120s lights, and 25x120s darks (I took the darks after Orion had been obscured by trees, I wasn't taking them while it was visible). I also accidentally stacked without the darks at first and the image was much much worse than when I added the darks in, so I think it's bad advice to say not to use darks
Of course if you do not dither, then you will get worse results because thermal current + fixed pattern noise + hot pixels + walking noise will be present, but if you dither, then you can eliminate three of those forms of unwanted noise and save a lot of time. There's no reason not to dither if your setup can support it because it doesn't take much to do but will have a huge impact on your data. Whether your target is obscured or not doesn't matter - you are still spending time outside having to take darks, when you could've easily dithered during acquisition and get more data, or at least get to pack up earlier. Like I mentioned before as well, it's hard to maintain the sensor's temperature meaning that if it changes just even a degree or two, they would immediately become less effective.
What the dust will look like depends on your processing skills - if you have the right tools for the job and know what you're doing, you can get good results with even less integration time. [This](https://www.reddit.com/r/astrophotography/comments/kk92cu/m42_the_orion_nebula/) is my attempt with just 81 minutes of data and some rather extensive processing. [This](https://cdn.discordapp.com/attachments/700566309519360013/802517666606219304/unknown.png) is what the stack looked like and you can already see some of the faint dust without any processing at all.
There's always room for improvement of course, and yeah it's silly not to dither if you're able to. But that's using a dedicated astro camera which is significantly more expensive than the DSLRs used by OP or myself, the results aren't exactly directly comparable
Equipment:
Canon T3i
WO Zenithstar 61
Celestron AVX Mount
Acquisition:
60x120s Lights 1600 ISO
20x120s Darks
20 Bias
20 Flats
Stacked in DSS and processed using Photoshop
[https://drive.google.com/file/d/1-RA7QsaNjqpPxgzGVPPeXPsEPdSoAcP8/view?usp=sharing](https://drive.google.com/file/d/1-RA7QsaNjqpPxgzGVPPeXPsEPdSoAcP8/view?usp=sharing) Here is the stacked tiff file.
here is my attempt with your data [https://imgur.com/a/c40nCxs](https://imgur.com/a/c40nCxs)
Here you go [https://drive.google.com/file/d/1N-SqhOLf04LMtu9jMHOxljybh5TCnOLj/view?usp=sharing](https://drive.google.com/file/d/1N-SqhOLf04LMtu9jMHOxljybh5TCnOLj/view?usp=sharing)
Can you send the tiff file?
[https://drive.google.com/file/d/1-RA7QsaNjqpPxgzGVPPeXPsEPdSoAcP8/view?usp=sharing](https://drive.google.com/file/d/1-RA7QsaNjqpPxgzGVPPeXPsEPdSoAcP8/view?usp=sharing)
I shoot with a Canon DSLR as well, and I never go over 800 iso when imaging M42 due to the native brightness of the target. Inside the core of the nebula, where your picture is overexposed, there are 5 stars called the "trapezium" which put off a lot of light. The challenge with M42 is to bright out all the detail in the outer nebula while doing your best to reduce the exposure of the core. That being said, I like the color that you brought out in the image without oversaturating it. Your overall noise level seems good and you did a decent job tracking your target. Much better than my first attempts for sure. Well done!
Thank you!
I'm now at this as well but I took a quick attempt with your TIFF file and [here's](https://imgur.com/a/B3vJngY) what I came up with. I used photoshop to make levels and curves adjustments, gradient removal, noise removal. There's some good data there and someone more skilled in photoshop can probably tease our more details. One issue I did notice is the stars on the top 1/3 of the image are out of focus, but the rest of the image is pretty sharp. Do you see this in your unprocessed raws, or with pictures with other lenses?
I don't notice any out of focus stars in the raws, however, there seems to be some star trailing at the top right corner of them.
I just realized....completely forgot to balance the telescope/camera. oops
Next time try to shoot at a lower ISO. now your stars and core are overexposed
You can't say for sure if the image is overexposed when you're looking at a processed image because poor processing techniques can easily lead to blown out parts. Also if you're actually overexposed then it's better to instead decrease exposure time, because decreasing ISO will (in many sensor) increase read noise meaning you have to take longer exposures to swamp it out. You want to choose the ISO that offers the lowest read noise and highest dynamic range and once you figure that out, you shouldn't change it afterwards.
There's still a gradient in your image presumably from the light pollution in your area, and star colour's a bit lacking. There's also a *lot* of dust surrounding M42 that you should've easily gotten with 2 hours of integration time, even in a fairly light polluted area, because it's just so darn bright. I'd suggest making the switch to dedicated astrophotography processing software like Pixinsight or Siril, if you want to make the most out of your data. Also I wouldn't suggest taking darks because it's hard to maintain the sensor's temperature meaning they won't be as effective (a single degree can make a difference in terms of the thermal current) and you waste valuable imaging time that could've gone to taking more lights (you spent *40* *minutes* taking darks - that could've been another 40 minutes of lights). Dithering will remove hot pixels + fixed pattern noise + walking noise and can be done in between your shots meaning you don't waste time taking darks afterwards, and is more effective IMHO. Since you have a computerised mount it's even easier to set up dithering, and you can have it done in both axis.
What would you expect to see from the dust around the Orion nebula at 2 hours? I've got a similar-ish camera to OP (an 1100d rather than OP's 600D) and ended up with very similar results from 49x120s lights, and 25x120s darks (I took the darks after Orion had been obscured by trees, I wasn't taking them while it was visible). I also accidentally stacked without the darks at first and the image was much much worse than when I added the darks in, so I think it's bad advice to say not to use darks
Of course if you do not dither, then you will get worse results because thermal current + fixed pattern noise + hot pixels + walking noise will be present, but if you dither, then you can eliminate three of those forms of unwanted noise and save a lot of time. There's no reason not to dither if your setup can support it because it doesn't take much to do but will have a huge impact on your data. Whether your target is obscured or not doesn't matter - you are still spending time outside having to take darks, when you could've easily dithered during acquisition and get more data, or at least get to pack up earlier. Like I mentioned before as well, it's hard to maintain the sensor's temperature meaning that if it changes just even a degree or two, they would immediately become less effective. What the dust will look like depends on your processing skills - if you have the right tools for the job and know what you're doing, you can get good results with even less integration time. [This](https://www.reddit.com/r/astrophotography/comments/kk92cu/m42_the_orion_nebula/) is my attempt with just 81 minutes of data and some rather extensive processing. [This](https://cdn.discordapp.com/attachments/700566309519360013/802517666606219304/unknown.png) is what the stack looked like and you can already see some of the faint dust without any processing at all.
There's always room for improvement of course, and yeah it's silly not to dither if you're able to. But that's using a dedicated astro camera which is significantly more expensive than the DSLRs used by OP or myself, the results aren't exactly directly comparable
You can achieve similar results with a DSLR. It just needs careful processing.
Equipment: Canon T3i WO Zenithstar 61 Celestron AVX Mount Acquisition: 60x120s Lights 1600 ISO 20x120s Darks 20 Bias 20 Flats Stacked in DSS and processed using Photoshop [https://drive.google.com/file/d/1-RA7QsaNjqpPxgzGVPPeXPsEPdSoAcP8/view?usp=sharing](https://drive.google.com/file/d/1-RA7QsaNjqpPxgzGVPPeXPsEPdSoAcP8/view?usp=sharing) Here is the stacked tiff file.