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How To Shoot Star Trails Print

In the October 2011 issue of Outdoor Photographer there was an article entitled "How To Shoot Star Trails", which is also available on line here.

 

This article was disappointing to me, because it doesn't really tell you how to shoot star trails. It was particularly disappointing to my son-in-law Duane Cassone, because he had written to the magazine offering his white paper on the subject for the magazine's consideration. Duane's white paper (which is on my site here) actually does tell you how to shoot star trails, and in this article I will do the same, with some of my photos as examples of what you can expect.
jt070a500
I took the photo above on September 29, 2011, in Joshua Tree, at Group Campground #5 in the Indian Cove Campground. It's a stack of 102 images, each 90 seconds long, taken at 1-second intervals, using a Nikon D3 with a Nikon 24-70mm lens set at 24mm, at ISO 200, f/2.8. The trails are circular because I faced the camera north to capture Polaris (the north star).
 
 
Now, before you grab your gear and head out, please read on so you'll have good background on what you need, what you need to do, and what you can expect.
 
 
With film, you can put a camera on a tripod, open and lock the shutter, and leave it for a few hours. You can't do that with digital gear because the sensors "bloom" and you could cause the sensor to overheat, damaging your camera, if left exposed for that length of time. Even if the camera survived all that, the resulting noise from an exposure that long would be nasty.
 
 
The solution is to take many, many photographs (say, 50 to 350) of short duration (20 seconds to 3 minutes) and use software to stack them together into one image. To do this you need to consider the following:
 
· Good camera gear. You need a DSLR, and a pretty good one, to be successful.
· Power. Your camera battery will probably take 50 or 60 photos, but it won't take 350.
· Stabilization. You will not be successful unless you have an excellent tripod.
· Wide angle lens. The wider the better, especially if you have an X-factor DSLR.
· Intervalometer. You program this device to tell the camera how many photographs to take, how long they should be, and how long to wait between photos. You can also program it to wait a while before starting.
 
 
Good camera gear.
If you already have a DSLR, that solves the first problem. If you don't, visit or talk to Mark Comon at Paul's Photo in Torrance for advice on what camera you need, based on your budget and skill set.
 
 
Power.
A fully charged battery should take 50 or so photos for you. This may or may not be satisfactory, depending on the direction in which you're shooting and the length of the trails you want to capture. I deal with the visual difference at the end of this article with some sample photos.
If you want to capture more than a battery's worth of photos, I suggest you buy a 5-In-1 PowerPack by Chicago Electric, which we have purchased through Harbor Freight for about $100. It's a cool device that will power two AC devices via an internal inverter. (It does a bunch of other things, too, but powering two AC devices is what sold us.) It looks like this:
powerpack
For each camera, you need an AC power adapter. For Nikon gear, you need an EH-6A external AC adapter. You plug the AC plug into the interverter AC receptacle on the PowerPack, and the other end into the AC input of the camera.
 
You need to charge the PowerPack for up to (and no more than) 36 hours before leaving home. If you're going to shoot on battery power, remember to take fully charged batteries with you and remember that cold weather depletes battery life quickly.
 
Stabilization.
You need a rock solid tripod so be prepared to spend some serious money. My Gitzo and Arca Swiss ball head combo was about $1,200, but I also have an Induro with an Arca Swiss style head that does a great job and was $550 at Paul's Photo. Talk to Mark about what you need, but remember—to get good quality, vibration-free photographs, the camera has to remain absolutely still. That isn't going to happen with a cheap tripod.
 
Wide angle lens.
For an X-factor DSLR, you should have something in the 14mm range; 24mm for a full frame sensor. You want to capture as much as of the sky as you can.
 
Intervalometer.
This is an advanced remote shutter release that you can program to shoot X number of photographs that are X minutes and/or X seconds in length with an interval of X seconds in between. You can also program a delay of X hours and/or minutes to begin after you press the Start button. Nikon and Canon make their own, and while you can buy a cheaper 3rd party version, I recommend you buy the item made by the maker of your camera. My good experience with my Nikon MC-36 units, and watching the bad experience of others with less expensive 3rd party units, tells me this is the way to go.
 
