# Highest ISO during Star Photography?



## tyqre

I've been reading some tutorials on star photography and they all say to use the highest ISO. When i tried to do this all i got was a very, very grainy image with my f4.0 10mm WA lens with my T2i. Any suggestions?


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## Heitz

yea, that's understandable.  You might consider using a tripod and a slow shutter speed with a less extreme ISO.  I'm not quite sure about the t2i specifically, but if you were really using the 'highest' ISO, it's probably much too high.  many SLRs perform quite well up to about 1600 (some even higher), but again, using a tripod and slow shutter speed might be best.


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## analog.universe

My suggestion is to be careful of what you read.  The highest ISO on any camera is pretty much never appropriate (a couple exceptions, but certainly not if quality is your goal).  I would say do some test shots to figure out how high your camera can go and still maintain an acceptable noise level, and then use that.  My camera maxes out at 12,800, but I shoot stars at 800, anything over that and the noise reduction becomes star reduction as well.  f/4.0 is certainly a limiting factor however...  the shots I've done were at 1.8, ISO 800, like 20 seconds (with a 28mm lens).


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## analog.universe

One more thought.... shooting at 10mm will allow you a longer shutter speed than my shots at 28, so you make up a little bit of the difference in aperture.


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## tyqre

I use a tripod by the way. I do have a f1.8 lense but its 50mm. I could try that. I guess it depends if i want a wider image or more light. But for the f4.0 would you say 800 is the max for a 40-60 second exposure or would you go lower (or higher)? Thanks for your help by the way.


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## analog.universe

The highest usable ISO is 100% dependant on the camera body, and I've not used yours so I'm not sure.  Some cameras will be totally fine at 1600, others will struggle at 400.  You can take some shots with the lens cap on to test yours out, see what kind of noise floor you end up with at each level.  Also, make sure you've enabled "long exposure noise reduction" in your camera (the manual will tell you where to find that option).  This noise reduction algorithm actually measures sensor noise immediately after taking the shot, so it's more effective than the purely mathematical reduction you can do in post.


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## tyqre

I turned on "long exposure noise reduction". I also see something called "high iso speed noise reduction" should i turn that on too? by the way i see that you are from Vermont, im form Mass


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## analog.universe

There is debate about whether "high iso speed noise reduction" does any better than noise reduction performed in post (assuming you shoot raw).  I leave mine off, because I like to be able to control the NR myself.  If you enable it, it takes a step out of your post processing, but leaves the NR settings up to the camera to decide.  If you shoot jpg, there is a definite advantage to the in camera reduction, but I wouldn't recommend shooting jpg, especially for star shots.

<3 New England


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## tyqre

of course i soot RAW  I guess ill turn it off and do some NR in lightroom. or something. And yes <3 NE live here all my life.


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## dakkon76

If you're on a tripod, why would you want to shoot anything but 100 ISO? Did the source you read say why you should be shooting at a higher ISO?


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## analog.universe

You're limited on shutter time because of star trails.  The earth is constantly turning, so the rule of thumb is you can get away with 600/focal length seconds, before the points start to become lines.


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## tyqre

that same source that said that i need to shoot at a higher iso also said that with crop sensors (which that t2i is) you should really go with 400/fl because of the magnification ultimately upping your focal length. So.. im going to try 40 seconds and see what happens. 100 may take too long since my aperture is 4.0 but 400-800 shouldn't do much harm anyway.


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## Robin Usagani

who are we shooting?  Kim Kardashian?  Justin Bieber?


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## analog.universe

tyqre said:


> that same source that said that i need to shoot at a higher iso also said that with crop sensors (which that t2i is) you should really go with 400/fl because of the magnification ultimately upping your focal length.



Right, I should've said "effective focal length".  Pretty much any time those sorts of rules get tossed around it's relative to 35mm format, so you need to adjust by whatever crop factor if you don't have a full frame sensor.  So technically that's 400 for Nikon, and 375 for Canon.


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## tyqre

astrophotography so..the stars i guess


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## tyqre

i guess that drops me down to 37.5 seconds :meh:
I just took this picture a few minutes ago with 800 ISO f4 30" 







just thought i would share (its cloudy out as you can see so i cant take many shots of the stars)


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## Garbz

Did you read the entire site where you read that you should use the Highest ISO? Because they are right, and your application is wrong. In star photography noise is your friend, your darling, the creator of your images, and you need to nurture it too to get even remotely decent results. 

