Intro to image stacking: Step-by-step

[A.S.I.G.N. Observatory]

Like a lot of astrophotographers, I get repeated questions on how to do things that although may seem simple, I have to remind myself that they were once beyond me...

So last night, I sat up all night and stacked some images in Deep Sky Stacker, taking screenshots all the way and writing down what I did as I went.

Hopefully this can answer a lot of questions and get the new blood in the game well on their way to adding to the richness of images proliferating amateur astronomy.

http://www.asignobservatory.com/index.php?option=com_content&view=article&id=84&Itemid=125

Have a crack, enjoy and let's see what you new folks can do!!! YEEEHHARRR!

Baz.:cool:

[Adrena1in]

Thanks for taking the time to do this Baz. I've used DSS many times now, so I know how to stack images without really thinking twice, but I've not really got much of an idea what all the options and settings do, so hopefully your guide will made good reading for someone like me, just as much as for a complete beginner.

[A.S.I.G.N. Observatory]

No worries mate, I hope it helps you out...

[jgrussell]

Filed away for the day I get to an area without so much light pollution...

[VIGER]

Very generous of you.

Cheers

Michel

[hollis_f]

Great summary. I can't wait to try my 7D at ISO6400. All I need is for this damn rain to go away.

[Harm]

Thank you for an excellent thread - this should be made a sticky

[Jeff]

Thanks so much! I restacked an M31 image from a few months ago and WOW! What a difference.

[A.S.I.G.N. Observatory]

My extreme pleasure folks! Now let's see you do your stuff!!!

Cmon Jeff...where is it!!!???


Baz.

[Jeff]

I'm glad I hung on to the raw files from a couple of months ago. A stack of 50 59sec images at f/2.8, along with 10 darks.

Before:
http://www.seivertfamily.com/POTN/M31_A.jpg

After:
http://www.seivertfamily.com/POTN/M31_B.jpg

[hollis_f]

I'm glad I hung on to the raw files from a couple of months ago. A stack of 50 59sec images at f/2.8, along with 10 darks.



OK, that's exactly what I want to do. And I'll be happy if it's half as good. Just two questions -

What focal length? I know M31 is bigger than what you can see if the naked eye or bins, but I'd assumed you needed something reasonably long. But the amount of trailing you've got on 59 second exposures looks like it must have been fairly wide.

Second question? What's the best way to get a good focus - AF on a bright star; AF on a distant terrestrial object; MF (with liveview)?

[VIGER]

Good stuff Jeff

Question:

50 59sec images at f/2.8 You mean 50 X 59 sec that's almost an hour.

[Harm]

correct...

[Adrena1in]

What focal length? I know M31 is bigger than what you can see if the naked eye or bins, but I'd assumed you needed something reasonably long.
200mm to 500mm I'd say. Much longer and it won't fit in the frame.

But the amount of trailing you've got on 59 second exposures looks like it must have been fairly wide.
With a good tracking mount you should be able to go as long as possible and get little or no trailing. With no mount you'd get trails in about 3 seconds at 200mm+

Second question? What's the best way to get a good focus - AF on a bright star; AF on a distant terrestrial object; MF (with liveview)?
Good luck using AF on a bright star. I always use MF for astrophotography, even on the moon.

[Jeff]

Yes to pretty much all of it. 50 individual 59sec images. It was taken with a 50D & Sigma 70-200 lens at 200mm and f/2.8. The whole thing was piggybacked on a 10" LX200 GPS for tracking. Not polar mode, so there is a little field rotation. I cropped off about 10% of the edges. Manually focused via live view (10x) on a bright star nearby then moved over to M31.


Good stuff Jeff

Question:

You mean 50 X 59 sec that's almost an hour.

200mm to 500mm I'd say. Much longer and it won't fit in the frame.


With a good tracking mount you should be able to go as long as possible and get little or no trailing. With no mount you'd get trails in about 3 seconds at 200mm+


Good luck using AF on a bright star. I always use MF for astrophotography, even on the moon.

[hollis_f]

With a good tracking mount

D'oh! Yes, didn't think of that.

[Michael_B]

Thanks alot Barry..You just inspired me to go out and try this...I have done star trails with Star Max, but never tried this..I will post my result!

[Michael_B]

Here it is..DSS rocks! Oh, I know there are some things I don't see...maybe too much color saturation, some blur, the tree!, I was off center, but hey not bad for my FIRST shot!

[Michael_B]

How do you get rid of the angled edges that result from the stacked image? Also, on the recommended settings tab, the "use median combination method" choice is not there..and should I add some black frames to get the hazy grey out?

[chris.bailey]

Awesome tutorial Baz. Should be a sticky.

You do pretty much the same as I do. A few additions though.

On some images it will be necessary to play with the star detection threshold to get enough stars recognised to stack on.

On the settings>light tab it can sometimes be worth playing with the RGB Channels BVackground Calibration setting to get the colours right.

If you have enough light frames, Kappa Sigma stackign can give marginally better results.

It is worth deselecting any frames that have FWHM, Sky Background or Starts detected significantly different to the bulk of the frames.

DSS is a great programme that gets better and better.

[Madweasel]

How do you get rid of the angled edges that result from the stacked image?
They result from images that are taken on a fixed tripod, rather than a driven mount. It is more apparent in wideangle shots and is due to the projection of a rectilinear lens, which effectively magnifies the corners of the image to keep straight lines straight. This means that the images do not quite match each other, the main difference being towards the corners.

There are two solutions: shoot on a driven mount or use a fisheye lens. I believe there may be stacking programs that will apply the necessary distortion between frames to make them match, but DSS doesn't do that.

[Michael_B]

Yeah, on one of my images I just cropped it out, without losing too much of the image.

[MintMark]

If you don't want the angled edges you can set the output to intersection instead of mosaic. Then you'll just get the largest rectangular area that is present in all the frames.

[Harm]

I've gotten admin to add this to a new post (you'll see the sticky at the top) about "How to" techniques...

Hopefully you star wizards can add more to them, as they are great reads and insights on how to do what you guys do best.

[VIGER]

can add more to th

Sounds like a plan. Having PDF file format for download would be good also no ?

