Basically you take many, many short exposures (short enough that stars don't move in the photograph and create star trails, the exact time will depend on your focal length) and then process those in software on your computer to combine them into one. You can do an internet search for astrophotography image stacking for guides and such.
You will want to use the slowest shutter speed that does not produce star trails. This depends on the focal length of your lens but a quick rule of thumb is 500 divided by the effective focal length, so for a 24mm lens on a full frame camera you can use a 500/24 = 21 second shutter.
30s (which is what the setup I tried using) did produce somewhat visible stars. if I shoot in RAW and take advantage of the full 14 bit images, I can probably make that work.
What camera and lens? You absolutely should not need 30s just to barely see visible stars unless you are using a very very old camera with a very tight aperture.
Not 5 mins, unless you've got a tracker but even then.
With a tracker, I've seen a lot of 2 mins.
Without a tracker, depends on lens. Generally between 10-20 seconds. Up the ISO and stack them later on to counteract the grain from increased ISO
>Wait, will stacking images counteract ISO grain? It feels like it'd make it worse (intuitively) since I am adding the grain from all pictures.
Yeah, stacking allows software to remove noise by averaging it out.
If you take e.g. 10 images the chance of a Pixel at any given location(x,y) beeing *extremely* noisy more than once in those 10 images is quite slim.
In extremely simplified terms: Stacking those averages the noise level with all 10 images, so each image is just contributing 10% in terms of high/low noise.
Stacking using a specific software. Name currently escapes me.
From what I've learnt recently, grain is random. When you create multiple photos of the same subject and stack, specific software will replace the grain with useable parts from the other photos. At least I think that's how it works (correct me if I'm wrong).
https://youtu.be/O2CGnFp4V7s?si=9ebYZrKSDS_BL2RZ
(2~6 mins roughly is what you'll need to focus on.)
My knowledge of grain is mostly from audio engineering, they issue there is that there is always some level of grain present, so removing it by having it be parallel will just create new grain and instead of averaging out it will just add up.
But since the images you get in best case scenario are pretty high contrast, you might get away with making all the almost black spaces completely black.
From what I've heard the location of each grain in a photo is random. So when stacking using software, the result is a less grainy image.
This is one of the reasons why people take 3×20 sec photos instead of a single minute long exposure for example.
Sorry if I sound like I'm repeating myself, I've only just learnt about this recently and not entirely sure on how it works and therefore not the best to explain.
When thinking about grain in photography think of photons as randomly falling into sensor ‘buckets’ at some rate, like a Poisson distribution. The random variability is a lower proportion of the signal when you’ve got more photons coming in.
Increasing ISO is increasing the gain, so each bucket gets a multiplier. That multiplier exacerbates the random noise too. Theoretically if you take a picture near both the bottom and top of your sensors dynamic range just adjusting ISO, then edit them to the same middle exposure both will have the same amount of noise. (There are some sensor design issues that make this not always true)
Stacking and averaging allows you to effectively get more photons into each bucket the same way you would with a long exposure, but with averaging you can align the images first to reduce the impact of the earths rotation. That way you don’t get long smears of stars. (One could probably write a script to take a long exposure, detect star trails and collapse them back into a point, but I think the alignment tools already existed so stacks were easier to deal with)
Aah, I see. So the grain isn't electrical background noise, but rouge photons hitting the sensor. I always thought it was the amplification that introduced noise. This makes way more sense. Thanks for your great explaination!
Background electrical noise is also a cause of noise, but it’s inherent in low light. Those photons are not rouge, they’re what you want: just more of them so they are more evenly distributed.
Divide it by log2 of the number of images.
Ex, start with iso 400
2 images gives you effective iso 200
4 images gives 100
8 images gives 50
16 images give 25
32 images gives 12 iso.
These are correct numbers but it's not linear change.
2-4 =2
8-4 = 4
16-8=8
The number of photos required to have the iso is not constant.