If you're taking 1 single image of the sky the answer is to turn on long exposure NR and use the highest ISO you can bear for noise. On my camera that would be ISO200 for a long exposure of stars. The goal is to get the most brightness in the image without causing excessive noise.

If on the other hand you're trying to get deep and detailed images of stars then what you're after is the highest ISO your camera can produce by non artificial means. For me this is ISO1600, and not "Hi 1.0" which would be ISO3200 equivalent. The result is an image that looks so noisy you probably can't see the stars. Then you take 100 more, and make sure noise reduction is off. 

The key to getting deep detailed images of the cosmos is to use the statistical nature of noise to capture photons that would otherwise not be recorded. When you take High ISO shots you end up with a lot of noise, but when you STACK high ISO shots together and take the average value the noise disappears, and what is left is the anomalies in the statistics from the stray photons hitting the sensor. This will show you a starfield you would never have thought was recordable. This is how amateur astro photographers are able to take photos of things like the Andromeda galaxy from their backyards. The best image I ever saw was recorded over a period of about 1 week. The photographer took ~20 images several minutes each every night and stacked the result. 

If you want to know more about the method head over to Deep Sky Image Stacker website. The software is free.


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## McNugget801

Stars will start moving after 30 seconds, so unless your going to do some trails use a high ISO and an open aperture.

ISO2000 F2.8 10mm Fisheye



Milky by Summit42, on Flickr


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## tyqre

Do what your saying is use a high ISO, wide aperture,take a lot of pictures and stack them together?
and by stacking you mean taking many pictures of the same ISO/aperture/whatever and combining the in a program (Im using a mac so i cant use Deep Star Stacker but do you have any suggestions?) or taking many different exposures and combining them? And by the highest ISO do you mean everything below HI? My camera goes up to 6400 without being on Hi. 

Sorry for all the questions


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## DiskoJoe

iso 100 for about 30 - 40 minutes.


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## tyqre

DiskoJoe said:


> iso 100 for about 30 - 40 minutes.



Yes but after 30 seconds the stars will stark to trail - which is what i do not want in this case.


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## DiskoJoe

tyqre said:


> DiskoJoe said:
> 
> 
> 
> iso 100 for about 30 - 40 minutes.
> 
> 
> 
> 
> Yes but after 30 seconds the stars will stark to trail - which is what i do not want in this case.
Click to expand...


ehh


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## McNugget801

DiskoJoe said:


> iso 100 for about 30 - 40 minutes.


 yeah, horrible settings for a star trail.


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## tyqre

what im really trying to do is get photos like this 

Crater Lake under the Stars | Flickr - Photo Sharing!

From what i know what stacking is i dont think he used stacking for this shot. Although i am probably wrong.


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## dmtx

> iso 100 for about 30 - 40 minutes.



Make sure your camera's sensor will handle a 30+ min exposure.  I know of overheating issues with some models.

On the "Crater Lake under the Stars" image, I think that this was multi. images taken to capture the sky, then the land, etc. and blended together in an editor.


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## tyqre

dmtx said:


> iso 100 for about 30 - 40 minutes.
> 
> 
> 
> 
> Make sure your camera's sensor will handle a 30+ min exposure.  I know of overheating issues with some models.
> 
> On the "Crater Lake under the Stars" image, I think that this was multi. images taken to capture the sky, then the land, etc. and blended together in an editor.
Click to expand...

oh, so its like an HDR image? Do you think he did image stacking for the sky?

Another Question, What are the differences between Light, Dark and Bias images?


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## tyqre

McNugget801 said:


> Stars will start moving after 30 seconds, so unless your going to do some trails use a high ISO and an open aperture.
> 
> ISO2000 F2.8 10mm Fisheye
> 
> 
> 
> 
> Milky by Summit42, on Flickr




to make that image did the person do image stacking or was this 1 picture?


