If you take night photos, you’ve just doubled the amount of time you can take photos. I’ll tell you how I created these star trails photo through “stacking”, or combining multiple images into one. It’s not the only way. There are even easier ways. But this method gives you a lot of control and quality that dedicated star trail stacking programs don’t seem to offer.
Above: Temple Tree Star Trails. While this also uses the stacking process described here, I’ve also altered the opacity of the layers to give the star trails a comet-like effect. I will describe this in a May 2013 post. Zion National Park, Utah. This photo was selected as one of the Daily Dozen by National Geographic.
This photo was taken in Trona Pinnacles in the Mojave Desert in California, and was featured in a number of places, also winning the Los Angeles Times Photo of the Year in the Travel Section as an Editor’s Choice. It is a 50-minute exposure in total, stacked in Photoshop CS4.
Noise is the enemy of night photography. Keeping your shutter open for long periods of time is more likely to introduce noise. Stacking photos was originally developed as a technique in digital astrophotography to reduce noise, but of course, as more artistic photographers can use this technique too.
WHAT YOU WILL NEED
* A camera that with a manual exposure mode that lets you set shutter speed, aperture, and ISO with a Bulb Setting, or at the very least, allows you to set the shutter speed for 30 seconds, and preferably, a camera that shoots in RAW so you can control the processing (but if you can’t, shoot at the highest resolution JPG setting you can). Most DSLRs will fit the bill, but there are some compact digital cameras that also have these features.
* Lots of batteries for your camera. Long exposures can really wear down your batteries.
* A remote cable shutter release so you don’t shake the camera by pressing the button
* A tripod for keeping the camera as still as possible. I used my Dad’s heavy 1970s Sears tripod, which was hard to lug around and got really cold on winter desert nights, but finally got a Feisol carbon fiber tripod with a Photo Clam ball head, which is easier to set up and adjust.
This is a star trails, showing the celestial movements of the stars over Borrego Springs, CA. The total exposure is 27 minutes, using stacked photos, each of them 30 seconds in length. The horse sculptures were created by sculptor Ricardo Breceda.
WHAT’S NICE TO HAVE
* A wide-angle lens. While you can photograph star trails with just about any lens, a wide angle shows a broader view of what we are seeing, are a bit more forgiving about focusing (which is challenging in night photography), and shows more curvature in the star trails, something I absolutely love. But I’ve shot with other lens too. Depends on what you are going for.
* a red LED light so you can fiddle without adversely affecting things or experiencing glaring white light.
* An interval timer for your camera. Really, this should be considered equipment that you need. Why? It’s difficult to create a set of images that can be stacked without one of these due to not being able to time your exposures accurately enough over a long time manually. I’ll tell you how I got around this even though it’s probably not considered ideal. Also, since I wrote this in June 2012, I’ve also begun using an app called TriggerTrap, which runs in Android and iOS smartphones, using the smartphone as an intervalometer, among other things. It’s super easy to use.
* Mag lights, flashlights, LED lights, ProtoMachines LED2, or other light sources for light painting the foreground. Sometimes you might not want a super dark foreground. Consider “light painting” the foreground! It’s also a lot of fun and passes the time quickly! But having the foreground as a silhouette can often be quite striking as well. You’re the artist. It’s your call!
Above: Trinity Star Trails. While this uses the stacking process described here, I’ve also altered the opacity of the layers to give the star trails a comet-like effect. I will describe this in a May 2013 post. Joshua Tree National Park, California.
SCOUTING THE LOCATION
I look for an interesting foreground. Star trails are not so interesting artistically by themselves, in my opinion. Like any photo, it should be about the overall composition.
I often like to face the camera north. This is because I like to capture the star trails swirling around the north star. Polaris, or the North Star, remains stationary and in a star trails photograph, the stars will appear to swirl around it. If you’re in the Northern Hemisphere, locate the North Star by finding the Big Dipper, the grouping of seven stars that looks like a ladle. The two stars forming the end of the Big Dipper’s bowl point directly at the North Star. The North Star is the end of the handle of the Little Dipper. Or you can use your iPhone GPS or a compass.