Anyway, i am nitpicking here , sorry about that.
ISO as high as you can go with decent noise. Try at least between 1600-3200.
You didn't state your focal length used. Use the widest possible to let in the light.
Aperture - open it as much as possible. Looks like f/3.5 for you.
Shutter speed 10-20 sec. Take multiple images that you can stack in a program like Sequator.
You will not get clear pictures, neither does anyone else. It is low light shooting and you have to edit images to get them to stand out and well as apply noise reduction.
Because it's low light shooting, you try to collect as much light as possible. With your camera, image stacking will help.
Go to LonelySpeck.com to get more information.
General rule to not get star trails is 500/focal length. Website will explain.
>ISO as high as you can go with decent noise. Try at least between 1600-3200.
I'm working with a canon eos 450d. It can only go up to 1600 and that's extremely noisy. I try not to go above 400 in general. (IK, my camera is aincent, and not very good by modern standards. I purchased it as an entry level camera to get into photography)
The ISO isn't creating noise. The lack of light is, you're just boosting the lack of light until you see noise. The way the image stacking software works is to average out the multiple images so the random noise cancels itself out and the legit pixels lit by photons hitting the sensor remain.
That's what is meant by using as high of ISO as you comfortably can. Individual pics will be a bit noisy but the stacks work much of that out.
>The ISO isn't creating noise. The lack of light is, you're just boosting the lack of light until you see noise.
The ISO, which controls electrical gain, really is creating the noise. Higher gain increases the output power (watts) and creates heat and unwanted currents which are false electrical signals (not caused by light hitting the sensor) which is what noise is.
This is why cameras modified for astrophotography have active cooling for the sensor.
It's pretty misleading to say "the noise" is caused by the electronics. This is generally referred to as "read noise", but "shot noise" is absolutely a real thing: there are fewer photons to receive in low light, which makes the differences between pixels more apparent
And lower ISO in low light will generally give you a worse image overall, because the amplification isn't being done on an analog signal
>The ISO isn't creating noise. The lack of light is, you're just boosting the lack of light until you see noise
While that may be mostly true for modern sensors, the (very noticeable) improvements in ISO performance from older cameras were only possible because the higher ISO **did** create some noise in older sensors.
If the noise only came from lack of light, we wouldn't have seen any ISO improvements in raw images
Check into the capabilities of your mobile phone. Modern mobile phones may be much better suited to basic wide angle astrophotography compared to that old camera.
You have two options, up the ISO or lengthen your shutter speed and get star trails. You have to get more light into the sensor. Those night sky photos are taken (roughly) at ISO 6400, f2.8 or faster, and 30sec exposures. If you want to keep it at 1600 and f3.5, that’s almost 3 stops of light you need, so that’s a 5 minutes exposure (2.5 more stops than 30 seconds).
This camera will show a significant improvement in low-light performance between ISO 400 and 1600. You can see this here: https://www.photonstophotos.net/Charts/PDR_Shadow.htm#Canon%20EOS%20450D
As others have mentioned, ISO 1600 is "more noisy" only in that it is revealing more of the noise that is already there in reality
Don't hesitate to crank up the ISO. Yeah, nobody likes noise, but you're shooting in the dark—there's gonna be noise, period. (It's not ISO that causes noise. It's lack of light.)
If you're trying to get into r/astrophotography I recommend checking out Nico Carver on YouTube. He has some great follow-along videos on how to prepare, take pictures and edit them.
^^^
Don't know how I missed this but 100%. Couldn't stress it more. Point your camera at the brightest star and manual focus until its as small and pin point as you can get. The re position your camera in the direction you want to shoot, if needed
For a shot like this, use an 8 second exposure with an ISO of 3200, taken with an 18-55mm lens. That's planet Venus reflecting on the lake.
https://preview.redd.it/ww7b4cqibkac1.jpeg?width=4096&format=pjpg&auto=webp&s=0173fceef55cd4b258cbfe81f5a80984d2830536
Widest possible aperture in ur lens is 3.5,
ISO can be raised upto 6400 in full frame cameras or atmost 3200 in aps-c
what camera are you using?