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## Josh66

tyqre said:


> dmtx said:
> 
> 
> 
> 
> 
> 
> iso 100 for about 30 - 40 minutes.
> 
> 
> 
> 
> Make sure your camera's sensor will handle a 30+ min exposure.  I know of overheating issues with some models.
> 
> On the "Crater Lake under the Stars" image, I think that this was multi. images taken to capture the sky, then the land, etc. and blended together in an editor.
> 
> Click to expand...
> 
> oh, so its like an HDR image? Do you think he did image stacking for the sky?
> 
> Another Question, What are the differences between Light, Dark and Bias images?
Click to expand...


It says right in the description.  It's a 9 image panorama.  5 for the sky, 4 for the landscape.  (So, no - no stacking.  Just stitching.)


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## tyqre

oh ok thanks.


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## kundalini

Garbz said:


> Did you read the entire site where you read that you should use the Highest ISO? Because they are right, and your application is wrong. In star photography noise is your friend, your darling, the creator of your images, and you need to nurture it too to get even remotely decent results.
> 
> If you're taking 1 single image of the sky the answer is to turn on long exposure NR and use the highest ISO you can bear for noise. On my camera that would be ISO200 for a long exposure of stars. The goal is to get the most brightness in the image without causing excessive noise.
> 
> If on the other hand you're trying to get deep and detailed images of stars then what you're after is the highest ISO your camera can produce by non artificial means. For me this is ISO1600, and not "Hi 1.0" which would be ISO3200 equivalent. The result is an image that looks so noisy you probably can't see the stars. Then you take 100 more, and make sure noise reduction is off.
> 
> The key to getting deep detailed images of the cosmos is to use the statistical nature of noise to capture photons that would otherwise not be recorded. When you take High ISO shots you end up with a lot of noise, but when you STACK high ISO shots together and take the average value the noise disappears, and what is left is the anomalies in the statistics from the stray photons hitting the sensor. This will show you a starfield you would never have thought was recordable. This is how amateur astro photographers are able to take photos of things like the Andromeda galaxy from their backyards. The best image I ever saw was recorded over a period of about 1 week. The photographer took ~20 images several minutes each every night and stacked the result.
> 
> If you want to know more about the method head over to Deep Sky Image Stacker website. The software is free.


Hmmmm, I see nobody else has thanked you, so I certainly shall.  Thanks for an insightful reply.  I will look into the Deep Sky Image Stacker website.


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## Josh66

tyqre said:


> oh ok thanks.


He must have very dark and clear skies up there in Oregon too...


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## tyqre

i forgot to thank him amongst all the comotion!


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## tyqre

Yea, he was on top of Mount Hood to top it all off.


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## McNugget801

tyqre said:


> McNugget801 said:
> 
> 
> 
> Stars will start moving after 30 seconds, so unless your going to do some trails use a high ISO and an open aperture.
> 
> ISO2000 F2.8 10mm Fisheye
> 
> 
> 
> 
> Milky by Summit42, on Flickr
> 
> 
> 
> 
> 
> to make that image did the person do image stacking or was this 1 picture?
Click to expand...


Its my photo
One 30second exposure
10mm fisheye
f2.8 
ISO 2000 
with a bit of noise reduction done in lightroom.



tyqre said:


> Yea, he was on top of Mount Hood to top it all off.


actually that's the rim of creator lake


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## molested_cow

In my experience, ISO is secondary. Shutter speed the primary element that you need to decide.

What kind of star shots are you trying to get? Star trails or just the clear milky way?

Then, what lens are you using? 20mm? 35mm? 300mm? Cropped or full frame?

The reason why these matters is because it will determine how much the stars move in the photo. For example, using a 20mm on full frame, I know that I cannot go above 30sec.

So after getting that straight, I can then play with ISO and aperture. If I want the foreground (landscape silhouette or objects like trees ) to be in the shot, I want lower aperture setting, that means I need to push ISO higher. If everything in the frame is far away, I can afford to have higher aperture and therefore lower ISO.

Generally speaking, I can get away with a nice exposure with the following set up.
20mm full frame at F5, 30sec, ISO 1600~2500


For light trails, I haven't gotten much chance to do it since I got my digital. So far I've been doing 10min exposures and stack them up. It's a tricky balance of noise. If you so shorter exposures, you need higher ISO or aperture to get the same exposure. That may mean more noise. If you do longer exposures, you can use lower ISO but you will get more of those colored specs (not sure what they are called). I am still learning it.