[Jeff]

Just to keep this thread alive lets talk about stacking "dark frames" for a minute.
A dark frame is an image taken at the same settings - ISO, length of time, temperature, etc - as the light frames except not allowing ANY light to reach the sensor.

My understanding is that DSS will take all of your dark frames, combine them into one "master dark" then subtract that from each of the light frames, thus reducing noise. Is this right?

My questions are:
Is there an minimum, maximum, optimum, or some ratio of dark frames needed? I think I read a 3:1 light to dark ratio. Thus 45 lights should have about 15 darks?
Would the number of darks vary based on target, temperature, ISO or any other settings?

[Madweasel]

It's just an averaging thing, so the more you take, the better. But noise reduction goes as the square root of the number, so 4 is twice as good as 2, but you'd need to use 16 to get twice as good as 4, at least roughly speaking.

[MintMark]

One thing that made me wonder... for light frames DSS recommends averaging or kappa sigma (for many light frames). For dark frames it recommends median to combine them. Why is that?

I'm also a bit confused by the elimination of hot pixels. There seem to be options for removing them from the light frames and from the dark frames, but I thought subtracting the dark frames with the hot pixels from the light frames with the hot pixels was how you got rid of the hot pixels! Maybe in DSS the dark frame subtraction is about subtracting fixed noise and the hot pixels are treated separately.

And another thing... I was doing some heavy stretching the other day (with the images!) and I think I saw banding patterns coming through that were in the master dark but not in the individual darks or lights, so it affected the stack. I need to investigate that some more...

[SteveInNZ]

The median is used for the dark frame to cater for the occasional wild value. If you were to take a very large number of dark frames, the noise would average out to a particular value. In reality we tend to not take many dark frames so using the median means that if we get one value that's wildly different it won't throw the result out. For example, if we were getting 2, 3, 1, 3, 2, 1, 1, 2, etc and then got one of 236 then the average would be 29 while the median would be 2.
The median is a more valid representation of the background noise.

In the case of a light frame we want that number included (or at least considered) as it's more likely to be valid. For example stars dancing around in air currents.

Hot pixels aren't quite as straight forward as we generally assume. They can show themselves in a variety of ways. eg being overly sensitive so in the dark frame they are dark but it only takes a little light for them to saturate.

Steve.

[Jon Foster]

I've been waiting all summer to play with this stuff. Every time I have the time to get outside the weather is terrible. And I haven't had the time to get away from the city and it's light pollution... I'm getting frustrated!

Jon.

[MintMark]

Maybe when the clocks change you'll have more time in the darker evenings? That's what I'm hoping for anyway. Still need the weather to co-operate though.

[weeatmice]

Heres my first try stacking pics of Andromeda. Actually a bit of a victory for me as I was never able to find it naked eye or with bins, however it was plain as day on the cameras LCD in a test shot.

Technical info:
85mm f1.8 on full frame @ f1.8, ISO 3200, tripod and a few seconds per exposure. 25 lights, 8 darks, 15 bias frames stacked using DSS. Spent a long time tweaking levels in DSS, then corrected vignetting a bit in ACR.

http://farm3.static.flickr.com/2558/4108996939_24dec0c6a2_b.jpg

[skygod44]

Thanks Baz for the excellent write-up and thread...I'm downloading DSS as I type this, and hope to get some shots as soon as I can locate where anything is up there!
:D

[mpistone]

Very nice tutorial, thanks!

[A.S.I.G.N. Observatory]

Most welcome guys.

Baz

[Adrena1in]

Technical info:
85mm f1.8 on full frame @ f1.8, ISO 3200, tripod and a few seconds per exposure. 25 lights, 8 darks, 15 bias frames stacked using DSS.

Damn!! That's a lovely image there. I do love widefields and you've captured some excellent data. Great lens, and great result considering you weren't tracking. :D

[supraintendent]

This question isn't exactly related to astro photography, but it's about DSS:

Would it be possible to use DSS to stack a bunch of non-celestial images (for example, a street scene at night) and if so, would I have to use different settings from what is mentioned in the tutorial?

The idea is that I would like to do a really long exposure, maybe 8-12 hours or longer, (days even?) but I'd like to figure out an alternative to leaving the shutter open for that long. (I don't necessarily mean that the sum total of all the exposure times would equal 8-12 hours, but that the shots would be taken over an 8-12 hour period...) I thought maybe stacking in DSS would be one solution.

Any thoughts?

[mpistone]

Supraintendent:
I'm still new to DSS but I tried stacking 'terrestrial' images and it sorta bonked out during the registration.
What are you hoping to do? Unless you're dealing with stars I don't think DSS has much to offer (but I could be wrong!). I'd use layers in photoshop or gimp to combine whatever is changing (sun/shadow positions, people, etc).

[weeatmice]

Yeah, DSS looks for stars, so it may have problems unless there are at least some in the image. You might be able to get Photoshops Photomerge or HDR tools to align the images for you however.

[supraintendent]

Ok, thanks for the info. I'll try a test of concept in Photoshop or HDR tools and see how it comes out. (I just thought maybe DSS would give me some other options, but it sounds like it's not what I'm looking for...) After reading this thread though, I'll have to give DSS a go on some stars sometime!

[theague]

Another thing to try :)

[A.S.I.G.N. Observatory]

Back on topic...has anyone here now gone out and tried image stacking, based on my tutorial? How did you go? Has anyone got a picture as a result of learning from this tutorial?

Baz.

[theague]

I'd give it a try but I live in a very light polluted area so to get the Milky Way or any other objects are probably beyond what I can do :(

[mpistone]

Hey Barry, even without having posted my results I guarantee lots of us are glad to have the tutorial!
Here's the first one I did (weather's been spotty since then). This was with a fisheye in the desert, and the light pollution was pretty evident.
I also found that if I used all ~30 shots I have available the image came out less sharp than when I used just the first 15 (around the sides the stars seemed to be stretched a bit). Does the fisheye being not-rectilinear make that happen? Any other ideas?

http://farm3.static.flickr.com/2685/4385856799_440297e764.jpg

[A.S.I.G.N. Observatory]

Hi Matt, I would say that it becomes more difficult when you include a foreground object, as the stars advance each frame but the foreground remains static. DSS stacks and aligns the STARS in the image, so eventually the foreground will suffer from motion-blur.

