Sunday, August 11, 2013

How to shoot the Milky way in a time-lapse, it's harder and easier than you think

Hi everyone.  I searched and search the internet for good information about how to shoot a time lapse of the milky way, surprisingly, I didn't find a whole lot of useful information.  Sure people are willing to share the settings on the camera, but to find the secrets of where to shoot, and how to shoot.

My guide to shooting night time time-lapse 

There are several things that have to come together before you try to go out and shoot.  The first is the phase of the moon.  You need the moon to not be out.  You can check the sunrise and sunset of the moon by your location at this site.

The next thing to check is the weather, check it here.  Make sure you check the cloud cover and the movement of the clouds at least a few hours before you go out somewhere.  You need the sky to be clear and you also need to know how much wind.  The reason for this is not only clouds, but the wind can kick up a lot of dust.  If there is a storm front coming in, chances are pretty good that along with that storm will kick up dust.

Ever here of light pollution?  Most of the time, if you live near any sort of city, you are going to have light pollution.  This is caused by all the lights that we keep on at night that end up reflecting and bouncing all over the place.  To find a place near you that has a dark enough sky, search here.

Ok, now we need to talk about equipment.  You need a camera, preferably a DSLR, with the ability to shoot long exposures.  How long? 10-30 seconds.  Most DSLR cameras can shoot up to 30 second shots in any mode.  You also need a wide angle lens.  The reason for this is because stars move.  If you zoom into a part of the sky, that smaller location will move more than looking at a whole lot of the sky with a wide angle lens.  You need a tripod and it needs to be stable.  The next thing is a intervalometer.  This is a device that will take a series of pictures at a specific interval.  I use Magic Lantern firmware which puts this capability in the camera.

That's it really.  There are lots of other equipment that can be used, but you don't need those things to take a good timelapse.

So I followed the steps above and this is location that I came up with:

It was far enough away to get out of most of the light pollution for my area and away from any traffic and close enough to drive within a couple hours.  The moon rise was 10:00 am so I didn't have to worry about the moon getting in the way, and the weather was mostly clear.  Because this is a timing thing that only happens every once in a while, I was willing to risk having a few scattered clouds.

Setting up

You need to find a location that has some amount of the earth in the shot.  You need this because without reference to something on the ground, it is hard for anyone watching to really see the amount of movement that is going on.  Also, because you are going to be shooting at a large aperture value (i.e. 2.8), you need to make sure that anything that is closer to you (like trees or bushes), isn't so close that you lose focus on the stars because of the depth of field.  Some of the more advanced shooters will increase the F-stop to allow for a larger depth-of-field to allow for this very thing.  You will then have to either increase the ISO, of increase the shutter speed to account for this.

I set the camera up, pointed at the horizon, and manually focus the camera.  Focus can be the most tricky part of setting up.  I usually end up turning on video mode, or live preview, and then pointing the camera at a star that is bright, and then manually adjusting focus so that the star is focused.  You may have to increase the ISO settings to above 3200 in order to really have the camera be able to "see" the stars.  If the stars are not bright enough, then you may have to resort to pointing at a man made light out in the distance to set the focus.

Next thing to setup is you camera settings.  Here are the ranges that you will want to test with:
Camera Manual mode
Lens: Turn off Autofocus
Lens width: 11mm - 24mm  (depends on crop or full frame camera)
ISO: 1600-6400
Shutter speed:  10-30 seconds
Aperture: F2.8 - F5.6
Intervalometer: Every 1-10 seconds (depends on how fast the shutter speed is)

Set the picture style to Faithful
Set the White Balance to 3200 K.  Do not leave it on Auto White Balance.

So take some test shots.  Keep the ISO as low as you can, but capture as much light as you possibly can. Try ISO at 1600, Shutter speed at 25 seconds.  In the camera preview mode, just remember that in really dark environments that the screen will look a lot brighter than the actual photo (or video frame).

Taking the sequence of shots

So now set the Intervalometer to take a picture every (shutter speed) + 1 second.  The length of the video will depend on how many shots you take.  Remember that every frame is only 1/24th or 1/30th of a second in video.  So for a 10 second video, you need 240 shots.  If you are taking 2 shots a minute, you need to shoot roughly 2 hours worth of shots.  This also may depend on the capabilities of your camera, but most should be able to handle it.  If you are using Magic Lantern on a Canon camera, this will work. I have tried using long exposure noise reduction and because it take quite a bit of time to process each frame in camera, I don't recommend it.  You can do better noise reduction in post. 
Obviously keeping the camera still is assumed.  If you have a lot of wind, you may want to make sure that you tripod is sufficiently weighted down to resist any movement.

That's it for the shooting part.  In my next blog post I will go over how to process the frames into a video.


1 comment:

  1. Great post Dave!

    Here are a couple of websites I use for finding dark skies...