Also, there is no absolute setting. It depends on the environment condition and time of the day as well. It's all trial and error.


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## tyqre

McNugget801 said:
			
		

> Its my photo
> One 30second exposure
> 10mm fisheye
> f2.8
> ISO 2000
> with a bit of noise reduction done in lightroom.
> 
> actually that's the rim of creator lake



Oh, one exposure? Thanks that clears some things up.


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## tyqre

molested_cow said:
			
		

> In my experience, ISO is secondary. Shutter speed the primary element that you need to decide.
> 
> What kind of star shots are you trying to get? Star trails or just the clear milky way?
> 
> Then, what lens are you using? 20mm? 35mm? 300mm? Cropped or full frame?
> 
> The reason why these matters is because it will determine how much the stars move in the photo. For example, using a 20mm on full frame, I know that I cannot go above 30sec.
> 
> So after getting that straight, I can then play with ISO and aperture. If I want the foreground (landscape silhouette or objects like trees ) to be in the shot, I want lower aperture setting, that means I need to push ISO higher. If everything in the frame is far away, I can afford to have higher aperture and therefore lower ISO.
> 
> Generally speaking, I can get away with a nice exposure with the following set up.
> 20mm full frame at F5, 30sec, ISO 1600~2500
> 
> For light trails, I haven't gotten much chance to do it since I got my digital. So far I've been doing 10min exposures and stack them up. It's a tricky balance of noise. If you so shorter exposures, you need higher ISO or aperture to get the same exposure. That may mean more noise. If you do longer exposures, you can use lower ISO but you will get more of those colored specs (not sure what they are called). I am still learning it.
> 
> Also, there is no absolute setting. It depends on the environment condition and time of the day as well. It's all trial and error.



Ok thank you, I'll take that into consideration, I'm using a crop sensor at 10mm with max aperture of f4. I'm not trying to get star trails, just detailed images of the night sky. So I should shorter exposures with open aperture and a high ISo, or it depends on conditions. I guess it depends on what's going on because that post above (which is awesome btw) had a 30sec exposure but if i used those settings outside my house the image would be really washed out.


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## Garbz

There's plenty of software out there for image stacking. I've seen several for mac as well but as I am a windows user you'll need to use the almighty Google to find some. Some software is free, other software is cheap so look around.

If you're after a single exposure with crystal clear skies and lake as above then stacking is one way to do it unless you have a camera with a mad low noise. I haven't seen Sw1tch post here yet but he's created some beautiful results with a D700 at high ISO and a 24mm f/1.4 but who has the money for that stuff right ? 

I resort to stacking. And if you have a D700 and 24mm f/1.4 that will make stacking even better. Here's a result on a D200 with a kit lens, a combination known not for image quality, and actually known for pretty damn high noise: http://www.garbz.com/stars.jpg

The result is made up of 80 30 second exposures taken over a one hour period. Deep Sky Image Stacker's algorithm also takes into account additional frames for it's process so there were a further 30 frame shot a day later with the lens cap on in same settings. The resulting images were loaded into the software twice. Once star tracking was enabled which lined up all the images to get one final frame and once it was disabled which produced a noise free foreground (because I was too drunk to remember to crank out a 15min frame for the foreground) The resulting two images were combined in post.

The process is a bit of a rigmarole but the results can be very worth it. Mine have been getting better each time. A prime lens really helps and if you don't have one then you will need to come up with a method of eliminating distortion. The above image I took had distortion corrected in Lightroom and then the TIFs were stacked. However the better process would be to use a distortion free lens to begin with and use RAWs in Deep Sky Stacker due to the different ways the program treats RAW files from conventional RAW processors. 

All in all, it's a process worth learning: http://ghonis2.ho8.com/100408horse.jpg here is an example shot by a guru using what can only be referred to as a cheap arse DSLR a Canon 350D, made of 30x 6min shots at ISO1600. His website is a throwback to the days of Geocities, and I'm surprised he doesn't use the old <BLINK> tag, ASTROPHOTOGRAPHY & DIGITAL IMAGING by Gary Honis but the result speak for themselves. The method does wonders for noisy cameras.


