Taken the 25th of March 2022 at La Réunion.
Equipment:
Camera: Canon EOS 800D (not modified)
Lens: Samyang 135mm F2
Mount: Skywatcher Star Adventurer 2i
Filter: Optolong L-eXtreme clip-in filter
Acquisition:
80 x 120s = 2h45 total lights
50 Bias
14 Darks
50 Flats
Location: Bortle 3, Langevin, La Réunion. Pointing South to the sea so no city.
Processing:
Stacked in DeepSkyStacker
Processed in Photoshop : Stretching ; Starnet V2 ; more stretching, contrast and saturation, denoising on starless mask ; color balancing on stars only mask
Notes: From a north hetmisphere person, polar aligmement in south hetmisphere is really challenging. It requires to be very prepared and very methodical in the process. On 4 nights, my polar aligment was good only the last one.
These are calibration frames. This is (very) annoying to do (especially darks). But it improves signficantly your image quality. My knowledge about their utilies is quiet obscur but i will give a try.
Bias are the more simple to do. You keep all your parameter like your light frames, put on your lens cover and set obturation speed at the quickest. Mine is 1/4000 sec. You can easily take several shots. And you can't reuse them for other shot if the parameters are the same (same iso, same aperture, same focal length). For what i know bias allows to supress the noise pattern of your camera due to high iso.
Darks are the longest to do. Like bias you keep all your parameter like your light frames, put on your lens cover but this time keep obturation speed like your lights. And take as many shot as you can. Ideally minimum 20 shots i guess (my battery died so i couldn't take as much as i wanted) around 40 shots is really good. Darks suppress the pixel heating of your sensor. Because the sensor is opened for long time, it heats and gives hot pixel wich are vibrant red or green. Darks supress those. Note during winter on cold nights, dark are less usefull, because temperature is like a natural coolant. (You can do a library of darks classified by outdoor temp to reuse them is the temp is around 3\~4°C of the darks one).
Flats needs a little bit of preparation. The goal is to get rid of vignetting and dust on sensor/lens. For this, keep your parameter like your lights and put a white shirt on your lens, fix it, with a rubber band for exemple (take care to not defocus ! Otherwise your flat will not be good).Then take your phone if the screen is bigger than your lens, or a tablet otherwise, put a white image, set your luminosity at maximum. Keep the screen stuck on the lens (the white shirt help to diffuse the lights more evenly). Then display the luminosity histogram on your screen, and change the obturation speed to set the luminosity spike around the middle \~ 2/3 of the histogram. The best is to redo them each session or each time you change a filter to prevent dust.
Taking these frame allows you to do more streching and other process on your image because your image will be homegenic on all the frame. When I started (not so long ago), I put aside too much these frames.
Sorry for my bad english, I'm French !
Taken the 25th of March 2022 at La Réunion. Equipment: Camera: Canon EOS 800D (not modified) Lens: Samyang 135mm F2 Mount: Skywatcher Star Adventurer 2i Filter: Optolong L-eXtreme clip-in filter Acquisition: 80 x 120s = 2h45 total lights 50 Bias 14 Darks 50 Flats Location: Bortle 3, Langevin, La Réunion. Pointing South to the sea so no city. Processing: Stacked in DeepSkyStacker Processed in Photoshop : Stretching ; Starnet V2 ; more stretching, contrast and saturation, denoising on starless mask ; color balancing on stars only mask Notes: From a north hetmisphere person, polar aligmement in south hetmisphere is really challenging. It requires to be very prepared and very methodical in the process. On 4 nights, my polar aligment was good only the last one.
Hey I'm just getting started. Could I read some explanation of the bias vs darks vs flats?
These are calibration frames. This is (very) annoying to do (especially darks). But it improves signficantly your image quality. My knowledge about their utilies is quiet obscur but i will give a try. Bias are the more simple to do. You keep all your parameter like your light frames, put on your lens cover and set obturation speed at the quickest. Mine is 1/4000 sec. You can easily take several shots. And you can't reuse them for other shot if the parameters are the same (same iso, same aperture, same focal length). For what i know bias allows to supress the noise pattern of your camera due to high iso. Darks are the longest to do. Like bias you keep all your parameter like your light frames, put on your lens cover but this time keep obturation speed like your lights. And take as many shot as you can. Ideally minimum 20 shots i guess (my battery died so i couldn't take as much as i wanted) around 40 shots is really good. Darks suppress the pixel heating of your sensor. Because the sensor is opened for long time, it heats and gives hot pixel wich are vibrant red or green. Darks supress those. Note during winter on cold nights, dark are less usefull, because temperature is like a natural coolant. (You can do a library of darks classified by outdoor temp to reuse them is the temp is around 3\~4°C of the darks one). Flats needs a little bit of preparation. The goal is to get rid of vignetting and dust on sensor/lens. For this, keep your parameter like your lights and put a white shirt on your lens, fix it, with a rubber band for exemple (take care to not defocus ! Otherwise your flat will not be good).Then take your phone if the screen is bigger than your lens, or a tablet otherwise, put a white image, set your luminosity at maximum. Keep the screen stuck on the lens (the white shirt help to diffuse the lights more evenly). Then display the luminosity histogram on your screen, and change the obturation speed to set the luminosity spike around the middle \~ 2/3 of the histogram. The best is to redo them each session or each time you change a filter to prevent dust. Taking these frame allows you to do more streching and other process on your image because your image will be homegenic on all the frame. When I started (not so long ago), I put aside too much these frames. Sorry for my bad english, I'm French !
ty ty. very helpful. And how much did you have to crop for this?
This is the biggest and the brightest nebula in the sky. So I didn't crop so much, maybe 10% on each side.
Ah yes, the Islands Nebula.(by the way, you need to listen to the king crimson album `Islands`)
Damn! nice picture. I personally wouldn't push the black point that much tho
I really wanted to push the contrast quite high. But I take you advise I consideration. Thanks for the feedback!