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Thread: How to take star photos/making a time lapse with a Nikon D40X

  1. #1
    Member Camphor53's Avatar
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    How to take star photos/making a time lapse with a Nikon D40X

    I'm not a photographer, but I've always thought astrophotography was cool. High quality photos showing an awesome amount of stars are great. Time lapses too. I've borrowed a Nikon D40X and have decided to try it out for myself. The lens is 18-55mm and the possible ISO settings are 100, 200, 400, 800, 1600 and H1/3200. The exposure time can go from 1/4000th of a second to 30 seconds, then goes to BLUR.

    Basically I just set the camera up on a tripod and started taking photos with the remote. I didn't really know what settings I was messing with, except it was on "Auto (no flash)" which got rid of the "subject is too dark" message, and the photos seemed best when the ISO was on 800. When I hit the remote it took 25 seconds to shoot. Does this mean that it took 25 seconds to collect enough light? After it shot I waited ten seconds and pressed it again. I did this for 43 photos.

    Here's the first photo I took of the 43. It's converted to JPG from NEF (Nikon's RAW format). The resolution is 3900 x 2613. (Crux is visible over to the right)
    http://img695.imageshack.us/img695/8385/dsc00871ox.jpg

    Are the stars so blurry in this photo because it was very windy? I know that we see stars as "twinkling" because the powerful winds in the atmosphere shakes their light around.

    Then I put each photo in a small timelapse video. There's 100 milliseconds between each frame.
    http://www.youtube.com/watch?v=e0GiReEnfHk

    The location I took these in is a city so there's lots of light pollution, but I'm going up to a very dark rural place soon and that's why I really want to learn how to do this properly.

    Using the camera today I now know how to set it to Manual, and set the aperture and exposure length. I want to take more photos tonight though, so are there any specific camera settings I should be using? Does anyone have any tips for a beginner? I get that less light means more exposure but there's still more to it.

    By the way, with time lapses, when people get shooting stars in their time lapses, how quickly are they taking their photos?
    Like in this one: http://www.youtube.com/watch?v=0kPw3rNSQrE

    Plus what program is generally used to put all the photos together? I use AVS Video Editor but each photo is set to display for 5 seconds by default. I had to go through and change the duration to 100 milliseconds on each 43 photos. It took a long time.

    Thanks.

  2. #2
    A royal pain in the bum! arthurking83's Avatar
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    Quote Originally Posted by Camphor53 View Post
    .....The exposure time can go from 1/4000th of a second to 30 seconds, then goes to BLUR.

    .....
    BLUR should read BULB!

    as for specific settings, there is no one set of settings that works for all conditions. Experience in doing this is the best guide.

    When you shot and it took 25 seconds to make an exposure, this means that the camera's meter must have decided that 25sec was enough exposure time to capture an exposure as set in the camera.
    This actually means a lot of things tho!
    If the camera to exposure the scene with 0Ev compensation, then it has tried to expose the scene as best as it can for a neutral brightness. Not too dark but not too bright either.
    The metering mode used is also a factor here too. If you maintained the default Matrix Metering mode, then the camera will try to expose the entire scene, taking in all variables such as black sky and bright lights without under or over exposing any of the variable brightnesses in the scene.. but remember!! only as best as it can!(there are dynamic range limitations to be aware of).

    If you still have access to the camera, one thing you could try is to take a test exposure using Aperture Priority mode.
    Set the aperture to f/4(minimum) or better f/5.6 for best sharpness.
    Don't use Auto ISO, or bump up ISO too far. If the exposure is going to be too far past one minute, only then increase ISO. Higher ISO means more noise, which means less detail in the image.

    If you use Matrix mode, set the camera to -1Ev exposure compensation too. With this you want the majority of a black sky to remain as black as possible. Leaving the exposure to 0Ev on a black subject will force the camera to try to expose the black as more of a grey tone(not very good!)
    if you use spot metering, try -2Ev exposure compensation, as spot metering is a more concentrated metering method where it meters the scene around a much smaller area, that area is more likely to contain a darker black tone(that it otherwise would when you use Matrix Metering).
    So with this test exposure(and with you varying the exposure settings to suit your camera and lens combo) you will eventually arrive at a good exposure for the given conditions.
    In the exif data in this test exposure are all the settings required to shoot this scene with a level of exposure consistency, which you then switch to Manual mode(from Aperture Priority) and take multiple images to create a time lapse.

    if I shoot this same scene with my camera and lenses, because of the way digital cameras work, and the difference in the way lenses work, my settings may not directly translate into a good exposure for your camera.

    In the jpg image, the image is not focused on the stars. Nor is it focused on the roof guttering or the walls of the building.
    Set the camera to manual focus, and focus the lens to infinity. From memory, this would be all the way to the far left on the focusing collar on a Nikon kit lens, but you can confirm this with a simple test. Set the camera to about 30cm from any subject and rotate the focusing collar al the way to the right hand side of where you feel it 'stop' freely moving. At this point you can still keep rotating the focus collar, but there is more resistance beyond this stop.
    If the image is in focus or close too, then this is MFD(minimum focus distance) and as close as you can focus this lens. The extreme opposite of this focus setting is infinity. For stars, you want to focus at or close to infinity.

    As for how much time you want or need between each frame, this will depend on how many frames you've captured and how long you want the timelapse video to run. 100ms with 50 frames gives you 5sec of video. 100ms with 60000 frames gives you 1 hour of video. each 100ms is equal to 0.1s, so based on this time line and if you want 20s of video, you need 200 frames.
    There is no built in intervalometer in the lower spec Nikon cameras, you need a D200 or higher for that, and Nikon don't make any for them either. BUT!! you can get a few thirdparty remotes that do the same thing.
    Search Ebay for a Aputure AP-TR3N remote/intervalometer. They cost about $50 or so, and you set it up to automatically capture the required number of frames you want, and leave it be for as long as it takes to do this.

    So, if you want 200 frames at approx 1 minute each, you'll set the camera up to shoot in manual, attach the remote, and set the remote to capture 60sec exposures, up to 200 of them. This will obviously take 200 minutes to complete, so go watch a movie, make dinner, cuppa or surf Ausphotography for more info and images, or Ebay for more accessories to play with!
    There is no way to accurately get an exposure for more than 30sec on a camera(that I know of) without an intervalometer. Even the cameras with built in intervalometer don't have the same level of configurability as a dedicated remote does.
    Nikon D800E, D300, D70s
    {Nikon} -> 50/1.2 : 500/8(CPU'd) : 105/2.8VR Micro : 180/2.8ais : 105mm f/1.8ais : 24mm/2ais
    {Sigma}; ->10-20/4-5.6 : 50/1.4 : 12-24/4.5-5.6II : 150-600mm|S
    {Tamron}; -> 17-50/2.8 : 28-75/2.8 : 70-200/2.8 : 300/2.8 SP MF : 24-70/2.8VC


  3. #3
    Serial Truant.... phild's Avatar
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    You'll find a wealth of information on taking good astro photos at www.iceinspace.com.au, if your exposures are of any length you'll always get "blurring" (trailling) as the night sky rotates around the south celestial pole.

    There is a limit to the maximum exposure you can take on a fixed tripod without star trailling; from memory as a rough guide it's 600/FL so with a 24mm lens you can expect to do an exposure of around 25 seconds without significant trailling.

    To get better results up the ISO (that may not be an option on your camera without significant noise increase) and stack multiple images to get better results.
    Phil

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