The August 2015 Perseid Meteor Shower and Milky Way – Astrophotography Over Rural San Luis Obispo County, California
For night sky enthusiasts and photographers alike, the August appearance of the prolific Perseid meteor shower is a highly anticipated event. The Perseids are associated with the comet Swift–Tuttle and are named for the constellation Perseus, the point in the heavens from which they appear to radiate. The Perseid cloud is a debris stream that spreads out along the orbit of Swift–Tuttle, consisting of particles thousands of years old, jettisoned by the comet as it travels on its 133-year orbit.
The Perseids are visible beginning in mid-July each year, peaking in activity from August 9–14, depending on the location of the debris stream. During the peak, these streaking meteors – or so-called shooting stars – can reach a rate of 60 or more per hour. This year, in August 2015, a photographic trifecta occurred, as the meteor shower peak nearly coincided with a new moon, ensuring dark skies for perfect viewing conditions. In addition, the Milky Way was highly visible in the sky during the same time. So the environment was ripe for sky watching and astrophotography.
On Wednesday evening 8/12 into the early morning hours of Thursday 8/13, I went out with two photographer friends to shoot the Perseids and Milky Way. After some careful planning with photo apps such as Photo Pills and The Photographer’s Ephemeris, we chose a location off Shell Creek Road in rural east San Luis Obispo County, CA, a popular area for photographing wildflowers in the Spring. This area is approximately 30 minutes east of Paso Robles and is known for its oak-studded rolling hills. With no city lights nearby to contaminate views of the night sky, the darkness seemed to cloak everything but the heavens. Thankfully the skies were clear and the weather perfect, something a photographer can never count on when doing night photography.
The Milky Way was predicted to arc over the area in a northeast to southwesterly direction, and it did not disappoint. The Milky Way was simply brilliant and stunning. The constellation Perseus rose in the northeast, and the sky show was spectacular. We thoroughly enjoyed seeing the many meteors whiz by. Some were dark orange like fireballs, while others were bright white or bluish. The meteors came from all directions, but were difficult to capture on camera, necessitating many exposures over several hours. The combination of the Milky Way and Perseids dancing across the heavens was a sight to behold. Mother Nature at her best.
In the first image at the top of the post, It Came From Above, I was lucky to catch three meteors, which can be seen in the middle of the photograph surrounding the Milky Way. In addition, if you look closely at the lower left portion of the big oak tree where one of the branches seems to touch the hillside, you can see part of an orangish meteor. In the second image above, Another World, I caught two meteors, which can be seen on the left side, right above the hill. For this image, a small amount of light painting was applied to the foreground area.
In the third image above, 10,000 Light Years From Home, I turned the camera around in the opposite direction and pointed it straight north toward Polaris – the North Star – in order to capture circular star trails. A bit of light painting was applied to the foreground area. This image was a single long exposure of around 15 minutes at ISO 200. Had we not been so pooped out, I would have taken an even longer exposure to get more intense star trails. Or I would have taken a set of shorter exposures and then stacked them together to get the star trails.
The images were taken with my Nikon D800 and Tokina Pro FX 16-28mm f2.8 lens mounted on a tripod, using a Nikon cable release/intervalometer. All the images were processed in Adobe Lightroom.
One of my favorite nearby places to photograph is a special locale known as Chapel Hill in Shandon, California, about 15 miles east of Paso Robles off Highway 46 East. Chapel Hill is a lovely, private Catholic chapel perched high on a beautiful vineyard-studded hill built by the late famous Shandon resident (Judge) William P. Clark, Jr., former Deputy Secretary of State, National Security Advisor, and United States Secretary of the Interior, who worked with former President Ronald Reagan, his close friend and confidant. Chapel Hill has spectacular views of the surrounding countryside and is located amongst the hills of Clark’s massive private ranch off McMillan Canyon Road. Anyone can make the journey up the hill from the dirt parking lot below. Getting to the top of Chapel Hill is another matter, however, with a very steep climb. The incredible views from the top are well worth the climb with or without your camera equipment. There are beautiful grapevines along the path to the hilltop.
