Star Trails

edited April 2013 Posted in » Nikon D3100 Forum
Good Afternoon,

I've been reading this forum with interest over the past few months. I've taken a strong interest in photography for as long as I can remember. I've recently turned 30 and I've just bought myself my first DSLR, which I'm over the moon about. I'm interested in all sorts of photography, and for now I can only afford the 18-55mm kit lens, but I'm wondering if I can get some decent star trail results from it?

From what I can gather I will need a tripod (obviously) and a shutter cable. Am I right in saying that to get a decent result I will have to set the camera up on the the lowest aperture the camera will go (i.e f/4.8 with an ISO of 100)?

This has confused me, as the pictures I have seen have trees in the foreground that are fully in focus, but so are the stars! Am I being stupid? I just don't want to spend 2 hours of my time to find that I'm doing it wrong.


  • edited April 2013
    Howdy @badger8 - Welcome to the forum, good to finally hear from you!

    Yes, you can shoot star trails with your 18-55mm kit lens.

    Yes, for star trails generally you want to use the lowest available aperture f-number (f/3.5 at 18mm and f/5.6 at 55mm on your kit lens) and lower ISO's (100 to 800).

    This will allow you to take a long exposure while keeping noise levels at a minimum. There's a long technical reason for using this setup, but it might put you to sleep. ;)

    Depending on your foreground subject, you may opt to take a second exposure using a higher f-number (like f/8) to make sure it's sharp. For example, if you're shooting a city skyline that's well lit, then it makes sense to take the second exposure at f/8. If it's a distant mountain or tree line, then I would stick with your single exposure at the lowest available f-number.

    If you do end up taking that second exposure at f/8, you'll need to blend the star trails into the city skyline shot using Photoshop.

    Hope that all makes sense and happy shooting! :)

  • edited April 2013
    @moose - Thank you so much for the reply, I really do appreciate you taking your time to respond. You mentioned the potential second exposure in f/8. Is that just a single 30 second exposure?
  • edited April 2013
    Also, I've heard a few techniques. One technique is on bulb setting where you expose the photograph for 40 minutes! I've heard that can damage your camera due to over heating? Is it better to take x amount of 30 second exposures over a 40 to 240 minute period and then knit the pictures together? Sorry for all the questions.
  • @badger8 - Yep, the f/8 exposure would ideally be 30 seconds or less to keep noise levels down.

    Yep, you're spot can either take a single 15 to 30 minute exposure using "bulb" mode or you can take multiple 30 second exposures and then stitch them together using software.

    Just a heads up, the settings I mentioned earlier would apply to the single exposure. If you'd rather stitch images together, you'd actually have to increase the ISO (800 to 3200) in order to get the shutter speed down to 30 seconds.

    Bulb mode is easier because you end up with one shot versus multiple shots, however, like you mentioned the sensor can overheat if you go beyond say 30 minutes. In addition to the overheating, your final image will have quite a few hot pixels that will need to be photoshopped out.

    Taking multiple 30 second exposures is much safer for your sensor and will also result in less hot pixels. If you're looking for the best overall image quality, this would be the best route to take, however, it also requires the most skill.

    Tip...if you have noise reduction turned on, it will take another several minutes for the D3100 to process the image and apply the noise algorithm. If you do a single exposure I would leave it on. If you do multiple exposures, I would turn it off and reduce the noise using software instead.

    All the best!
  • I'm new to the camera world and very interested in star trails. After reading your instructions it sounds a bit easier than I thought. The method I will use is the multiple 30 second exposure mode and stitch together. I was told it might be a good idea to use a small rolled up piece of paper placed on the button then wrap a rubber band over it. This helps from your finger getting tired and also helps from moving the camera while on the tripod. Any thoughts to this theory?
  • edited August 2014
    I have a D3100, and any help on this topic would be great information being that I'm new to the DSLR field. Thank you.
  • edited March 2016
    How can I focus the stars with the D3100? I can't see the stars thought viewfinder. Thanks!
  • edited March 2016
    Hi @DWOODS,
    Forget the rubber band idea and purchase the IR remote control, it's relatively inexpensive. Push the button to open the shutter and then push again to close it at the end of your timed exposure; it's simple.
    @TRINIDADBRAVO, don't need to see them, just focus on infinity. Haha, the truth is out there!
  • edited March 2016
    Because the AF lenses can sometimes focus past infinity, which is worse than focusing a bit too close, I suggest you use Live View and zoom the view in until you can focus on something using manual focus. If you just can't see any stars, find the furthest horizon you can, and focus on that. Infinity will be in your depth of field. If you just crank the lens all the way to the stop, it may not be as sharp.

    Unfortunately, the D3100 does not use the infrared remote control. If you want a remote you will have to buy the plug in accessory. I do not know why Nikon dropped this feature on the D3100, which was present on the D3000 and reintroduced on the D3200, but there it is. I'd look for the plug in. You can use the hard wired MC-DC2, or (I think) one of the WU-1 variants. The hard wired one is likely to be the easiest.

    By the way, the rubber band might work if you do not have any other remote release. It may take some doing to arrange it right. I suggest that if you try this, you cap the lens initially, open the shutter and allow the camera to stop jiggling, then carefully uncap the lens. When you're done, simply shut the camera off, or if the rubber band apparatus gets in the way, recap the lens first.

    The biggest problem you'll have with the rubber band is finding one strong enough to push the button through both the focusing and snapping detents without slipping off. I think it will have to be a very wide and strong one, and even then it might require a piece of tape to keep from flying off. You might find a small nut or similar object works better than paper, because the button must go down a fair amount and stay down.
  • edited September 2016
    I took a picture for 45 minutes before and my camera is fine.
  • edited November 2016
    Hey Moose. I just purchased your cheat sheet and it's great! Question though..I noticed you had said on this thread to use an ISO of 100-800, but how come on the cheat sheet it says to use an ISO of 3200? Is this a mistake on the cheat sheet? I was thinking that a lower level would be better as well to keep noise down.
  • Hey @deezus - Great question! So the cheat card you're referencing is meant to "freeze" stars. This particular thread is for star trails, which uses an even slower shutter speed (minutes) to capture the movement of light a star makes as the earth orbits. Lower ISO's will give you slower shutter speeds, compared to higher ISO's which will give you faster shutter speeds (good for "freezing" stars).
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