Baz.

[joeseph]

Back on topic...has anyone here now gone out and tried image stacking, based on my tutorial? How did you go? Has anyone got a picture as a result of learning from this tutorial?

Baz.
not yet - I'm still kicking myself for not having a go at some astro shots last easter when I was in a fairly remote part down south with very clear skies. Hoping to get back there this Easter so will post anything worth looking at...

p.s. thanks for taking the time to write the tutorial!

[A.S.I.G.N. Observatory]

not yet - I'm still kicking myself for not having a go at some astro shots last easter when I was in a fairly remote part down south with very clear skies. Hoping to get back there this Easter so will post anything worth looking at...

p.s. thanks for taking the time to write the tutorial!
Hey my pleasure mate! Make sure you post your result back here mate so we can all see how you are going!

Clear and dark skies to you mate!

Baz.:cool:

[Harm]

Can you set up a tripod with camera, 30 second shot, burst mode, then using a remote shutter, lock it in and it will take say 1-2 hrs worth of photos come back and hey presto you can (assuming you got your settings right and some creature of the dark abyss hasn't knocked over the camera) tart it up in DSS?

[mpistone]

Can you set up a tripod with camera, 30 second shot, burst mode, then using a remote shutter, lock it in and it will take say 1-2 hrs worth of photos come back and hey presto you can (assuming you got your settings right and some creature of the dark abyss hasn't knocked over the camera) tart it up in DSS?

Exactly! At 30 seconds you might see too much star blurring (depends on your focal length), so take some test shots and zoom in on the lcd to check before you leave for an hour, but yeah that's the idea.

[Harm]

Ahhhh, gotcha...

So shots that are long enough to allow the light of the stars in, but not to blur them at all...bingo.

I'll deffo have to test it out some time then...

[mpistone]

And I believe there's something fundamentally better about longer exposures (something about picking up the more faint objects) so I'd think it's best to push it as long as you can without stretching the stars out.

[Jonathan.kichizi]

Forgive me if this is a stupid question, but I am new to all of this. Can I use DSS to create a star trails picture? In other words, can DSS stack images so that the horizon remains fixed and the stars purposefully blur but I still get the advantages of noise reduction, shorter sub exposure times, etc?

[Jeff]

Ahhhh, gotcha...

So shots that are long enough to allow the light of the stars in, but not to blur them at all...bingo.

I'll deffo have to test it out some time then...

The individual shots may not show movement if the exposure is short enough but the overall image will because the tripod is not tracking the stars as they move across the sky.


Forgive me if this is a stupid question, but I am new to all of this. Can I use DSS to create a star trails picture? In other words, can DSS stack images so that the horizon remains fixed and the stars purposefully blur but I still get the advantages of noise reduction, shorter sub exposure times, etc?

I don't know if DSS will do it or not but this software does an amazing job at it:
http://www.startrails.de/html/software.html

Sample:
http://www.seivertfamily.com/POTN/StarTrails2_177k.jpg

[Vladimer]

Thats a great write up man! I've wanted to try this for a long time but always skipped over it thinking my results would be a flop.

So if i understand correctly you managed to get that final image using just a 400D and a standard kit lens on a tripod? I know its written there but i just want to be sure before i run out with my camera thinking im going to get more then star trails because thats a pretty stunning picture.

Oh and when you shoot the stars do you just focus to infinity? or do you still have to try and MF on the stars

Thanks :)

[Jeff]

I have a question:
I'd like to accumulate images over several different nights and combine them. Assuming the temperature is different each night I'd take a set of darks for each night. Does it matter that the darks will be different or do you just let them all average into one master dark regarless of the different temps at which they were shot and then subtract that dark from each nights' images? We'll assume all of the images will be shot at the same exposure settings. How much of a temp diff would matter?

[A.S.I.G.N. Observatory]

I have a question:
I'd like to accumulate images over several different nights and combine them. Assuming the temperature is different each night I'd take a set of darks for each night. Does it matter that the darks will be different or do you just let them all average into one master dark regarless of the different temps at which they were shot and then subtract that dark from each nights' images? We'll assume all of the images will be shot at the same exposure settings. How much of a temp diff would matter?
I have quite often taken photos of a deep space nebula over a number of nights to accumulate a better signal to noise ratio. I usually take all my darks on a night in between when there are clouds or a moon so that I get the most out of my clear nights.

Sometimes I shoot the lights all night until I get tired, switch off the mount and go to bed while the camera takes it's darks.

Baz.

[Blazin]

So I'm preparing to go to some of the darkest parts of the Eastern US.. I want to do this right.

At my disposal will be a tripod, 5dII, 16-35mm f/2.8, intervalometer. My plan is as follows:

Get a stack for star trails with some interesting foreground, but then go for a pure astro shot, hoping to stack based on this tutorial. I know settings will vary, but my thought was 16mm, f/2.8, ISO as low as possible, and exposures as long as needed to bring out the stars but not cause trailing due to my inability to track.

Will this mentality be sufficient to obtain some shots as seen above? For Reference I'm headed to the following:

http://www.jshine.net/astronomy/dark_sky/index.php?lat=43.74332071724287&lng=-74.586181640625&zoom=9&pollution=true&selected_id=1

Either Pharoah Lake or Raquette Lake.. obviously one is less susceptible to light pollution than the other, but I'm coming from Boston.. either will be a great improvement.

Thanks!

[Madweasel]

It should work fine. You might find if you try to stack too many that the projection of the lens will spoil the alignment of stars towards the edges when your mount is not driven.

[NukeGM]

This is my 2nd shot I have tried with DSS so I am quite new to this. I used your tutorial for this shot here. This is just light frames that I used, about 40 of them no darks were used. I can't seem to get color back into the pic? Is there something I am doing wrong?

I sent the TIFF file to another member that is helping me also and he is finding the same thing out about not much color being able to be brought back into the shot. The shot has light pollution in it I know but for practice this was just in the backyard once I get better then I will drive out of town to gets some shots. Anyone has any ideas as the color issue?

[Atsumi]

I can't get mine to save with the settings. :/ Any ideas why the .TIFF I save from my stacked image just saves as a normal one shot picture?