During this outing I wanted to capture star trails in the night sky over the chapel, as it is pointed nearly straight north at Polaris and therefore perfect for producing concentric star trails using star stacking software. The image was shot with my Nikon D800 using an intervalometer (and tripod, of course), and is comprised of 30 individual Camera RAW shots at 150 seconds each (with one second in between each shot), at f4.0, ISO 200 and 24mm. A bit of light painting was used on the chapel due to the foreground darkness (although it could have used more, especially on the chapel’s cross). Not bad for a first attempt at using new star stacking software; however, I hope to return and reshoot the scene with my ultra-wide angle Tokina AT-X 16-28mm f2.8 Pro FX lens in the future. I had mistakenly grabbed my 80-200mm Nikkor lens instead in my rush for the door.
For those of you who are unfamiliar with shooting star trails in photography, the earth’s rotation turns star points into star trails when camera exposure times roughly exceed 30 seconds (sometimes less depending on the focal length of the lens). If the camera is pointed towards the North Star (Polaris) and multiple consecutive exposures are taken – then blended together using star stacking software – gorgeous concentric star trails result that revolve around Polaris. For this composite, I used Lightroom and Photoshop for post-processing, and did the star stacking using Markus Enzweiler’s awesome StarStaX software. StarStaX is not only excellent but is freeware; however, donations are requested and well-deserved.
If you instead wish to capture sharp crisp stars (star points) or the Milky Way in the night sky, you will need to shoot at a very high ISO and wide aperture for less than 20–30 seconds, depending on the focal length of your lens. Unfortunately, the higher the ISO the more the camera noise. So there is a definite tradeoff. The general rule of thumb in determining the maximum length of exposure time to render star points versus trails is 600/lens focal length in mm. This means if you are shooting with a 20mm lens, your exposure time needs to be 30 seconds or less to obtain star points. Above 30 seconds exposure time you will begin to see movement in the stars.
If you are shooting with a 50 mm lens, the maximum exposure time would be around 12 seconds, not nearly enough to shoot at a lower ISO to avoid noise. Or enough time to do adequate light painting. Obviously the shorter (wider) the lens focal length, the more exposure time is available to shoot star points which is helpful to avoid noise at higher ISOs. In addition, you will capture more stars in the sky with an ultra-wide angle fast lens. Note that with some full frame (FX) DSLR cameras such as my Nikon D800, a more conservative formula to use is 500/lens focal length. Using this more conservative formula, a 16mm lens would allow for around 31 seconds of exposure time before rendering star streaks.
Below is a short (14 sec) timelapse video I made from the individual, unprocessed still images used to create the star trails in StarStaX. Since each of the 30 shots were 2.5 minute exposures, you will see the sky, foreground and chapel darken over time as the night progressed. This demonstrates the movement of the earth as it rotates and how the star points appear to move from one location to another in the night sky, morphing into streaks or trails. Of course that is because the stars are being viewed from the ground, which is actually in motion. Note that this timelapse has been purposefully slowed down for demonstration purposes.
If you look closely around the 8 second mark, you will see a big challenge to night sky photographers: a plane streaking across the sky, which needed to be cloned out in post-processing. Minimizing this challenge is one of many advantages to shooting multiple exposures and then stacking them, as opposed to shooting one very long exposure. In addition, noise becomes an issue with long exposures as the camera sensor heats up. For more information on and images of Chapel Hill, see my other posts Starry Starry Night, Photo Excursion to Chapel Hill and Chapel Hill.
If you are interested in learning how to photograph the night sky, I highly recommend the wonderful eBook Shooting Stars: How to Photograph the Moon and Stars with your DSLR by Phil Hart, winner of the 2012 David Malin Astrophotography Award. Shooting Stars, a 129-page eBook with a printable field guide, will show you how to shoot your own stunning images of the moon and the stars with just your digital SLR and a tripod. Another excellent book written by James Martin and elite Canon Explorer of Light Jennifer Wu is Photography Night Sky: A Field Guide for Shooting After Dark.