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## tyqre

Garbz said:


> There's plenty of software out there for image stacking. I've seen several for mac as well but as I am a windows user you'll need to use the almighty Google to find some. Some software is free, other software is cheap so look around.
> 
> If you're after a single exposure with crystal clear skies and lake as above then stacking is one way to do it unless you have a camera with a mad low noise. I haven't seen Sw1tch post here yet but he's created some beautiful results with a D700 at high ISO and a 24mm f/1.4 but who has the money for that stuff right ?
> 
> I resort to stacking. And if you have a D700 and 24mm f/1.4 that will make stacking even better. Here's a result on a D200 with a kit lens, a combination known not for image quality, and actually known for pretty damn high noise: http://www.garbz.com/stars.jpg
> 
> The result is made up of 80 30 second exposures taken over a one hour period. Deep Sky Image Stacker's algorithm also takes into account additional frames for it's process so there were a further 30 frame shot a day later with the lens cap on in same settings. The resulting images were loaded into the software twice. Once star tracking was enabled which lined up all the images to get one final frame and once it was disabled which produced a noise free foreground (because I was too drunk to remember to crank out a 15min frame for the foreground) The resulting two images were combined in post.
> 
> The process is a bit of a rigmarole but the results can be very worth it. Mine have been getting better each time. A prime lens really helps and if you don't have one then you will need to come up with a method of eliminating distortion. The above image I took had distortion corrected in Lightroom and then the TIFs were stacked. However the better process would be to use a distortion free lens to begin with and use RAWs in Deep Sky Stacker due to the different ways the program treats RAW files from conventional RAW processors.
> 
> All in all, it's a process worth learning: http://ghonis2.ho8.com/100408horse.jpg here is an example shot by a guru using what can only be referred to as a cheap arse DSLR a Canon 350D, made of 30x 6min shots at ISO1600. His website is a throwback to the days of Geocities, and I'm surprised he doesn't use the old <BLINK> tag, ASTROPHOTOGRAPHY & DIGITAL IMAGING by Gary Honis but the result speak for themselves. The method does wonders for noisy cameras.



Thanks for the tips. You sure do like those walls of text


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## tyqre

im just a little confused on what stacking actually is. Correct me if im wrong = Stacking is taking a bunch of the same photo all at the same time and combining them in a stacking program.


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## Patrice

tyqre said:


> You sure do like those walls of text



Sometimes good information requires more than a dozen words in a barely coherent sentence. Garbz has posted some good information leading you in the right direction.

Stacking is the combining of a number of images taken over a period of time. (You can't really take 40 or more images at the same time unless you happen to have 40 or more cameras.) The dark frames referred to are images of similar length exposure take at various times during the imaging session. These dark frame images are taken with the lens cap on. The purpose is to map out the irregularities of your sensor and then correct for them during the stacking process. 

Look up 'Keith's image stacker'. It's a free stacker for Macs. You'll have to spend a bit of time doing some attentive reading and some practice before you are handy with this software.

Look on various astronomy websites and forums, many have a beginner astrophotography section.


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## tyqre

ok thanks.


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## Garbz

tyqre said:


> Thanks for the tips. You sure do like those walls of text



I don't read the forum every 5 minutes, so I miss quite a bit and have to reply in bulk 



tyqre said:


> im just a little confused on what stacking actually is. Correct me if im wrong = Stacking is taking a bunch of the same photo all at the same time and combining them in a stacking program.



Stacking is a general term of combining images for certain post processing events. e.g. Exposure stacking combines images with different exposure to generate higher dynamic range, focus stacking combines images with different focal points to expand the depth of field, and this is just yet another form. All that changes is the algorithm.

If you're in an area with light pollution for instance one of the programs I've seen on the net stacks images together and selects the MAXIMUM pixel value in each for the final pixels. For star trails this has the advantage of being able to create trails of unlimited length without increasing the brightness of the sky.So you get results like this: http://farm2.static.flickr.com/1353/773160897_fae20200db_b.jpg which has a startrail length of 90 minutes, but in a light polluted city with an exposure of about 1minute. A single 90min exposure would have been nearly white in this case.