[Atsumi]

Here's my first attempt. I got something (other than the focus, LOL) wrong.

This was also taken off my back deck, so I might find a better spot later tonight/tomorrow.

http://farm5.static.flickr.com/4094/4781387450_3df4946cfa_b.jpg
Settings: ISO800, 13 seconds each, 12 shots, 50mm, f/1.8

[weeatmice]

Looks promising better than I have managed of the milky way. Did you stop down your 50mm 1.8? It performs well at f2.8 and best at f4 but obviously you have to strike a balance between that and exposure times & ISO.

http://www.astropix.com/HTML/I_ASTROP/LENSES.HTM

Some tips there on apertures for various lenses.

As for focus - some say to use AF on somthing that is effectively at infinity like a distant rooftop or tree. I prefer to use MF & LiveView at 10x magnification though.

[silversldr]

Here is my first try with DSS

http://farm5.static.flickr.com/4078/4804229878_e6d24ffce2_b.jpg (http://www.flickr.com/photos/silversldr/4804229878/)

[A.S.I.G.N. Observatory]

Not bad mate, now just tease out all that hidden data, (Yes, it's in there). Use levels and curves nice and gently, a bit at a time. You will be amazed at what is in there.

Bump up the saturation a little, don't overcook it. Have several goes at it.

Baz.

[A.S.I.G.N. Observatory]

I grabbed your low-res JPG off the forum here and ran it rough and dirty through Photoshop Elements 6, with a bit of levels and saturation twiddling. As you can see, even in this low-data file, there is some hidden pixel values that can be bumped up. You spent the time capturing the data, however faint, why not show it?

Just imagine how this will come out if you take 20 or 30 shots of the same thing, chuck in some darks and flats, you will have a masterpiece on your hands.

Your focus looks ok, but see if you can get it perfect every time. I zoom right in on the brightest star I can find, focus it as best I can, then zoom all the way back out again to take the pic.

You have captured Scorpius and the Sagittarius region, looking at the central bulge of our Milky Way Galaxy. Well done.

Baz

[A.S.I.G.N. Observatory]

Here's the two constellations drawn in. Sagittarius (AKA the teapot) and the Scorpion, (Scorpius). Never, ever call it Scorpio around an astronomer....:lol:

Baz.

[silversldr]

Oh wow. That is awesome. Thanks

[Madweasel]

Your focus looks ok, but see if you can get it perfect every time. I zoom right in on the brightest star I can find, focus it as best I can, then zoom all the way back out again to take the pic.

Be careful - with many modern zooms this does not work. At one time this was the accepted method, when zooms were 'parfocal' meaning focus didn't change as you zoomed. Now everything is AF, under normal circumstances the camera looks after focus, so the lens designers can drop that design constraint. You may well find that what is sharp when zoomed in can go off when you zoom back out. The safest way is if you have Liveview - then you can zoom in the image without zooming the lens. Focus manually that way on a bright star and you're set.

[A.S.I.G.N. Observatory]

Be careful - with many modern zooms this does not work. At one time this was the accepted method, when zooms were 'parfocal' meaning focus didn't change as you zoomed. Now everything is AF, under normal circumstances the camera looks after focus, so the lens designers can drop that design constraint. You may well find that what is sharp when zoomed in can go off when you zoom back out. The safest way is if you have Liveview - then you can zoom in the image without zooming the lens. Focus manually that way on a bright star and you're set.
Live view is an awesome tool, I agree and I now us this as of last weeks arrival of my new 5D MK II. However, a lot of earlier cameras (and I'm only talking three years) don't have the luxury of live view. When you are talking about short focal lengths like this, focused at infinity then backed of slightly, as long as the focal range when zoomed in is not ridiculous, then it should be fine for the task.

Make sure the lens is on manual focus and do it by hand.

[silversldr]

I just recently upgraded to the 7D from the xti and had the luxory of trying live view for the first time that night. I noticed that it can be a little difficult finding the stars in live view if your focus isnt close to be right on. I found that looking through the viewfinder to find the bright star and than switching to lv helps tremendously.

I do have a question from earlier. You used curves and levels to pull more detail out. I thought I got as much out as I could doing the same thing (obviously I didn't). Anythin in particular that you did to get the last bit out?

Also I did take darks and forgot to apply when I processed it in DSS. In your tutorial, you don't go over flats. What are they and how can I take them?

[A.S.I.G.N. Observatory]

I just recently upgraded to the 7D from the xti and had the luxory of trying live view for the first time that night. I noticed that it can be a little difficult finding the stars in live view if your focus isnt close to be right on. I found that looking through the viewfinder to find the bright star and than switching to lv helps tremendously.

I do have a question from earlier. You used curves and levels to pull more detail out. I thought I got as much out as I could doing the same thing (obviously I didn't). Anythin in particular that you did to get the last bit out?

Also I did take darks and forgot to apply when I processed it in DSS. In your tutorial, you don't go over flats. What are they and how can I take them?

I can see I am going to have to write another tutorial on darks and flats... I get this question all the time and it is in my nature to try to help.

Flats are taken at an evenly lit surface, like a white wall, the clear sky just after the sun has gone down, or some white illuminated cloth stretched over your lens.

You need to experiment with the shutter speed, (quite fast), but you should get a white image with darkened corners (vignetting). These frames are loaded into DSS as well and identify the uneven lighting coming down a round lens, onto a square sensor, showing the light "fall off". What they do is compensate by lightening the corners in the opposite graduation to which they are naturally darkened, therefore "flattening" your image. They also recognise "dust bunnies" and dust motes in the image train and remove them from your subs.

[mtbdudex]

Live view is an awesome tool, I agree and I now us this as of last weeks arrival of my new 5D MK II. However, a lot of earlier cameras (and I'm only talking three years) don't have the luxury of live view. When you are talking about short focal lengths like this, focused at infinity then backed of slightly, as long as the focal range when zoomed in is not ridiculous, then it should be fine for the task.

Make sure the lens is on manual focus and do it by hand.


To help live view I've temp upped the ISO to 3200 or 6400, then easier to focus a crisp and sharp star "dot", then turned back to desired ISO for actual shot(s). When in doubt or using the viewfinder, I've found that going back/forth the seemed focus mid-point can help one narrow to true in-focus spot. Just a few OJT focus tricks, learned while mosquitoes biting...

