Star Trail Stacking

Discussion in 'Digital Photography' started by Dhelsdon, May 26, 2012.

  1. Dhelsdon macrumors 65816

    Dhelsdon

    Joined:
    Feb 5, 2010
    Location:
    Canadian Eh!
    #1
    What's everyone using for image stacking (RAW or JPG)

    I tried shooting star trails for the first time tonight with my canon 450D at ISO 100 f5.6 with 30 sec exposures, 1 min between each shot. I can see the stars for each individual shot looking at the images, but when I try to stack them using Keith's Image Stacker it just shows up as a black image.. not sure what I am doing wrong.

    Based on the settings I provided can anyone give any recommendations?

    I am starting to think that the 1 min between each shot was too long, looking at the images I captured, the gap between a single stars movement is quite significant.
     
  2. snberk103 macrumors 603

    Joined:
    Oct 22, 2007
    Location:
    An Island in the Salish Sea
    #2
    I have no experience with star trails, stacking or otherwise... but I do have a fair bit of experience with photography in general... so take this advice accordingly.

    Also, I am assuming a basic level of photographic knowledge... so if I've assumed wrong and ended up talking down to you, please forgive me - it is unintentional. There isn't a lot of information in your post so it's hard to gauge the level of knowledge.

    I would think the gap between exposures is way too long. Ideally, there shouldn't be a gap. Think of it this way. The stars are moving at a predictable rate; at 0.25º per minute. That is .... a quarter of one degree per minute. So... you expose for 1/8 of one degree of movement, and then let them move for a quarter of a degree between exposures.

    You didn't state what focal length lense you used, and that is critical too. One piece of advice I read (here in the DP forum!) was that a rule of thumb was 600/lense-focal-length. This is gives you the maximum exposure time to before trails start to become noticeable. So, less time for pinpoint stars and more time for trails. I haven't tried this, but it comes from someone who seemed to know what they were talking about.

    Somewhere on the 'net you will find the field of view (in degrees) for the lense you are using. If, for example, it's 25º you can easily calculate how far across the image the trails will move for whatever exposure time you use.

    If I were stacking I'd use RAW and Photoshop. There is a layer blending mode that should preserve the blackness of the sky.

    Just thinking out loud here....it should be easy to import the set into Lightroom, and use the graduated filter to bring out the trees. You need to do just one and then synch the rest, and adjust as necessary. Then move set to Photoshop to stack and blend. Hmm.... I may have to try it..... I just got an AC power adapter for the camera and I can power the databack from a laptop. Hmmmmmmm........ :)

    Luck.

    ps Where in Canada, eh? I'm on the far wet coast....
     
  3. acearchie macrumors 68040

    acearchie

    Joined:
    Jan 15, 2006
    #3
    I made this last year from a failed time-lapse.

    [​IMG]
    France Star Trail by acearchie, on Flickr

    From what I can understand you much have had a really bright night to achieve an exposure as I remember having 30 secs exposure wide open (f2.8) and about ISO 800-1600!

    As mentioned above the time between shots maybe too much.

    Have you tried any other software? This is a link to the one I used which may work better for you.
     
  4. Prodo123 macrumors 68020

    Prodo123

    Joined:
    Nov 18, 2010
    #4
    Love the shot, doesn't look like a failure to me!
    But personally I think 30 seconds are too long for a time lapse, unless you wanted the trails in the video.
     
  5. acearchie macrumors 68040

    acearchie

    Joined:
    Jan 15, 2006
    #5
    It was only a failure as a video as the house was overexposed for a lot of the night and I couldn't be bothered to correct it for the video however, for the still image it was as simple as taking it into photoshop and taking down the exposure a tad.

    I try and avoid the trails as well but on my Tokina 11-16mm I found I could just get away with 30secs at the wide end and this was better than speeding up the shutter and increasing the noise with the ISO as I am only shooting on a 600d.

    Thanks for the feedback!
     
  6. Dhelsdon thread starter macrumors 65816

    Dhelsdon

    Joined:
    Feb 5, 2010
    Location:
    Canadian Eh!
    #6
    Forgive me, I posted this at 5am out of frustration with my failed attempt. I was using a kit lens (18-55) at approx 55mm* (I can't remember exactly).. Not going to lie, I am pretty new to photography, according to Lightroom my focal length was just 28mm.

    Basing of what you said earlier 600/2.8mm = 214.28

    Not entirely sure where that leaves me, I am going to assume that is milliseconds? Like I said I am new this :)

    I used the north star as my center point to capture the movement around it, except that I think I was wrong about what I actually thought was the north star.. oops :p

    Hahah the wet coast eh, I am in Edmonton.. actually about 2 hrs north in a small town. I lived on Vancouver Island about 4 years ago and I really miss it!