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## tyqre

> f you're in an area with light pollution for instance one of the programs I've seen on the net stacks images together and selects the MAXIMUM pixel value in each for the final pixels. For star trails this has the advantage of being able to create trails of unlimited length without increasing the brightness of the sky.So you get results like this: http://farm2.static.flickr.com/1353/...e20200db_b.jpg which has a startrail length of 90 minutes, but in a light polluted city with an exposure of about 1minute. A single 90min exposure would have been nearly white in this case.



I am sorry i keep asking the same question over and over again but.. what your saying is that if i want to get a picutre where you can see the milky way from my house that look like this http://viewzone2.com/milkyway2.jpg(i dont live in a city but i live in the suburbs 15 miles away)  I would have to take multiple 37 sec (maximum for my setup without trailing) exposures and combine then using the stacking software of my choice... Right?


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## Garbz

That is correct. Or you invest in a Camera with ludicrously low noise and an expensive wide aperture lens.

Although don't confuse this with the part of my text you have quoted. What I described above about stacking to a maximum pixel value will not make stars more visible, it simply ensures that the stars you can see can be trailed without blowing out the sky. 

If you can't see the milky way when you look up then no amount of camera work can help you.


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## Compaq

I'm confused. Stacking images would require some mount that follows the earth's rotation, no? 80 30 seconds exposures would take 40 minutes, AT BEST, which means stuff mas moved pretty far.

Or am I missing something extremely obvious, here?


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## McNugget801

Ok... 
There is no standard settings for shooting at night. Depending on ambient light you will need to adjust your exposure, F-stop, and ISO to meet the needs of the scene your trying to capture.

Long story short... you need to get out there and figure out what works for different scenarios.

High ISO, Wide Aperture, and Longer Exposure equal more light and more stars.
As mentioned in previous posts shooting an exposure longer then 30seconds (this fluxuate will depending on focal length) you will capture star movement. Also if you cant see the milky way with your own eyes.. you not going to get a good shot of it. 


Here are a few examples of images I have taken.

30sec F2.8 11mm ISO3200



Light by Summit42, on Flickr

30sec f2.8  ISO6400



Uintas Camp 7.7.2010 by Summit42, on Flickr


30sec F5.6 ISO800



North Temple Wash 3.26.2010 by Summit42, on Flickr


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## Garbz

McNugget those are fantastic landscapes, but quite in the realm of the second method I was talking about: Good Camera + Fast Glass.



Compaq said:


> Or am I missing something extremely obvious, here?



Yep, image processing. When I hit the big green go button in my stacking program the first two steps are 1) identifying stars, 2) aligning images :lmao:

Hence to make the image I posted earlier I had to stack twice with alignment on and off and combine in photoshop because I didn't want my foreground to be a rotational blur.


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## radiorickm

analog.universe said:


> One more thought.... shooting at 10mm will allow you a longer shutter speed than my shots at 28, so you make up a little bit of the difference in aperture.



Can you please explain your thinking in this comment? How will focal legnth alter the exposure? The only thing I can think of is if you are not using a constant aperature zoom and zooming out give an extra stop?


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## McNugget801

radiorickm said:


> analog.universe said:
> 
> 
> 
> One more thought.... shooting at 10mm will allow you a longer shutter speed than my shots at 28, so you make up a little bit of the difference in aperture.
> 
> 
> 
> 
> Can you please explain your thinking in this comment? How will focal legnth alter the exposure? The only thing I can think of is if you are not using a constant aperature zoom and zooming out give an extra stop?
Click to expand...


It really doesn't effect the exposure. The wider you shoot the smaller the stars will be hence movement wont be as visible when shooting at 10mm compared to 200mm.
Another factor with star movement that had yet to be discuses is the position of the sky that your shooting. When shooting on the northern hemisphere stars in the south move faster then stars in the north.  Here another example shot of mine taken with my 10mm fisheye with a 167° viewing angle. This is a series of stacked images to create the the star trails...this is NOT the same stacking method as mentioned in previous posts. 
 Anyways... notice the star movement is longer on the southern portion of the image. The cloudy area in the center right is the milky way moving across the sky in the during the 35min 




Starry Night in Escalante by Summit42, on Flickr

here is a single exposure form the above stack for comparison



Camp by Summit42, on Flickr


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