[mtbdudex]

I can see I am going to have to write another tutorial on darks and flats... I get this question all the time and it is in my nature to try to help.

Flats are taken at an evenly lit surface, like a white wall, the clear sky just after the sun has gone down, or some white illuminated cloth stretched over your lens.

You need to experiment with the shutter speed, (quite fast), but you should get a white image with darkened corners (vignetting). These frames are loaded into DSS as well and identify the uneven lighting coming down a round lens, onto a square sensor, showing the light "fall off". What they do is compensate by lightening the corners in the opposite graduation to which they are naturally darkened, therefore "flattening" your image. They also recognise "dust bunnies" and dust motes in the image train and remove them from your subs.

For flat frames I've done the white t-shirt over the lens pointing at bright sky (not direct at sun) and that is very easy. Good thing to do the morning after a long evening/morning of shooting with a 2nd memory card while your primary memory card is downloading....pass the time.

[Jonathan.kichizi]

To help live view I've temp upped the ISO to 3200 or 6400, then easier to focus a crisp and sharp star "dot", then turned back to desired ISO for actual shot(s). When in doubt or using the viewfinder, I've found that going back/forth the seemed focus mid-point can help one narrow to true in-focus spot. Just a few OJT focus tricks, learned while mosquitoes biting...

Have you tried going into your liveview settings and turning off "exposure simulation"? I think that this causes the camera to use max ISO if necessary to get a good liveview picture on the screen. The exposure of image you see on the screen will be unrelated to the exposure of the photo you take, instead it is optimized for view-ability.

I'll have to experiment with it to determine if it will actually bring the ISO of the liveview picture to 6400 when exposure simulation is off.

[MCB]

Thanks for the great tutorial!

I have tried star trails a few times and am hoping to get some good shots for DSS soon. I wish I had known about this a few weeks ago when I could have gotten some great light-pollution free shots while on vacation... oh well.

But here are some questions:

I am shooting with a 40D and am wondering what experience people have had with various ISO settings. Is ISO 1600 too high? Will it be too grainy?

I am shooting on a tripod with no tracking and am wondering about the ideal exposure length for good registration in DSS. If I'm at 24mm will I see too much motion at 30 seconds? How about if I am at 100mm or even 400mm? Do my exposures need to be shorter, like 5-10 seconds?

For my bias frames, can I take a set of those and just use them over and over again for different sets of light images? (understanding that I would need a set for each ISO value)

How about the flat frames? I can use one set of flat frames per lens (focal length)? The DSS manual says to use the same ISO, and it seems like the lens/focal length would be important. But once I have a set for a particular combination (ISO 800 on the 400mm) i can just use that every time in the future, right?

Also with flat frames, the exposure time doesn't need to match, right? I just want a good exposure, not something blown out. Right?

And... what's a flat dark? I understand flat frames and dark frames... but is a "flat dark" really what it sounds like? I shoot a white surface in the dark? The DSS manual says you can skip that, but does it help? Do people use that?

Whew. That's it for now. Thanks again for the tutorial, and thanks in advance for any additional suggestions!

[MCB]

Oh, and one more...

With all this stacking and improving the signal to noise ratio, do we really need to use RAW files? Does that add much to the final image? Are jpgs okay?

Is there a difference from a work flow standpoint?

I haven't tried it yet. But from the manual, i don't understand what the parameters are for in the "RAW Files" dialog box. Do I just leave all those parameters at 1.00?

Thanks again.

[martyn_bannister]

What would be good would be a set of frames to practice on. I have around 100 frames which I shot night before last to try to get Perseids (not very successfully!). Along with the light frames, I also have dark, flat, dark flat and offset/bias shots. They are all shot as JPG. If anyone is interested, I can make them available for download. Aside from the light frames I have 16 frames each of the others. Is this too many?

[MCB]

... Along with the light frames, I also have dark, flat, dark flat and offset/bias shots. They are all shot as JPG. ... from the light frames I have 16 frames each of the others. Is this too many?

From the DSS FAQ it looks like 10-20 of each is good. BUT in the "how to create better images" section he implies that there is really no upper limit, and that you get increasingly less noise if you use 100 or more.

He explains that if you have too few dark images (for example) you will actually be introducing MORE noise into your shot. The same goes for flat and bias images. So... I took about 100 of each. Overkill? Hard drive space is cheap and i can go watch cartoons with the kids while the program chugs away. :) Will it help? Not with my horrible light frames.

[luigis]

JPGs are not a good idea for stacking, first of all JPGs are only 8 bits so you are losing information that can be very valuable for the stacking program, specially in astrophotography. Then the JPG compression artifacts will impact the quality of the final image. Either use RAW files directly or convert your RAWs to 16bit Tiffs using your preferred software.

[naivri]

Hi Barry

First - I love your work and really appreciate the tutorial - saved me weeks of guessing

THought I would post here as per your request for people to post if they followed your tutorial word for word

I did and was diappointed with my results. 99% of that i'm sure was me not being able to focus properly (or more accurately, thinking I was focussed properly). its a learning curve for me - next time i'll have my laptop with me and use it to view pictures right away to get the focus right. Plus I need to find a way to stop my damn lens from steaming up >.<

One thing I did notice though using DSS latest version (3.3.2).

I followed your instructions for the stacking parameters section to the letter, but noticed that what I was seeing was different from your screenshots. I'm guessing that is maybe due to you not mentioning some default parameters which may have changed over the year or so since you made your excellent tutorial

I found that I had to go into the cosmetic tab and check detect and clean hot/cold pixels - selecting 2px and 50% threshold that are showing in your tutorial screen cap in section 10. I also had to click on RGB channels background calibration in the Light tab and select RGB channels background calibration as opposed to per channel.

This gave me a stacking parameters dialog box the smae as the one in your tut as section 10.

This gave me 200x better results.