Some cameras have internal intervalometer settings, but from personal experience I can tell you that they don't work as well, aren't as sophisticated, can't be memorized, and will drive you crazy. Spend the money on a real intervalometer that's made for your camera.
 
The MC-36 programming looks like this when you first insert the batteries:
DELAY = 00:00:00
LONG = 00:00:00
INTVL = 00:00:00
N = 0
 
In the first three items, the first two zeroes is a number of hours, the second two zeroes is a number of minutes, and the last two zeroes is a number of seconds.
DELAY is for telling the camera not to start taking photos right away, but rather to wait for the number of hours, minutes and seconds you input. If, for example, you set it up for DELAY=02:00:00, the camera will wait for two hours and then start taking photos. This is useful in places like Joshua Tree where air traffic is significant until around midnight.
LONG is the length of exposure you want. If you set it up for LONG=00:00:40, you will be taking 40-second exposures.
 
INTVL is the length of time the camera will wait between exposures. If you set it for INTVL=00:00:01, you will have one second between exposures, which is what I use.
N is the number of photos you want to take.
 
So, a set up like this:
DELAY = 02:30:00
LONG = 00:01:30
INTVL = 00:01:31
N = 200
 
will tell your camera to wait 2 ½ hours before starting, take exposures of 1 ½ minutes, wait one second between exposures, and take 200 exposures.
 
Procedure for capturing images
I'm giving you my procedures—but understand that I'm a Nikon guy and this is what I do. You should experiment with different exposure lengths, ISO settings and f-stops as you get used to the processes.
 
· Set camera on tripod.
· Remove any filters, including skylight (they may cause ghosting).
· Leave lens shade on.
· Plug an MC-36 intervalometer (or equivalent) into the 10-pin connector and program it for the desired delay, length of exposure, and interval between exposures.
· Plug EH-6A AC adapter into camera AC input, and plug into inverter AC receptacle on PowerPack.
· Turn long exposure noise reduction OFF. (Mine is always off—I use Dfine to clean up noise.)
· Put a bubble level in the hot shoe and level the camera as necessary. (You may not have a horizon to work with.)
· Set ISO. The lower the setting, the less noise you'll have to clean up, but we think that 400 is ideal.
· Turn autofocus OFF.
· Set camera to Manual operation (and set lens to Manual, as necessary).
· Set aperture to f/4. We've found this is optimum.
· Set focus to infinity.
· Set shutter speed to BULB.
· After setting composition, close the viewfinder shutter. If you can't do so on your camera, consider taping over it.
· Start the intervalometer, start the inverter on the PowerPack, and go to bed.
 
Putting the images together
We use a marvelous program called Star Trails that was written by Achim Schaller in Germany. He gives it away and it's available for free download here (http://www.startrails.de/html/software.html) to anyone. There are a number of advantages to using this program, which include:
 
1. The ability to remove single images from the stack. This can be important of you have an airplane fly-by in one or two frames leaving a red trail that you want to remove.
2. It sets up the stack, including the blank frame, so no other action is required of you.
3. It will also produce a time lapse video from your images if you desire.
 
It only works with JPEG files, so if you shoot RAW files (as I do) it's wise to process them all in Lightroom to adjust white balance and then export them as full resolution JPEGs to a separate directory. Then, open Star Trails, and open all the JPEGs you saved to begin.
 
Depending on where you're shooting, there may be a flight path and therefore airplanes in your field of view. Starting the sequence late (after 1:00 a.m., for example) will reduce the number of flybys. In the Startrails program, you can remove frames that have airplanes, but the results will give you more "Morse coding" in the trails.
 
What kind of trails do you want?
The circular trails that surround the north star are really cool and are what people usually want to capture. But pointing in other directions can also give you great results. Pointing south can give you concave and convex trails that are pleasing to the eye. Including a foreground element of some kind will provide scale and make the image more interesting. Below are some examples for you to consider. Feel free to send me an email (link on the home page) if you have any questions.