I try to make sure that if the moon is out, it won’t shine into my lens for the duration of my shot.
And finally, I try to choose a location far enough from the road so cars wouldn’t shine their headlights on my foreground or be interrupted.
And it probably goes without saying that the less “light pollution” from light sources, the better you can see stars. You can scout locations in the United States from this website, the Dark Sky Finder.
I use my Feisol tripod, double-check to make certain everything is tight and locked down, and if around sand, jam it down into the sand hard. After all, we certainly don’t want any movement from the camera. If it’s windy, I’ll hang one of my packs on the center hook to give my setup more weight.
FOCUSING IN THE DARK
There’s a few ways to focus. One obvious way is to set up while it’s still light and use your Auto-Focus. You can also take some photos now and blend in the twilight photos with your star trails. If you focus while it is dark, you may shine your flashlight at the foreground object, use your AF as usual, then switch to manual so your camera doesn’t “hunt”.
And yet another way is to try and find true infinity on your lens. This method is excellent for getting the stars as sharp as possible, and is particularly good if the foreground elements are 20 feet (7 or 8 meters) away. However, each lens is different, and finding true true infinity may sometimes not even be on the “infinity” mark, or may be on different parts of the “infinity” mark. If using this last method, you may need to take multiple photos and zoom in on them on your LED to determine what is the sharpest, or use Live View and zoom in on the stars if you can to make certain they are the sharpest.
Remember before I told you that an interval timer should probably be considered essential equipment? Sure. But they can also be expensive. Getting a good one can often be $100 or $200. At any rate, I didn’t have one, but needed to time exposures accurately so the exposures would be consistent. What to do? Well, it turns out that when my remote cable shutter release is locked and the camera is not in Bulb Mode, the camera will keep shooting over and over if set to continuous drive mode. So I set my camera for 30 seconds, the longest shutter speed it allows before Bulb Mode, then lock the shutter release. (note: since I wrote this in June 2012, I’ve also begun using TriggerTrap, an app that runs in iOS and Android smartphones, using the smartphone as an intervalometer, trigger, and other things. It’s super easy to use, connecting to the camera with a dongle. Google this for further information).
Click….click….click….click….time to lay back, look at the stars and soak in the beauty of it all.
I also make sure to shut off the in-camera long exposure noise reduction when shooting for “stacked” photos. Why? It takes the same amount of time to reduce the noise in the photo as the exposure. In other words, if I shoot for 30 seconds, the camera takes an additional 30 seconds to apply noise reduction. This would leave gaps in the star trails. But as I mentioned, the process of stacking photos reduces the amount of noise, so I didn’t get worked up about this.
If you’ve been reading this blog, you know that I love this Michael Kenna quote: “Getting photographs is not the most important thing. For me it’s the act of photographing. It’s enlightening, therapeutic and satisfying, because the very process forces me to connect with the world. When you make four-hour exposures in the middle of the night, you inevitably slow down and begin to observe and appreciate more what’s going on around you. In our fast-paced, modern world, it’s a luxury to be able to watch the stars move across the sky.”
If you wish, you may also take a dark frame image by putting my lens cap on to make sure no light was coming in and took one photo. Why? Noise reduction. In Photoshop or another photo editing program, you can add the dark frame photo as a new layer, then change the blend type to “difference”. Next add your foreground image as a layer, create a black mask and paint in the foreground, and adjust to taste. I haven’t really used this, but it’s something you could do if you find it helps.
Above: Big Bend Star Trails. While this also uses the stacking process described here, I’ve also altered the opacity of the layers to give the star trails a comet-like effect. I will describe this in a May 2013 post. Zion National Park, Utah.
5 STEPS TO STACKED STAR TRAILS SPLENDOR!
Now, back in the digital darkroom, it’s time to make our star trails photo come to life! Here’s how I’ve been processing my photos in Photoshop CS4 so far.
