new photo blog

i started this blog in 2006, and it's shifted along with my interests through the years. it's been witness to a lot of learning for me...

still, i feel that i need a home for my photography -- so from now on, i'll be posting my pictures on the journal on my reworked website. if you like my photos, you might decide to follow me there!

my first post is here -- check it out!

as for this blog, i'm not sure what will happen. i don't think i'm willing to let it go, and certainly i'll keep it as an archive, but i need some time to figure it out.

for those of you that pop in from time to time, thanks for the visits and encouragement.


Saturday, July 09, 2011

happy star trails

starship
click it!
i had many requests to explain the technical side of my starship picture, and i decided that, instead of responding individually, i'd write up a DIY. now, i'm no photo expert, and this is just how i did it.  if you have a better idea or information you'd like to contribute, or if you think i've made a mistake somewhere, please let me know.  i'm not here to teach -- i'm here to learn!

this method does not take one huge long exposure -- it uses a bunch of 30-second exposures which are subsequently stacked to form a final composite image.

this post assumes you know how to change camera settings (or have your manual to read up on how).  it also assumes you know basic photoshop skills and perhaps something about layers and layer masks.

so, on with the show...


gear


conditions
  • a very, very dark sky, preferably on a moonless night.
  • something interesting in the environment -- a building, a landmark -- to frame the sky.
  • creature comforts, a blanket, flashlight, ipod, snacks, drinks, company (i had ever-patient and supportive mr.G), bug spray or warm clothing, depending on the season.


before the shoot
  • get there before dark and find a good location.
  • get comfortable.
  • set up your gear -- mount your camera on your tripod, hook up your cable release, compose and focus your shot.  
  • when composing, find a way to make the sky look interesting. imagine what your trails will look like. if you're facing north, you'll most probably get a shot of the north star and cocentric circles. southern skies have broad arcs.
  • focus manually just a breath before infinity. try to find a distant point of light or use the horizon, and focus on that. hint: i find it helpful to focus with live view at a magnification of 10X.
  • without worrying about camera settings (you can set to auto) take a few test shots to decide on the best composition.


shooting settings

maximize light and minimize time between shots..
  • set your camera to JPG -- avoid RAW. normally, i shoot in RAW but i don't want the camera to spend a lot of time saving a large file between shots.
  • turn off  your in-camera noise correction.
  • use as fast a memory card as you have.
  • turn off image preview. you won't need to be chimping between shots anyway.
  • your camera should be on manual. 
  •  you need a large aperture to get as much starlight in your image as possible -- i opened at my widest value of f/3.5.
  • dial up your ISO to increase sensitivity, but not too much. this depends on your camera. to avoid noise, i set my camera to 400 -- beyond that, it's way too noisy for my taste.
  • set your shutter speed to 30 seconds.
  • white balance set to daylight (this, courtesy of anthony ayiomamitis' comment).
  • set your drive mode to continuous shooting.
  • if your camera strap has an eyepiece cover, place it on your viewfinder.
  • if your lens has image stabilization, turn it off.
wait... until... it gets dark...


shooting

  • as soon as you think it's dark enough, press and lock your cable release. your camera will start continuously shooting 30-second exposures. for how long? as long as you have patience for, as long as your battery lasts, as long as you have room in your memory card.
  • stay away from your tripod. i moved it slightly midway, causing a shift in the arcs.
  • relax and enjoy your surroundings. when you've had enough (i lasted 1hr-50mins) unlock your cable release.

extra shots
  • before or after the shoot, take an extra-long exposure (on bulb) of your composition to use as an extra layer for the surroundings in photoshop.
  • if there's no hope of getting any detail from your surroundings that way, you have two options: either do a long exposure shot with your flashlight to light it up a bit or decide that any objects will just have to be dark silhouettes.  in my case, the top part of the ship was lit slightly from some buildings over a hill behind me. i was lucky.
  • pack everything up, check that you're not leaving something behind with the flashlight.


image stacking and post processing
  • copy all your shots onto your computer. put the full sequence of shots into one folder, except for the extra-long exposures for your environment.
  • download this star trails photoshop action.
  • start photoshop and load the star trails file onto your actions palette. i usually just drag-n-drop the ATN file onto photoshop which automatically loads it.
  • create a new, black image with the same pixel dimensions as your JPGs.
  • go to file > automate > batch.  select the source directory, none for output directory and hit OK. wait until the action processes all the images.  when it's finished, you'll have a flat image with your star trails!
  • layer on your extra-long exposure and use a layer mask to hide the sky so that the star trails will show up from the layer below.  flatten the image.
  • go ahead with any other post-processing you might like, to taste.
and you're done... wooohoooo!

if you do experiment with this, i'd love to see it... add a link below on the comments.

happy startrails to you!

©2011 helen sotiriadis

13 comments:

  1. White balance should also be set to DAYLIGHT. Yes, daylight.

    A. Ayiomamitis.

    ReplyDelete
  2. White balance should be set DAYLIGHT. Yes, that is correct: daylight.