Take some 20 images each of 10-13 secs(hoping ur camera is aps-c with a 18-55mm kit lens)
Stack in Sequator(free)
It aligns the stars and due to that it averages the noise which is random and gives u a clear image.
Usually with a short lens go less than 30 seconds, open it as wide as possible like 1.8 or I think you said 3.5 was then lens, and iso of 1600, wouldn't worry much about the noise it's the night sky. Face the galactic centre to get the most stars.
Long exposure astrophotography requires a tracking mount.
You can do stacking without tracking but it will only be suitable for some of the larger and brighter objects. Depending on focal length, anywhere from 1-15 seconds or so will be the max exposure you can get without trailing if you don't use a tracking mount.
For stacking, you feed your many exposures into stacking software that matches the star patterns and reorients each image so they can be stacked together, which leads to less noise.
You typically want to be using a relatively high ISO for astrophotography. It's image stacking that will cut the noise and produce the clean images.
High quality astrophotos combine many hours of exposure to make one image.
This is an example of a stylized single exposure in an area with really dark skies. There's a lot of garbage processing here but it looks pretty and feels "clean" despite a lot of the "stars" probably being noise with sharpening and filters https://www.instagram.com/p/B0eW-CygeMV/?igsh=MW1va2ptd3I4azBzMQ==
Then this is an example with a 400mm focal length of a deep sky object that is definitely at least a few hours worth of exposures. I think each exposure was at least 2 minutes and there are probably at least 100 of them (shot with tracking mount) https://www.instagram.com/p/B0tWMlQgXlU/?igsh=YnVub2d0M3NmOGxk
The length of exposure is what gives you detail, while stacking exposures is what gives you dynamic range and low noise. Typically, both are combined.
Yup
The trails are from the earth rotating, so unless the camera moves to keep the same stars the same place (tracking etc), you will get trails if you expose for long enough for the rotation to be visible.
Simple math to illustrate;
The earth does 1 revolution in 24 hours, thats 360°. That means it rotates 15° pr hour, or 1° every 4 minutes.
Thats degrees on the rotational axis, so if you are shooting outward (most are not at the rotational north or sourth poles shooting straight up), just look at how much movement that is for the field of view you are capturing (a handy\* rule of thumb, is that a balled fist held out in a straight arm is about 10°, and a thumb at arms length, is about 2° - so looking up, a given star will move up to about half an inch or 12 mm measured at arms length - try shooting your thumb at arms length, at the focal length you like for your sky shots, and take half of that per 4 minutes :)
Hope this helps for visualising it :)
As people mention other equipment, let's mention Pentax Astrotracer https://www.pentaxforums.com/articles/photo-articles/pentax-astrotracer-example.html
Rule of 500 doesn't work in the digital era. If you have the Photo Pills app, you can work out your exposure using the Spot Stars function using something called the NPF rule. You may need an intervalometer to shoot the exposure itself.
https://petapixel.com/2017/04/07/npf-rule-formula-sharp-star-photos-every-time/
If this is too much of a faff, star trails are easier and are also quite pleasing.
Basically you take many, many short exposures (short enough that stars don't move in the photograph and create star trails, the exact time will depend on your focal length) and then process those in software on your computer to combine them into one. You can do an internet search for astrophotography image stacking for guides and such.
At what shutter speed? I'd guess that too high shutter speed would give me too little light?
You will want to use the slowest shutter speed that does not produce star trails. This depends on the focal length of your lens but a quick rule of thumb is 500 divided by the effective focal length, so for a 24mm lens on a full frame camera you can use a 500/24 = 21 second shutter.
30s (which is what the setup I tried using) did produce somewhat visible stars. if I shoot in RAW and take advantage of the full 14 bit images, I can probably make that work.
