This object is too dim for the naked eye or even a telescope, but a digital sensor can capture the color and detail. Pulling detail out of a very dim object involves major noise reduction, which is achieved by making many long exposures while the object is accurately tracked across the sky, and averaging out the noise. Then the dim detail is pulled out by stretching the very dark histogram.
I enjoyed my brief flirtation with astrophotography, but decided it was a bottomless hole and I was better concentrating on subjects for which I had better equipment and processing skills. But it was always a special feeling to be able to capture things we canât see even with a telescope.
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Technical Details
Is this a composite: No
This is from about 4 years ago. The camera details are not in the file and hardly relevant here. I could go into an old LR catalog and dig them out but Iâm pretty sure it was with the Canon 400 f/4 DO on the 7DII modified to be more sensitive to IR (the red color is from hydrogen gas emission). The tracker was an Orion Sirius and probably 4-5 hours of about 2 minute exposures. The software removes noise by averaging stacked frames and the clean result allows you to pull out very dark detail by stretching the histogram â ridiculous amounts by the standards of daytime photography. This one is the result of just beginning to crawl up the ladder of the immensely powerful (and frustratingly complex) astrophotography program, PixInsight.
Iâm posting it with the sketchy information in the spirit that there has been some interest in astrophotography here, and it is an accessible pursuit with the bodies and long lenses many of us have. Trackers and software are extra.
Wow. This is amazing. It looks professional. I love it. I donât know much about this type of photography but the dark space area has some red in it. Is that because the âgases(?)â have spread to that area or is it due to processing? Like I said, I understand little of astroimagery.
Thanks, @Igor_Doncov! The more filamentous reddish areas around the main structure are thinner areas of hydrogen gas emission. Hydrogen molecules are âexcitedâ by high-energy (UV frequency) photons from nearby stars, kicking their lone electron into a higher energy orbit, and then it decays back to its lower energy state with the emission of a photon whose energy (wavelength) is that of red light.
If I had been able to integrate a longer exposure I could have brought out more detail in it. The folks who are more serious about this stuff will image on several nights to collect more data â if they are lucky enough to get several nights of decent skies.
This type of photography amaze me (mainly) for two reasons;
the technicality on it - I am not gadget ou gear acquisition syndrome kind of persons -, all the technology and effort necessary to âget the shotâ, and the pure beauty of those terrible far away and enormous âthinksâ in our Universe sometimes beyond my imagination.
You sure manage to get both.
just beautiful work Diane, and thanks for the scientific explanation too. If your astro work is something that you donât consider to be âseriousâ , then the âreal stuffâ must be truly amazing, because this looks awesome to my uneducated eyes.
Just out of curiosity, is the green color cast on the larger, brighter stars also due to some scientific reason as well? If it is, then this a serendipitous combination of red and green.
Truly outstanding. The combination of factors both in the field and in the computer is so complexâŠI applaud you for learning to master them as far as you wanted to go. Iâd hang this on my wall.
Hi Diane. Admirable work. Astrophotography is technically quite challenging and has had a real explosion with the entrance of digital cameras with high ISO sensitivities. I have been fascinated with it for years but being primarily a large format film photographer it was always out of reach. I started out in photography by photographing new crescent moons and the night sky with 35 mm equipment on ISO 400 slide film but could never get anything beyond bright star constellations. When tracking telescopic mounts appeared I started wondering if it would be possible to get the night sky on color film. Six years ago I managed to capture on film an interesting star trail pattern over a three hour exposure on 4x5. I started building and programming a barn door tracker capable of moving my 4x5 camera. Last Friday I made my first tracked wide field exposure but it was cut short due to fog. I am very anxious to see what I got and your photo has pushed my excitement even more.
Iâm not sure the greens in stars is a natural color occurance. I think if you color correct the highlights you can eliminate it and enhance further the H-alpha emissions of the nebula.
Thanks for your post, Iâm really excited to see what I captured.
Thanks everyone! @Ed_McGuirk, the serious stuff is REALLY amazing!! There are a number of amateur astronomy forums that are amazing, and https://apod.nasa.gov/apod/astropix.html has some posts from serious amateurs. It can be difficult to distinguish some of them from Hubble imagesâŠ
You are correct that the green is not accurate. I may have posted an unfinished image, as PixInsight would have corrected it, but not automatically. My learning path was like scrambling up a cliff of loose stones⊠And if I had posted a picture on their forum that was âfinishedâ in PS I would have justly been branded a heretic.
@Youssef_Ismail, film does have some advantages over digital for longer exposures. I look forward to what you get â and kudos for being able to track with a 4x5 on a barn door tracker!
Thanks @Igor_Doncov! I wouldnât make them white as stars do have color, varying with their temperature from red to orange to white to blue â but not green. It can be rendered accurately with the correct exposure. Picture trying not to blow out stars while getting enough exposure on very dim nebulosity. Mind-boggling by normal standards, but with the right exposure and NR by stacking and averaging enough frames, the dark end of the histogram can be stretched without blowing out the stars, retaining their true color.