Like I said, maybe the default parameters have changed over the year or so in new version (or maybe I missed something really simple in your tutorial)

I'm totally new to the program so offering my nublet experience with it

[naivri]

Here is my first attempt

http://farm5.static.flickr.com/4094/4898671466_e2571d5e39_b.jpg

[luigis]

Hi Naivri,

Focus seems to be off. I don't know what camera you are using. If you have live-view use live-view at 10x to manual focus. If you don't have live-view you can try a green laser pointer pointed to the sky and the camera AF. Without a laser pointer you can focus at a very distant object at daytime and then mark the focus position so you can re-use it at night.

[naivri]

Hi Naivri,

Focus seems to be off. I don't know what camera you are using. If you have live-view use live-view at 10x to manual focus. If you don't have live-view you can try a green laser pointer pointed to the sky and the camera AF. Without a laser pointer you can focus at a very distant object at daytime and then mark the focus position so you can re-use it at night.

Thanks for the tips

PS i checked your site, your pictures are awesome

[PhotosbyKev]

Excellent tutorial and also some great advice. My first attempt at astrophotography was the Milky Way, now I'm hooked and the weather is awful lol. I focussed using a manual guess for infinity and then used the x10 magnification of Live view to get a star as sharp as possible.

http://farm5.static.flickr.com/4117/4899602406_092b463560_b.jpg

Taken at Cemlyn Bay on Anglesey in N. Wales. (N is left and E is bottom)
43 images and 8 dark frames on a Canon 5D mkII and Canon f1.4L mkII lens.
15 seconds @ f2 iso 1600
Stars registered in Deep Sky Stacker and post processed in Photoshop CS5.

If anyone can overlay a few star labels etc it would be appreciated because I just can't see any obvious ones.

A larger version is on my website which gives even more detail

[luigis]

Excellent tutorial and also some great advice. My first attempt at astrophotography was the Milky Way, now I'm hooked and the weather is awful lol. I focussed using a manual guess for infinity and then used the x10 magnification of Live view to get a star as sharp as possible.

http://farm5.static.flickr.com/4117/4899602406_092b463560_b.jpg

Taken at Cemlyn Bay on Anglesey in N. Wales. (N is left and E is bottom)
43 images and 8 dark frames on a Canon 5D mkII and Canon f1.4L mkII lens.
15 seconds @ f2 iso 1600
Stars registered in Deep Sky Stacker and post processed in Photoshop CS5.

If anyone can overlay a few star labels etc it would be appreciated because I just can't see any obvious ones.

A larger version is on my website which gives even more detail

First attempt? Wow, you should look at my first attempts when you need a laugh!

I went to your website to check the large version.
I think you processed a little too much, the background seems to be a little clipped, the sky is never pitch black. Can also be a little oversharpened to my taste. Some stars exhibit some shape problems specially at the bottom left.
Focus seems to be really good, saturation and color look very good too.
I think you didn't say the focal length for the shot, that may help me find what you captured if you make me guess I'd say some area of Sagitarius.

[SteveInNZ]

I'll take a stab.
That looks like the North America Nebula to me and a few stars line up pretty well so my guess is Cygnus (The Swan). That would make the lens a 28mm on a full frame.
If I'm right, the red bit labeled 5000 is the North America Nebula. The star close to it is Deneb. The cross shape is the constellation Cygnus and the small parallelogram on the top right is Lyra with the bright star above it, Vega.
I could be wrong as I've only seen that patch of sky once. It only just scrapes above the horizon here.

Steve.

[luigis]

Well done Steve, I was never going to be able to do it, I live in the southern hemisphere too and that is a very unfamiliar part of the sky to me!
Amazing what you did!

[luigis]

Focal should be 24,, and the lens the 24mm mkIIL f1.4

[PhotosbyKev]

First attempt? Wow, you should look at my first attempts when you need a laugh!

I went to your website to check the large version.
I think you processed a little too much, the background seems to be a little clipped, the sky is never pitch black. Can also be a little oversharpened to my taste. Some stars exhibit some shape problems specially at the bottom left.
Focus seems to be really good, saturation and color look very good too.
I think you didn't say the focal length for the shot, that may help me find what you captured if you make me guess I'd say some area of Sagitarius.

Sorry I did state the lens but missed the all important part lol it was with a Canon 24mm f1.4L mkII lens. There was some rotational errors in the corners so I cropped the image to about 80% of the full frame. I haven't applied any sharpening in the CS5 processing but I assume DSS is applying some form of sharpening. The black was set at around 10-15 above pure black which I think is too much as you've commented, it wouldn't be difficult to lift it a bit more.

Thank you for your comments they will help me next time I get out :)

[PhotosbyKev]

I'll take a stab.
That looks like the North America Nebula to me and a few stars line up pretty well so my guess is Cygnus (The Swan). That would make the lens a 28mm on a full frame.
If I'm right, the red bit labeled 5000 is the North America Nebula. The star close to it is Deneb. The cross shape is the constellation Cygnus and the small parallelogram on the top right is Lyra with the bright star above it, Vega.
I could be wrong as I've only seen that patch of sky once. It only just scrapes above the horizon here.

Steve.

Thank you for the effort Steve. I was trying to visualise the image using Starry nights and your overlay has made it easy to locate now.

[Badger49456]

Back on topic...has anyone here now gone out and tried image stacking, based on my tutorial? How did you go? Has anyone got a picture as a result of learning from this tutorial?

Baz.

I just did! I'm very pleased with the results! It was weeatmice's image back on page 3 that made me go out and try it; I was so impressed by his/her results with the 85mm 1.8 that I just had to give it a go.

I set up my really, really crappy tripod on the back deck and pointed my 30D and Tamron 28-75mm 2.8 in the direction of Andromeda at 28mm. Once I found it, I centered it and zoomed in to 75mm, then I manually adjusted the focus as best I could.

This is the result of 22 light frames at 75mm, f2.8, ISO 1600 and 13" (which in hindsight was too long as I had the start of trails) + 23 dark frames.

http://farm5.static.flickr.com/4154/4985673376_de234ce962_z.jpg (http://www.flickr.com/photos/nathmath/4985673376/)
Andromeda Galaxy (http://www.flickr.com/photos/nathmath/4985673376/) by Shaman Tanthew (http://www.flickr.com/people/nathmath/), on Flickr

[naivri]

Had no idea Andromeda can be so prominent at 28mm

Roll on winter and early nights ! Last time I tried this I had to wait till past midnight for 30 sec exposures to be black and not blue

[Madweasel]

Had no idea Andromeda can be so prominent at 28mm

Roll on winter and early nights ! Last time I tried this I had to wait till past midnight for 30 sec exposures to be black and not blue
From my position, 30-second exposures have an orange sky, thanks to the low-pressure sodium street lighting. But you can darken the sky through processing, including using DSS.

