Star Trails During Full Moon
My favorite time of the month to shoot star trails is during the first three days as the moon goes full. The cool light of the moon provides rich textures to surfaces and strong shadows that cast across the frame adding mystery and mood to the composition. A bright moon will also give color to the sky, contrast to the scene and again set a mood. Exposing the night sky in the light of the full moon is actually easier than photographing a dark sky. I find that overexposing works best keeping the histogram just to the left of center and then reduce the exposure to your taste during post production. Later in post production in the event I want to brush in a darker exposure in my foreground elements, increase shadows, or increase textures, I take a few shorter exposures both before and after the shoot. Depending on what I am photographing and my vision for the final image, I will use colored flashlights to add contrasting color(s) to one or more of the elements in the scene.
In this first image of the Charcoal Kilns in Death Valley National Park, I used a 2.5K candlepower flashlight with an orange gel to simulate fire light emitting from each kiln. Using the 2.5K light my wife went into each of the kilns lighting up the inside as I exposed each shot. After we had exposed each of the kilns I turned my concentration to setting my exposure for the star trails. I chose a 120 second exposure at ISO 200 and an aperture of f/8. Even though I was using my TS-E 24mm tilt-shift lens on my Canon 5D MkII I knew I needed depth-of-field to insure that my main elements of this composition would be in sharp focus from front to back, including the distant mountains. This is one of those shots that enforces the old saying, “be prepared”. When we travel we take not only what we know we need, we take a bunch of gear we might use, easy to pack and carry when you travel by car. I did not include Polaris in the frame as I composed and framed this shot mainly because I did not want Polaris to become a driving element in the composition. Not always do my compositions point towards Polaris, and not always is it a welcome element to be included in my compositions. It depends on the strength of the foreground elements and if the circular pattern of the stars around Polaris add to, compliment, or add to the diagonal of the frame. In post production my first step was to handle my sequence images and combine them into the finished star trails. I accomplished this first by opening my first image in Lightroom 4 adding 70% clarity, you can go 100% on the clarity slider but in this image it produced too many stars for me, I then adjust white balance and exposure to my liking. I then sync all the images, including my light painted images and export them as Tiff’s. Dr. Brown’s Stack-A-Matic is my stacking program of choice of which I load the Tif images from Adobe Bridge and Stack-A-Matic stacks the sequence into CS6 extended. Now all that needs to be done is opening the light painted images as layers into the star trail image, add a black mask to each layer and paint-in the orange fire from each of the kilns. I did spend some time cloning out the air traffic footprints, fortunately in this shot we were out of main air routes. The final step in my workflow is a trip through Perfect Effects 4 from onOne Software to bring out colors, textures and detail. For me, I rarely skip using onOne Software’s Perfect Effects 4 to enhance the tonality, contrast, colors and special effects that always boast the appearance of the final image. If you don’t have the option of layer building look at onOne’s Perfect Photo Suite 7, it is a great solution to layering with Perfect Layers, Mask, Effects and more, and will expand your Lightroom image processing workflow. If you use the standard version of Photoshop Dr. Brown’s Stack-A-Matic script will not work, however if you use “Load Files into Photoshop Layers” from Bridge you can us the “Lighten” blend mode once in Photoshop.
In this image of the old steam tractor at Furnace Creek Ranch I positioned myself facing northward and decided to include Polaris in the composition. I used the large tractor wheel and the circular starts around Polaris in juxtaposition including adding a diagonal element to the composition. This shot was also taken during the full moon cycle and provided ample light providing detail and texture to the old steel of the tractor. A red gel on my flashlight was used to light paint different areas of the tractor just in case I decided to add a stronger mood to the composition. My wife and I often spend time before or after the main shoot light painting the different elements just in case I want to change the mood during post production. In the development of this image a fellow photographer did the light painting working between several photographers in our group.
My post production workflow on this image was almost identical to the above, including the trip through onOne Software Perfect Effects 4 for a boost.
Shooting the stars during a bright moon can be challenging but the rewards are well worth the challenge. By understanding a few principles of moonlight you can ensure a successful night of shooting. The difference in exposure between just a quarter moon and a full moon is 3 1/2 stops of exposure. Add the bright moon during the months of May and June and you can add another 1/3 stop of light. A slight cast of whispy clouds covering the moon can cost you a half to a whole stop of light. Additionally, as the moon rises above the horizon and it’s brightness is effected by the earths atmosphere the intensity of the moon’s brightness may differ up to 5 stops or more until it rises in the sky. I have had an occasion where I wanted to start my sequencing as the moon rose making it difficult to set an exposure that I could live with throughout the sequence. In this situation I will shift my exposure towards the brighter moon and handle the exposure variance in post production. If I have any don’t do’s it would be not to change exposures after you start your sequencing as this will brighten or dim the stars depending on your exposure adjustment and will eventually show the preceding sequence of stars as brighter or dimmer than the continuing sequence. Another important principle is to make sure your exposures are long enough to expose the stars as they trail. What I mean by this is by using the 600 rule insure that your focal length and exposure will result in a star streak. Personally, I use 500 to divide my focal length into as I have found 600 to be a tad liberal in the results. As an example, I used a 24mm lens, therefore 500/24= 21, that’s a 21 second exposure before the stars begin to show movement. If we were shooting the Milky way during a dark sky we would be able to have a shutter speed of 21 seconds and still retain sharp stars. In our case we need to make sure our exposure is greater so we can create streaking stars. My rule of thumb starts at twice the maximum exposure and goes up from there to achieve my desired results. The lesson here is don’t wait for the new moon or a dark sky to shoot your favorite subjects in the shadows, unless that’s your flavor. Shoot them in the moonlight and see how moon light brings life into your compositions.