Kettle path to astrophoto. Part 3 - Orion Nebula (M42)
Hello geektimes! In the previous part of the Astrochine Notes, we talked about shooting Jupiter, now it's time to move on to more complex objects in more distant space. For example, take the most famous and bright object, the Orion Nebula M42 . As written on Wikipedia, the M42 is about 1344 light-years from Earth and has 33 light-years across. This is the brightest nebula that should be visible even with the naked eye in a dark (not urban) sky.
If anyone knows the constellation and Orion Nebula, a hint in the form of a picture from Stellarium:
Details shooting under the cut.
As mentioned in the first part , ideally for astrophoto nebulae, an equatorial mount is needed, which provides the possibility of long exposures, at least in 1 minute. In my case, the alt-azimuth mount, in addition, the shooting is carried out with the balcony door open, which is very bad in terms of interfering air flows. But the more interesting to get the result.
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The general principle of shooting remains unchanged - it is necessary to accumulate a large number of frames, then folding them, we get a photo with a noticeably better signal-to-noise ratio than in a separate frame.
Baseline: video of 1000 frames, each exposure 0.4s. The exposition was chosen experimentally: at lower frames, the frames are too dark; for larger ones, the picture is too spoiled by air turbulence.
To understand what kind of “material” we have to deal with, a few fragments from individual frames (forgive me, astronomers for such a mockery of the starry sky):
It is also an excellent illustration of why you should not shoot in the winter with the balcony door open (unfortunately the balcony is small and the telescope does not fit on it with the observer). But our task, even from this to get something decent from it.
In addition to the original video, the so-called Dark Frame was also filmed - a small movie with the same shooting parameters, but with the telescope cover closed. Due to this, the program can subtract camera noise from the original frames.
The total size of uncompressed AVI from 1000 frames is about 2 GB. We start processing.
To do this, use the same program PIPP (Planetary Imaging PreProcessor), as for shooting planets. M42 is not a planet, but in our case the program only needs to align the frames and save them to disk. Open in the program the original video and dark frame.
Activate the following options in the program:
- Debayer monochrome frames
- Frame stabilization mode: surface
- Enable quality estimation, 20%
- Output: PNG
PNG is chosen because in the case of such a “source code”, you have to select files manually, the automatic algorithm fails. After about 10 minutes of processing on Core i3, the program creates 200 png-files, which must be selected manually. The principle of selection is clear - to remove blurry or distorted frames, for example, from the above example, you can leave only the top right. The end result: 55 out of 200 frames were left, i.e. a little more than 5% remained from the original video in 1000 frames.
The next stage is the gluing of images. To do this, use the program Deep Sky Stacker . We open in it the pictures saved at the previous step.
We start addition, the program selects and combines frames, the result is already noticeably better, although it needs some work:
Using the “Illumination” curves, we adjust the brightness of dark and light areas:
The final adjustment in Photoshop: "curves" for a more contrasting picture, cropping and removing noise.
More or less final result:
This is certainly not a masterpiece of astronomical photography, but as you can see, even in such conditions, you can get quite interesting results from the balcony in the city.
If anyone knows the constellation and Orion Nebula, a hint in the form of a picture from Stellarium:
Details shooting under the cut.
As mentioned in the first part , ideally for astrophoto nebulae, an equatorial mount is needed, which provides the possibility of long exposures, at least in 1 minute. In my case, the alt-azimuth mount, in addition, the shooting is carried out with the balcony door open, which is very bad in terms of interfering air flows. But the more interesting to get the result.
')
The general principle of shooting remains unchanged - it is necessary to accumulate a large number of frames, then folding them, we get a photo with a noticeably better signal-to-noise ratio than in a separate frame.
Baseline: video of 1000 frames, each exposure 0.4s. The exposition was chosen experimentally: at lower frames, the frames are too dark; for larger ones, the picture is too spoiled by air turbulence.
To understand what kind of “material” we have to deal with, a few fragments from individual frames (forgive me, astronomers for such a mockery of the starry sky):
It is also an excellent illustration of why you should not shoot in the winter with the balcony door open (unfortunately the balcony is small and the telescope does not fit on it with the observer). But our task, even from this to get something decent from it.
In addition to the original video, the so-called Dark Frame was also filmed - a small movie with the same shooting parameters, but with the telescope cover closed. Due to this, the program can subtract camera noise from the original frames.
The total size of uncompressed AVI from 1000 frames is about 2 GB. We start processing.
1. Frame stabilization and image sorting.
To do this, use the same program PIPP (Planetary Imaging PreProcessor), as for shooting planets. M42 is not a planet, but in our case the program only needs to align the frames and save them to disk. Open in the program the original video and dark frame.
Activate the following options in the program:
- Debayer monochrome frames
- Frame stabilization mode: surface
- Enable quality estimation, 20%
- Output: PNG
PNG is chosen because in the case of such a “source code”, you have to select files manually, the automatic algorithm fails. After about 10 minutes of processing on Core i3, the program creates 200 png-files, which must be selected manually. The principle of selection is clear - to remove blurry or distorted frames, for example, from the above example, you can leave only the top right. The end result: 55 out of 200 frames were left, i.e. a little more than 5% remained from the original video in 1000 frames.
Bonding
The next stage is the gluing of images. To do this, use the program Deep Sky Stacker . We open in it the pictures saved at the previous step.
We start addition, the program selects and combines frames, the result is already noticeably better, although it needs some work:
Using the “Illumination” curves, we adjust the brightness of dark and light areas:
The final adjustment in Photoshop: "curves" for a more contrasting picture, cropping and removing noise.
More or less final result:
This is certainly not a masterpiece of astronomical photography, but as you can see, even in such conditions, you can get quite interesting results from the balcony in the city.
Source: https://habr.com/ru/post/399657/
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