If you check the wording of the post, the shot was taken at the 75mm end of the zoom, not 28mm.

[theague]

Back on topic...has anyone here now gone out and tried image stacking, based on my tutorial? How did you go? Has anyone got a picture as a result of learning from this tutorial?

Baz.

Well I was in a fairly dark area last weekend so I thought I'd give DSS a go. I must have missed the milky way or something? lol

http://agueimages.zenfolio.com/img/s8/v11/p736877218-4.jpg

It's 107 images stacked.

Here's the star trail version. I think I need to edit out the plane but am not looking forward to it. =/

http://agueimages.zenfolio.com/img/s9/v14/p806235558-4.jpg

[martyn_bannister]

Well I was in a fairly dark area last weekend so I thought I'd give DSS a go. I must have missed the milky way or something? lol

http://agueimages.zenfolio.com/img/s8/v11/p736877218-4.jpg

It's 107 images stacked.

Here's the star trail version. I think I need to edit out the plane but am not looking forward to it. =/

http://agueimages.zenfolio.com/img/s9/v14/p806235558-4.jpg

NIce one :)

Rather than edit the result, just remove the offending few frames with the plane and recompile the result.

[theague]

NIce one :)

Rather than edit the result, just remove the offending few frames with the plane and recompile the result.

If I do that there will be gaps in the star trails. There are two frames, I'm thinking I might just edit those frames before compiling them in startrails.de - we'll see.

[martyn_bannister]

If I do that there will be gaps in the star trails. There are two frames, I'm thinking I might just edit those frames before compiling them in startrails.de - we'll see.

Good point! Sorry :o

[troypiggo]

If you're into star trails and want to fill in gaps, you might be interested in Star Tracer (http://www.tawbaware.com/startracer.htm). I haven't used it before, have no affiliations with them etc. Just noticed it one day while searching around and thought it looked cool. Not free, but looks pretty cool.

[theague]

If you're into star trails and want to fill in gaps, you might be interested in Star Tracer (http://www.tawbaware.com/startracer.htm). I haven't used it before, have no affiliations with them etc. Just noticed it one day while searching around and thought it looked cool. Not free, but looks pretty cool.

Looks like a cool program. I'll have to download the shareware version and see how well it works :)

Thanks for the tip!

[PhotosbyKev]

NIce one :)

Rather than edit the result, just remove the offending few frames with the plane and recompile the result.

Rather than remove the frames, a better result is to edit the individual frames to remove the segments of the aircraft trail and then recompile the image

[BASmith]

I tried to get this right last Autumn...with no success.
However this could still be better but at least it is better than my first bumbling attempts.
Now I KNOW it can be done with a 18-55 KIT Lens.

http://i103.photobucket.com/albums/m139/gerbalhunter/Stars%20and%20Nebulas/MilkyWay.jpg

[K.K.]

My first image with Milkyway, panorama from 3 frames in PTGui, processed in CS4.
http://miedzinjsh.files.wordpress.com/2010/10/img_0384p_1x.jpg
Canon 5D mkII + 24-70 F/2.8L @24mm, iso3200, f2.8, 30s

How do you think, is it possible to use DSS with pictures where is foreground visible in the frame?

[luigis]

^^^ K.K. Very nice image.

I wrote a small article on my blog about stacking landscapes with DSS : http://theamazinglight.wordpress.com/2010/08/21/stacking-night-landscapes-with-dss/
You just have to stack twice, once for the stars and once for the ground (without alignment) then merge both results as a single frame. The process is easy in shots like yours where the foreground doesn't impact in the sky a lot.
I hope it helps!

[NukeGM]

Very nice shot!

Much better than my 1st attempt :)

[VisualUniverse]

My first image with Milkyway, panorama from 3 frames in PTGui, processed in CS4.

Canon 5D mkII + 24-70 F/2.8L @24mm, iso3200, f2.8, 30s


Nice capture!

[A.S.I.G.N. Observatory]

Good work people, keep it up!

Baz.

[04yellowf150]

Talk about being inspired with these pics. I havent used DSS yet but ive done enough reading to make my head hurt. still dont fully understand the whole flats and lights, the darks i do lol.

I have a t2i with a kit lens, horrible tripod and and no shutter release not to mention im new to photography.

none the less this forum is awesome. Thanks for posting all this for a noobie like myself haha

[A.S.I.G.N. Observatory]

I have a t2i with a kit lens, horrible tripod and and no shutter release not to mention im new to photography.


Stick your camera on your horrible tripod and use an elastic strap from the tripod head to a tent-peg banged into the ground. Use your wide angle lens (say 18mm or so) on the brightest part of the milky way you can see, set your aperture for wide open (say f3.5 or so), set your shutter to bulb for 30 seconds and use your delay timer to trip the shutter. Set your ISO at about 800.

You will have the makings of a good wide-field of the milky way.

As good a place as any to start!

Baz.

[J-RoN]

These pictures and the tutorials have really helped me understand all of this and now I can't wait to go out and start shooting. Soon as finals are over I'm out of the city and back to my rural county where the stars fill the skies :)

[A.S.I.G.N. Observatory]

These pictures and the tutorials have really helped me understand all of this and now I can't wait to go out and start shooting. Soon as finals are over I'm out of the city and back to my rural county where the stars fill the skies :)

And he's off and racing!!:cool:

Baz.

[swag72]

Hi Baz, I am currently using your tutorial and so far it seems excellent - Running through DSS at the moment. Just like to say that things have obviously been updated by DSS as at your stage 9 (recommended settings) the parameters have changed, the selection you state is no longer available.

So, not sure what selection I should be making here. Seems simple tutorial so far - Thanks very much.

[luigis]

Hi Baz, I am currently using your tutorial and so far it seems excellent - Running through DSS at the moment. Just like to say that things have obviously been updated by DSS as at your stage 9 (recommended settings) the parameters have changed, the selection you state is no longer available.