    A. Ayiomamitis.

    ReplyDelete
  3. thanks, anthony -- i just added that to the post, with credit to you.  

    ReplyDelete
  4. susibocks9/7/11 06:54

    here's my feedback - i have absolutely no idea what you are talking about, but i think it is most excellent that you want to share your skills. you're a class act! :

    ReplyDelete
  5. Great DIY, thanks for the link for the photoshop action too, I'll give it a shot. I've always done the stacking part my hand, setting the blend mode to screen or lighten.  I've shot many star trails over the years. This post sums up the main gist of how to make star trails fun, in a quick an easy to read layout. The viewfinder trick is important. I just throw my lens cloth over it. Save your chimping for after PS has done its magic

    No so much as feedback, though I know you said you like it so much, but here's a few more tips: 

    Once you've shot your fill of 30 sec exposures, shot one more 30 sec exposure with the lens cap on (I use my hat most of the time) to produce a "black frame" of noise for the stack, this helps in reduction of the random noise that builds up in all the other frames.

    Once you've got your tripod set-up and camera locked down, suspend something heavy from the bottom post to aid in stability even more (yeah, love my Manfrotto too). Most of the time I hang my camera bag, but if I know it's going to be a long night and might need something out of the bag, I'll bring a grocery bag or something similar and fill it with rocks on-site, then hang that from the clip on the bottom of the tripod post. 

    Mirror slap can be an issue on long exposures too, causing some slight vibrations/jitters to show up in your images. I try to lock mine up for anything over 1/30 sec. So, there are two different ways I've tried to solve it, each had varying degrees of success, then combined them for even better results. First one's easy, bring a 5 lb. bag of brown sugar, a large bean bag or, for me, a bag of small decorative rocks, like what I use for my bonsai or others use for aquariums. Once your camera is all locked down, lay the bag across the top of the body and lens to help squelch vibrations set-up from mirror slap. 2nd, and this takes more effort on your part: Use the Mirror Lock-up feature. Now, hit your remote cable release once, give a count of 1, then hit it again and lock the button. The first hit will lock-up the mirror, while the 2nd one opens the shutter after the vibration slap has settled. After 30 sec. you'll hear the shutter close, then quickly repeat the 2-step sequence again. 

    I know, it's more work than just letting it 'rapid fire' 30 sec exposures for an hour. Oh well. Suck it up. An important tip though - Don't take more than 1.5 - 2 sec to trigger again, otherwise you'll have gaps in your star trails - as our little blue marble, with you, your locked down camera, and tripod on it, is spinning pretty fast. OK, I'll admit, I skimp on this one sometimes when I'm feeling lazy. I find it's easiest to just keep the remote in my hand while I'm reading (or ?) in between triggers, ready to squeeze off another shot.

    One more odd observation, that I've done just for fun. I'll stand in one spot, shot one, 30 min stack of images facing West, then another 30 min stack facing East (too much light pollution North on last trip), just to see the different direction/shape of the star trails. Your milage may vary.

    Geez, Sorry I got so long winded, this is almost another (guest) post. I've been known to ramble sometimes. That's my extra 2 pennies worth. And to repeat what Susi (and I'm sure Mr. G too) says, "You're a Class Act!"

    Samples experiments: 
    http://www.flickr.com/photos/masterofmadness/5074278274/in/set-72157625014273238
    http://www.flickr.com/photos/masterofmadness/3370447763/in/set-72157625014273238/

    Tony; Still reigning "Master of Madness"

    ReplyDelete
  6. Great behind the scenes info, Thks for posting and the 'more tips' in comments by 'Tommy', TY too!

    ReplyDelete
  7. great shot superb tips thanks

    ReplyDelete
  8. Μπράβο.Πραγματικά καλές οδηγίες.

    Τάνια

    ReplyDelete
  9. My only comments would be to consider a self timer wired remote trigger like a Canon Timer Remote Controller TC-80N3 (tho I don't think it'll work with your 40D since it has a different connector) that will take some of the tedium out of getting the repetitive shots; no need to avoid raw as pretty much all 40D and later Canons (and similar Nikons too) can buffer 10-30 raw files before hitting a limit, so it will be no problem to save the 1 raw pic in the 30 seconds that the next raw image is being captuered; finally - just that I agree w/ the value of setting the camera to use mirror lockup if possible... tho I've not tried it w/ the wired auto timed remote... (I'll have to give that a whirl later)

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  10. will, you're right -- you should find a way to not have to trigger each shot separately.

    my Canon Remote Switch RS-80N3 locks into place, so the camera repeatedly took 30-second shots, allowing me to relax and enjoy the view.

    ReplyDelete
  11. Good point on the locking of the remote trigger... I've done so many time lapse things during the daylight hours I've just fallen into the "dependence" (of sorts) on the timer capability of the timer remote. Keep on sharin' the wealth!

    ReplyDelete
  12. Gil D. Faingezicht24/1/12 06:55

    Hi!
    here is a link to my shot! comments are welcome

    https://plus.google.com/110170478425532185128/posts/UVPjZqkXoJL

    ReplyDelete