1. PROCESS AND CONVERT NEF FILES TO TIFF: I typically batch-process RAW (NEF) photos in Nikon ViewNX 2 and output them all to TIFF 16-bit files, but of course, process your RAWs however you need to. I select all the photos, apply adjustments and settings, processing them all the same, sharpening them slightly and adjusting the white balance. I also rename any photos that had something different about them, marking them if they have a line from an airplane to call attention to it later in the stacking process so I could spot them and adjust or erase them if I wish.
2. CREATE STACK: In Photoshop, I select File > Scripts > Load Files Into Stack, and then select my PSD files I wanted to stack. I do not have Photoshop Extended, which has a “Statistics” option that offers greater variety). This results in an absurdly large file of something like 6G. When I do this, I have many PSD files that are 73-77MG each, after all! Relax. The computer may take a while to process this large of a file.
3. ADJUST LAYERS: In the MODE PANEL WINDOW (which is the window that controls the Layers, etc. at the bottom right), I change each layer from “Normal” to “Lighten” or one of the other ones (such as screen, color dodge, linear dodge, lighter color). You can also create a Photoshop Action to do this if you wish to lessen the chance of carpal tunnel! I use a Layer Mask and use the Brush Tool on the left to brush away anything I do want.
4. OUTPUT IMAGE AS FLATTENED HIGH-RES TIFF: After adjusting layers to your artistic satisfaction, you can output the image as a flattened image with no layers, preferably a high-res TIFF. From here, you can perform the usual adjustments if you wish, such as dodging, burning, sharpening, or final color adjustments if you wish, just like any other photo.
5. SAVING THE ORIGINAL .PSD LAYERED FILE: I’m going to mention this in case it applies to you. Photoshop CS4 cannot save this large of a group of files if it’s over 2G, so I chose to merge the layers (Image > Merge) to keep it. I merged four layers at a time. Since each was a 30 second exposure, merging four layers equaled 2 minutes, still rather manageable, reducing the file size to a quarter of it’s original size of 6G.
StarStax: Since I originally wrote this in June 2012, I’ve begun using StarStax, freeware for Mac OS X, Linux, and Windows. It creates star trails with comet-like tails, and offers gap-filling. It’s also absurdly easy to use. Take the photos as described above, throw ’em in here, and see what it can do. I now try this first, and if I can’t produce what I am envisioning, then I go to Photoshop and stack using the process described above.
If you have suggestions for how I did it, please leave a comment! I’m not approaching this as an authority, but more as a photographer who has now done it and is really happy with the results! If you use this technique from reading this blog, please feel free to leave a link to your star trails photo in the comments section! Thanks so much for reading!!
EXTRA: Just because I’m utterly sweet, I am going to show you with an example of a 33-minute exposure at ISO 200, f/11. You can clearly see the noise. The discoloration is due to the camera sensor overheating since I was shooting on a hot night. This is what stacking can avoid:
The evening was fairly warm, which accounts for some of the overheating of the sensor. Some photographers put ice packs wrapped in plastic or other things to prevent the sensor from overheating and thus creating extra noise and discoloration.
The photo below is much better, a far less noisy 14-minute f/2.8 ISO 200 photo:
Single exposures can be beautiful. It has a lighter ethereal quality that the stacked photo doesn’t have, and also doesn’t have noise issues due to the shorter exposure time.
Noise is the enemy of night photography.
There have been times in which I’ve been able to get away with longer exposures, having done 34-minute exposures without much of an issue in colder weather. Like anything else, there are many variables.
I hope this helps. If you have questions (or corrections), please ask in the comments section below! Thanks for reading!!!!
Equipment: Nikon D7000 and a Tokina 11-16mm f/2.8 lens for Trinity Star Trails and the photos from Zion National Park. Nikon D90, Nikon 18-200mm VR II Nikkor Telephoto Zoom Lens for all else.
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