So, not sure what selection I should be making here. Seems simple tutorial so far - Thanks very much.

Median is still one of the stacking methods.

If you only have a few images I recommend using "Average" or "Median" if you need to remove trails of airplanes or similar.

If you have a good number of images then use Weighted Average or Kappa-Sigma-Clipping.

[torontophotos]

Baz,
Been subscribed to this thread for sometime, and finally got myself a remote shutter release timer to do some astro shots! I have a few questions after reading your tutorial:

1. Do you have the Milky Way jpg's available for download anywhere so I can attempt to stack them in DSS? I'd like to start off with a sample that works before so I know what I'm doing before I do this on my own.

2. Of my equipment list below, what do you think will give me the best chance of getting a good capture?

Camera: Canon 50d
Lens Collection: 24-105 f/4, 50 f/1.8, Tamron 18-270 f/3.5-6.3
Tripod: Manfrotto with ballhead

3. Will 30 sec exposures be too long without tracking equipment? Or do I just play with this until I get something that looks ok on my LCD?

4. What's the max ISO I should go to? I've done 1600 ISO portraits that look ok, never gone higher though, I think the camera goes up to 12,800 but I'd imagine that would be very grainy, any suggestions?

Thanks for the writeup and this thread, I'm totally inspired here and would be ecstatic if I could capture either Andromeda or the Orion Nebula. I live in Toronto, Canada if that matters :)

Cheers!

[Techuser]

First stack, shot this weekend
used the 450D, 18-55 with four 30 seconds

Cant wait to try with the milky way...

http://farm6.static.flickr.com/5263/5701574268_7cabcf8bdd_z.jpg

[luigis]

First stack, shot this weekend
used the 450D, 18-55 with four 30 seconds

Cant wait to try with the milky way...

http://farm6.static.flickr.com/5263/5701574268_7cabcf8bdd_z.jpg

That IS part of the Milky Way. You have the Eta-Carina Nebula, Centaurus, Crux and the Coalsack nebula there.
The brightest part of the Mway is at Scorpius/Sagitarius and it's just getting higher and higher in the sky at nigh from your location.

[AJX]

I'm really Astonished with these pictures , i've never imagined that this would be done with a DSLR , i'm rushing the time and waiting for the summer as i'll be in Russia ( in my summerhouse ) 25km out side Saint-Petersburg where the light pollution is 0% , and my 1000D will do the thing i guess ? :)

[Madweasel]

Why wait until Summer? I'm sure there must be plenty of dark locations in Jordan, and the Winter constellations are great.

[AJX]

Why wait until Summer? I'm sure there must be plenty of dark locations in Jordan, and the Winter constellations are great.

I know there is , but the clouds are the problem now :(

[A.S.I.G.N. Observatory]

Baz,
Been subscribed to this thread for sometime, and finally got myself a remote shutter release timer to do some astro shots! I have a few questions after reading your tutorial:

1. Do you have the Milky Way jpg's available for download anywhere so I can attempt to stack them in DSS? I'd like to start off with a sample that works before so I know what I'm doing before I do this on my own.

2. Of my equipment list below, what do you think will give me the best chance of getting a good capture?

Camera: Canon 50d
Lens Collection: 24-105 f/4, 50 f/1.8, Tamron 18-270 f/3.5-6.3
Tripod: Manfrotto with ballhead

3. Will 30 sec exposures be too long without tracking equipment? Or do I just play with this until I get something that looks ok on my LCD?

4. What's the max ISO I should go to? I've done 1600 ISO portraits that look ok, never gone higher though, I think the camera goes up to 12,800 but I'd imagine that would be very grainy, any suggestions?

Thanks for the writeup and this thread, I'm totally inspired here and would be ecstatic if I could capture either Andromeda or the Orion Nebula. I live in Toronto, Canada if that matters :)

Cheers!

Hi mate. Sorry it took me so long to reply. I'll answer as best I can.

1. Short answer...no. Long answer.... no. :lol:
2. 24-105 on 24mm (I'd get a shorter FL lens, like 16mm.) Camera and Tripod are fine.
3. I find my stars are getting a little eggy at 18mm at 30 seconds. At 16mm it's nowhere near as bad. The longer the focal length, the shorter your exposures will be before they show star movement.
4. I wouldn't go beyond 1600. I normally shoot on 800 with my 5DII.
For decent and detailed shots of the Orion nebula and Andromeda, you will need longer focal lengths and a tracking mount. No getting around that.

My pleasure mate! Good luck!

Baz.

[Jonathan.kichizi]

Hi mate. Sorry it took me so long to reply. I'll answer as best I can.

Baz.

Haha, that was almost a year.

Baz, did you finish your new observatory before the end of the year?

[Korak]

Just a really noob question:
Last night finally clouds breaking little bit, so me and my son went to try out first star pics.
Lots of lightpollution coming, and didnt get stars razorsharp. OK thats not problem, more practising.
:)
But question about when trying to do DSS. My RAW resolutions come as they suppose to be 5184 x 3456. Showing only 1336 x 3516.
http://imageshack.us/f/9/rawresolution.jpg/
Thou I can see original resolution on Adobe Lightroom. And when I changed photos to jpeg, and then just trying DSS with jpegs, and you can see photos as 5184 x 3456.
Any ideas what is wrong?

I was using Canon 550D, with ES-F 15-85 IS USM at 3.5F
Took 30 photos @ 20sec ... 10 darks and 10 Bias .. with ISO 1600 (next time trying 800)

And all I can do now, is because something with that DSS resolution change that just playing with 10 stacked jpegs
http://img7.imageshack.us/img7/4412/testiastrolle1of1.jpg (http://imageshack.us/photo/my-images/7/testiastrolle1of1.jpg/)


And here is one raw image 15mm wide same specs as earlier mentioned (worked with lightroom)
http://imageshack.us/f/26/thtitaivas1of1.jpg/

EDIT: Ok, I find the solution. I was using only 3.3.2 ... so 3.3.3 beta45 fix the things for resolution. Now I only wish I can be better photographer LOL :D

[Slave7081]

Awesome tips i'm reading here.

I can't wait to get back to an area where I can take some night shots again....disadvantage to living in the big city I guess :P