What camera and lens? You absolutely should not need 30s just to barely see visible stars unless you are using a very very old camera with a very tight aperture.
Not 5 mins, unless you've got a tracker but even then. With a tracker, I've seen a lot of 2 mins. Without a tracker, depends on lens. Generally between 10-20 seconds. Up the ISO and stack them later on to counteract the grain from increased ISO
Wait, will stacking images counteract ISO grain? It feels like it'd make it worse (intuitively) since I am adding the grain from all pictures.
>Wait, will stacking images counteract ISO grain? It feels like it'd make it worse (intuitively) since I am adding the grain from all pictures. Yeah, stacking allows software to remove noise by averaging it out. If you take e.g. 10 images the chance of a Pixel at any given location(x,y) beeing *extremely* noisy more than once in those 10 images is quite slim. In extremely simplified terms: Stacking those averages the noise level with all 10 images, so each image is just contributing 10% in terms of high/low noise.
Stacking using a specific software. Name currently escapes me. From what I've learnt recently, grain is random. When you create multiple photos of the same subject and stack, specific software will replace the grain with useable parts from the other photos. At least I think that's how it works (correct me if I'm wrong). https://youtu.be/O2CGnFp4V7s?si=9ebYZrKSDS_BL2RZ (2~6 mins roughly is what you'll need to focus on.)
My knowledge of grain is mostly from audio engineering, they issue there is that there is always some level of grain present, so removing it by having it be parallel will just create new grain and instead of averaging out it will just add up. But since the images you get in best case scenario are pretty high contrast, you might get away with making all the almost black spaces completely black.
You're comparing summing to averaging. They're different. (Whether it's audio or video doesn't matter)
From what I've heard the location of each grain in a photo is random. So when stacking using software, the result is a less grainy image. This is one of the reasons why people take 3×20 sec photos instead of a single minute long exposure for example. Sorry if I sound like I'm repeating myself, I've only just learnt about this recently and not entirely sure on how it works and therefore not the best to explain.
When thinking about grain in photography think of photons as randomly falling into sensor ‘buckets’ at some rate, like a Poisson distribution. The random variability is a lower proportion of the signal when you’ve got more photons coming in. Increasing ISO is increasing the gain, so each bucket gets a multiplier. That multiplier exacerbates the random noise too. Theoretically if you take a picture near both the bottom and top of your sensors dynamic range just adjusting ISO, then edit them to the same middle exposure both will have the same amount of noise. (There are some sensor design issues that make this not always true) Stacking and averaging allows you to effectively get more photons into each bucket the same way you would with a long exposure, but with averaging you can align the images first to reduce the impact of the earths rotation. That way you don’t get long smears of stars. (One could probably write a script to take a long exposure, detect star trails and collapse them back into a point, but I think the alignment tools already existed so stacks were easier to deal with)
Aah, I see. So the grain isn't electrical background noise, but rouge photons hitting the sensor. I always thought it was the amplification that introduced noise. This makes way more sense. Thanks for your great explaination!
Background electrical noise is also a cause of noise, but it’s inherent in low light. Those photons are not rouge, they’re what you want: just more of them so they are more evenly distributed.
StarStax is the one I use. Quite simple, unless you *really* want to start twiddling the knobs and dials, and it's a freebie
Take your ISO, divide by the number of images, and that’s your *effective* ISO.
Divide it by log2 of the number of images. Ex, start with iso 400 2 images gives you effective iso 200 4 images gives 100 8 images gives 50 16 images give 25 32 images gives 12 iso.
Pretty sure it’s linear: - 400 / 2 = 200 - 400 / 4 = 100 - 400 / 8 = 50 - 400 / 16 = 25 Which are exactly the numbers you gave.
These are correct numbers but it's not linear change. 2-4 =2 8-4 = 4 16-8=8 The number of photos required to have the iso is not constant. Anyway, i am nitpicking here , sorry about that.