    I'll continue to play around with the set in LR and PS and see what I can come up with.
     
  7. acearchie macrumors 68040

    acearchie

    Joined:
    Jan 15, 2006
    #7
    I have read the calculation as 1000/Focal Length but that may take into account using a FF FOV rather than a crop FOV.

    For snberk103's calculation the result would be 600/28=21.4 secs or (13.4 if you take into account the FF FOV)

    Using 1000 you get 35.7secs (or 22 secs)

    Did you try the program I mentioned above?
     
  8. Dhelsdon thread starter macrumors 65816

    Dhelsdon

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    #8
    Yes, I just finished actually!

    It worked great, as far as functionality.. my first attempt still sucked. I think I was too zoomed on one point instead of getting a broader range.

    [​IMG]
    stackedImage.jpg by dhelsdon, on Flickr
     
  9. Tomorrow macrumors 604

    Tomorrow

    Joined:
    Mar 2, 2008
    Location:
    Always a day away
    #9
    ^^ Not what I envision as "star trails," but if you're happy with it, that's what matters. :cool:
     
  10. mackmgg macrumors 65816

    mackmgg

    Joined:
    Nov 2, 2007
    #10
    What was the interval between shots? It seems too long to me, which is why they're dots not a continuous streak. With 30" exposures, you should be taking a photo every 30". There shouldn't be a gap. When I do star trail shots, I usually put the camera in continuous shot mode, and just lock the shutter.
     
  11. Dhelsdon thread starter macrumors 65816

    Dhelsdon

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    Canadian Eh!
    #11
    It was a complete failure :)

    I know where I went wrong now, and I am excited to try again.

    ----------

    It was 1 minute, I was unsure at the time and I didn't realize how fast the stars actually moved. Next time I'll be sure to shoot continuously next time and actually find the north star :roll eyes:

    [​IMG]

    This is a reference that I didn't think I needed, I'm my case I was using a star off the "handle" of the big dipper whereas I should've been looking at the opposite end.
     
  12. acearchie macrumors 68040

    acearchie

    Joined:
    Jan 15, 2006
    #12
    You might also want to increase the ISO and expose for longer if you want to get more of the stars visible.

    As you can probably tell from mine I like having something in frame as well as the moving star trails.
     
  13. Dhelsdon thread starter macrumors 65816

    Dhelsdon

    Joined:
    Feb 5, 2010
    Location:
    Canadian Eh!
    #13
    I would as well, but in my current location there's not much options for me. I think that will drive out to my work and try out there sometime, I work at the local airport so there's so much potential (and minimal light pollution, since it's a small town there's no air traffic after sunset.)

    Do you think an ISO of 400 would be too much?
     
  14. snberk103 macrumors 603

    Joined:
    Oct 22, 2007
    Location:
    An Island in the Salish Sea
    #14
    I'm not sure increasing the ISO is good idea... it introduced noise. Better to open the aperture a bit, I would think. Longer is better, of course.

    The beauty of digital is that you can try something and get almost immediate feedback. Even if you have to drag a laptop out with you to see an image on the screen. A shot of several minutes will tell you if you are getting trails properly exposed, and how bad the noise is at an ISO ... though keep in mind that noise will increase with longer exposures. Once you have figured out the ISO and f/stop it's just a matter of leaving the shutter open for longer than the tests.

    Luck. Lots of good advice in this thread....
     
  15. Fezwick macrumors 6502

    Joined:
    Oct 5, 2002
    Location:
    Rhode Island
    #15
    ISO 400 would be fine. I usually shoot mine at f/2, 30 seconds, ISO 200. Use the widest aperture on your lens. Use your widest lens you can so you can capture a lot of stars and potentially something stationary in the frame. A wired shutter release that you can lock is pretty handy for shooting these, too. Here's mine. I wish I got the pole star. My widest lens is only 35mm so it's difficult for me to have a stationary object and the pole star in the frame.

    [​IMG]
     
  16. Laird Knox, May 26, 2012
    Last edited: May 27, 2012

    Laird Knox macrumors 68000

    Joined:
    Jun 18, 2010
    #16
    You are on the right track. I like to take night shots and have made several outings to try and catch some meteors. A couple of months ago I went to Death Valley with some friends during the Lyrids. I set the camera up and told it to take pictures for six hours.

    I was looking for pinpoint stars with a meteor or two so I kept within the rule of 600. I didn't have any luck on the meteors so the next morning I played around with making a time-lapse. It was OK but I was only using iMovie and it wouldn't let me set the frames to anything faster than .1 sec and it was rather slow.

    When I got home I looked up stacking software and found StarStaX as mentioned above. I was shooting and RAW + JPG and StarStaX processed the 720 JPGs in about five minutes right off of the camera output and resulted in this image.

