Back during a September evening the forecast for the night sky was clear for the Kansas City area. So I thought I’d head out to the Flint Hills on the Kansas side to a place called Teter’s Rock for some night photography. The Flint Hills encompasses a region in eastern Kansas and north-central Oklahoma. It features a band of rolling hills and grasslands with wide open skies. A place where in the spring you might see storms developing 50 miles away. In this area you can easily escape the light pollution of the city in search of a dark sky for star photography. While the dark skies are great for night photography, you have to really search for something to effectively use as s an interesting foreground element. Enter Teter Rock.
Teters Rock is a group of stones standing as a tribute to a man, James Teter, who owned the land where a small community developed around some oil fields. Of course the community is long gone and all that remains are these standing rocks on some high ground that represented what was originally intended as a guidepost for homesteaders searching for the nearby Cottonwood River. The original stones are long gone but the current day monolith was erected as a tribute to James Teter, while most any other sign of the former community is long gone. Teter Rock now offers a great foreground object to include in a composition while photographing the night skies of Kansas.
Arriving on site, I began to evaluate the area for possible compositions. The sun was just about to set so I caught a few quick shots of the setting sun through the openings of the rocks comprising the Teter monument. I then explored positions facing north to determine where to best set up to place the rock in relation to the North Star, which would be the center of rotation of my star trails. My initial objective was to plan for a length of time to take multiple exposures to later stack together to show the resulting star trails over Teter Rock. There are always small things to consider on the horizon, such as a flashing strobe on a distant tower, glow from a small town in the distance, should I position my camera closer to the ground for a lower perspective, and other considerations. The camera I had available to me this night was my Canon 5DSR. This camera is a great choice for landscapes because of its high pixel count, allowing for very detailed images. However, because of the higher pixel count it does not perform as well at high ISO settings often associated with night photography. But it is the only camera I had available at the time so I chose to use it to actually test its performance in these conditions.
When taking star trail images you won’t necessarily need to higher ISO’s such as 3200 or 6400. In fact I will often start out around f/4, ISO 400, 4min on a dark night without a moon. I might take a couple of test shots to fine tune my exposure. With desired exposure and composition determined, I set the intervalometer for no more than 4 min exposures and fire it off , sit back in my rag chair and enjoy a beverage and snacks, and just let it go. I had allowed for only a 1 sec interval between exposures and used a total of about 60 exposures to create the star trail shot above.
The crescent moon, which provided a small amount of ambient light, began to get low on the horizon as the night wore on. The brightest portion of the Milky Way, easily identified by its proximity to the constellation Sagittarius, was still about 15-20 degrees above the horizon. I could now reposition and try a few Milky Way shots above Teter Rock. Now this is when I really expected to run into problems with noise in my images because of having to increase my ISO. Using a Rokinon 24mm f/1.4 lens my strategy was to stay as low as possible on the ISO to mitigate the
noise and rely on the speed of the lens to capture the needed light. I knew that by using my 24mm and applying the 500 rule ( 500 / focal length of lens = max exposure time)I should keep my exposure time to no longer than about 20 seconds to render the stars as points of light in the image. Nonetheless, I decided to push the exposure to 30 seconds considering I kept my ISO at 1600 in lieu of the 3200 or 6400 I might have otherwise chosen using my Canon 5D Mark III.
All things considered, the images I came away with were quite acceptable after post processing, and to my surprise the noise was very manageable. You can see, however in the 100% magnification of the Milky Way image of why you should be mindful of your exposure time when your objective is to capture stars as points of light. While the image viewed at normal magnification looks acceptable, when magnified it clearly shows the elongated rice-shaped stars resulting from the earth’s movement over that 30 seconds. Where this would really become obvious is if you decided to make a large print. The lesson here is that you should always consider the 500 rule in these cases and even do a test shot and then magnify the result in your LCD to be sure your stars are both in focus and your exposure is within limits to produce stars as points of light.
The prime season in the Northern Hemisphere to view the Galactic Core of the Milky Way is from March to October, with best viewing between April and July. While the Milky Way is still visible throughout the year, the brightest portion of the core will be below the horizon from November to February.
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