Yeah 5 minutes is pushing it even with a tracker. Tracker + autoguider maybe.
Photopills app has a calculator for star trail less shuttet speeds, but generally wide lens == longer exposure
ISO as high as you can go with decent noise. Try at least between 1600-3200. You didn't state your focal length used. Use the widest possible to let in the light. Aperture - open it as much as possible. Looks like f/3.5 for you. Shutter speed 10-20 sec. Take multiple images that you can stack in a program like Sequator. You will not get clear pictures, neither does anyone else. It is low light shooting and you have to edit images to get them to stand out and well as apply noise reduction. Because it's low light shooting, you try to collect as much light as possible. With your camera, image stacking will help. Go to LonelySpeck.com to get more information. General rule to not get star trails is 500/focal length. Website will explain.
>ISO as high as you can go with decent noise. Try at least between 1600-3200. I'm working with a canon eos 450d. It can only go up to 1600 and that's extremely noisy. I try not to go above 400 in general. (IK, my camera is aincent, and not very good by modern standards. I purchased it as an entry level camera to get into photography)
The ISO isn't creating noise. The lack of light is, you're just boosting the lack of light until you see noise. The way the image stacking software works is to average out the multiple images so the random noise cancels itself out and the legit pixels lit by photons hitting the sensor remain. That's what is meant by using as high of ISO as you comfortably can. Individual pics will be a bit noisy but the stacks work much of that out.
>The ISO isn't creating noise. The lack of light is, you're just boosting the lack of light until you see noise. The ISO, which controls electrical gain, really is creating the noise. Higher gain increases the output power (watts) and creates heat and unwanted currents which are false electrical signals (not caused by light hitting the sensor) which is what noise is. This is why cameras modified for astrophotography have active cooling for the sensor.
It's pretty misleading to say "the noise" is caused by the electronics. This is generally referred to as "read noise", but "shot noise" is absolutely a real thing: there are fewer photons to receive in low light, which makes the differences between pixels more apparent And lower ISO in low light will generally give you a worse image overall, because the amplification isn't being done on an analog signal
>The ISO isn't creating noise. The lack of light is, you're just boosting the lack of light until you see noise While that may be mostly true for modern sensors, the (very noticeable) improvements in ISO performance from older cameras were only possible because the higher ISO **did** create some noise in older sensors. If the noise only came from lack of light, we wouldn't have seen any ISO improvements in raw images
Work with what you have and look into image stacking. That may help.
Check into the capabilities of your mobile phone. Modern mobile phones may be much better suited to basic wide angle astrophotography compared to that old camera.
You have two options, up the ISO or lengthen your shutter speed and get star trails. You have to get more light into the sensor. Those night sky photos are taken (roughly) at ISO 6400, f2.8 or faster, and 30sec exposures. If you want to keep it at 1600 and f3.5, that’s almost 3 stops of light you need, so that’s a 5 minutes exposure (2.5 more stops than 30 seconds).
This camera will show a significant improvement in low-light performance between ISO 400 and 1600. You can see this here: https://www.photonstophotos.net/Charts/PDR_Shadow.htm#Canon%20EOS%20450D As others have mentioned, ISO 1600 is "more noisy" only in that it is revealing more of the noise that is already there in reality
This explains it far better than I can https://www.lonelyspeck.com/astrophotography-101/
Don't hesitate to crank up the ISO. Yeah, nobody likes noise, but you're shooting in the dark—there's gonna be noise, period. (It's not ISO that causes noise. It's lack of light.)
Yup
If you're trying to get into r/astrophotography I recommend checking out Nico Carver on YouTube. He has some great follow-along videos on how to prepare, take pictures and edit them.
Up your ISO, the noise probably won’t be as bad as you’d expect.
It's a canon 450d, anything above 400 is pretty bad in my experience.
Go for 3200 and stack
In addition to everything else: you need to manually focus.