    [​IMG]

    This was taken with a Nikon D7000 and a Tokina 11-16mm lens. The zoom was set to 11mm so the rule of 600 would dictate a maximum exposure of 600 / (11 * 1.5) = 36 seconds. Using the built in intervalometer I setup the camera to take one 25 second exposure ever 30 seconds. I chose 30 seconds so that time calculations would be easier. The 25 second exposure was because the camera would skip shots when I set it to 30/30.

    I was shooting at ISO 800, f2.8 and the corners wound up rather soft. What is amazing is that it was so calm that night that the trees didn't get completely blurred. You can see a few airplanes in the shot and I later removed them from the individual frames. Even with the settings I used you can see gaps in some of the trails. The trees are lit by the campfire in about 100 of the images.

    Some notes:

    The rule of 600 gives you a good baseline for shooting a pinpoint star. The closer to that limit the more your stars will start to elongate.

    Stacking photos helps to remove noise from the final image.

    If going for star trails see how long you can push your camera before the image starts to get objectionable. Then minimize the time between shots. For example if you can shoot a good quality image at three minutes and then pause a second between shots for the camera to process it you will get a much more solid trail.

    Use your ISO and aperture to control how many stars you get in the final image. I think my above photo might have too many trails to the point that it gets distracting. Had I reduced my ISO I would have lost the fainter stars. This would also have changed the play of the campfire on the trees. I don't know if this would have been good or bad - just something I would have had to try. I could have also reduced my aperture to get a sharper image in the corners.

    Experiment and have fun!

    Here is what an individual frame from the above picture looks like:

    [​IMG]

    At the same time I was using a D60 to take a 30 minute exposure:

    [​IMG]

    Notice the sensor noise in the corners and the change in the color of the sky. This is what I meant when I said to push the exposure time to just before the point the image becomes unacceptable.

    This also points to another issue with star trails - the D7000 was tied up for six hours. Having some older bodies (a D60 and two D70s) lets me keep occupied while the camera doing its thing. Eventually I just went to bed and let the camera click away. ;)
     
  17. acearchie macrumors 68040

    acearchie

    Joined:
    Jan 15, 2006
    #17
    Nice shots, I am curious as to the courage you have to just leave your camera. My shot above was taken in France in the garden and whilst I am not in the slightest bit worried about it being stolen what about the elements or wildlife?

    I don't think your camera is weather sealed so did you create some sort of cover for it? I hid mine under a table covered with tarpaulin but still found a bit of morning dew on the lens.
     
  18. Laird Knox macrumors 68000

    Joined:
    Jun 18, 2010
    #18
    I had some worries but not too many. The camera has a little bit of weather sealing but nothing like the pro bodies. If the weather had turned bad I was only ten feet away in a tent. I knew the forecast was good for the next few days. Also we were in Death Valley (well above it actually) so morning dew wasn't a big concern. Finally, I had just gotten a "real" tripod the day before the trip. Any critters big enough to be a problem would have been big enough to be a problem in the tent.

    At least there aren't grizzlies in the area. ;)
     
  19. LumbermanSVO macrumors 65816

    Joined:
    Mar 15, 2007
    Location:
    Denton, TX
    #19
    My local shop sells used XT and XTi bodies for around $200 and I've been thinking that this may be a good source of bodies to be used JUST for time lapse use that I can leave out in the weather and not worry if I kill them. You may want to look into what used equipment your local shop is selling if you want a second camera that can be abused.
     
  20. Dhelsdon thread starter macrumors 65816

    Dhelsdon

    Joined:
    Feb 5, 2010
    Location:
    Canadian Eh!
    #20
    What's your Flickr profile?

    Thanks for the helpful info, I am looking forward to a second attempt next weekend! I'll be sure to try something a little different and with a better FOV..
     
  21. Laird Knox macrumors 68000

    Joined:
    Jun 18, 2010
    #21
    I don't really use Flickr. I'll throw something up there if I want to link it quickly. In any case I'm on as "lairdknox" go figure. ;)

    I was building a web site but that has been on hold for a bit. The original concept was in Flex and can be found at

    photography.jeffknox.com

    Not a lot of work to be seen there atm. I had started redoing it in HTML5 and CSS3 but again it is stalled out at the moment. It will be a liquid design but right now it is fixed around an iPad in landscape orientation. Swiping on the thumbnails and information areas is working but still needs a lot of love.

    HTML Version

    Most of the work has gone into the back end. The pictures are stored in a DB and sized/watermarked on demand.

    Some day I might have something I can show people. ;)

    In any case, looking forward to your new pictures. Keep shooting and experimenting and you will get some good images. :)
     

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