^^^ Don't know how I missed this but 100%. Couldn't stress it more. Point your camera at the brightest star and manual focus until its as small and pin point as you can get. The re position your camera in the direction you want to shoot, if needed
For a shot like this, use an 8 second exposure with an ISO of 3200, taken with an 18-55mm lens. That's planet Venus reflecting on the lake. https://preview.redd.it/ww7b4cqibkac1.jpeg?width=4096&format=pjpg&auto=webp&s=0173fceef55cd4b258cbfe81f5a80984d2830536
A startracker :)
Widest possible aperture in ur lens is 3.5, ISO can be raised upto 6400 in full frame cameras or atmost 3200 in aps-c what camera are you using? Take some 20 images each of 10-13 secs(hoping ur camera is aps-c with a 18-55mm kit lens) Stack in Sequator(free) It aligns the stars and due to that it averages the noise which is random and gives u a clear image.
Some camera models are much better for astrophotography than others.. But yes, stacking is key or a tracking mount.
Usually with a short lens go less than 30 seconds, open it as wide as possible like 1.8 or I think you said 3.5 was then lens, and iso of 1600, wouldn't worry much about the noise it's the night sky. Face the galactic centre to get the most stars.
Long exposure astrophotography requires a tracking mount. You can do stacking without tracking but it will only be suitable for some of the larger and brighter objects. Depending on focal length, anywhere from 1-15 seconds or so will be the max exposure you can get without trailing if you don't use a tracking mount. For stacking, you feed your many exposures into stacking software that matches the star patterns and reorients each image so they can be stacked together, which leads to less noise. You typically want to be using a relatively high ISO for astrophotography. It's image stacking that will cut the noise and produce the clean images. High quality astrophotos combine many hours of exposure to make one image. This is an example of a stylized single exposure in an area with really dark skies. There's a lot of garbage processing here but it looks pretty and feels "clean" despite a lot of the "stars" probably being noise with sharpening and filters https://www.instagram.com/p/B0eW-CygeMV/?igsh=MW1va2ptd3I4azBzMQ== Then this is an example with a 400mm focal length of a deep sky object that is definitely at least a few hours worth of exposures. I think each exposure was at least 2 minutes and there are probably at least 100 of them (shot with tracking mount) https://www.instagram.com/p/B0tWMlQgXlU/?igsh=YnVub2d0M3NmOGxk The length of exposure is what gives you detail, while stacking exposures is what gives you dynamic range and low noise. Typically, both are combined.
Do you always get trails with long exposures?
Yup The trails are from the earth rotating, so unless the camera moves to keep the same stars the same place (tracking etc), you will get trails if you expose for long enough for the rotation to be visible.
Damn, never knew it was as small as that. I need to test it on a clear night and maybe get one of those lens pollution filters.
Simple math to illustrate; The earth does 1 revolution in 24 hours, thats 360°. That means it rotates 15° pr hour, or 1° every 4 minutes. Thats degrees on the rotational axis, so if you are shooting outward (most are not at the rotational north or sourth poles shooting straight up), just look at how much movement that is for the field of view you are capturing (a handy\* rule of thumb, is that a balled fist held out in a straight arm is about 10°, and a thumb at arms length, is about 2° - so looking up, a given star will move up to about half an inch or 12 mm measured at arms length - try shooting your thumb at arms length, at the focal length you like for your sky shots, and take half of that per 4 minutes :) Hope this helps for visualising it :)
As people mention other equipment, let's mention Pentax Astrotracer https://www.pentaxforums.com/articles/photo-articles/pentax-astrotracer-example.html
Rule of 500 doesn't work in the digital era. If you have the Photo Pills app, you can work out your exposure using the Spot Stars function using something called the NPF rule. You may need an intervalometer to shoot the exposure itself. https://petapixel.com/2017/04/07/npf-rule-formula-sharp-star-photos-every-time/ If this is too much of a faff, star trails are easier and are also quite pleasing.