Can the Light of a Moonless Night Sky Be Used to Take Photographs?
Photography is a vast and diverse field, encompassing a multitude of techniques and technologies. In the realm of astrophotography, the allure of capturing pinpricks of light from the night sky can be deeply captivating. While the presence of the Moon enhances starlight visibility, it is possible to take breathtaking photographs under a moonless night sky. Let’s explore the technicalities, equipment, and techniques required for this fascinating form of photography.
Understanding the Challenges
Photographing stars with a long exposure on a dark night without the Moon is feasible but presents unique challenges. Under such conditions, the limited light available can be almost negligible when compared to even moonlight, let alone sunlight. However, with the right equipment and techniques, capturing the celestial bodies in the night sky can yield stunning results. A long exposure is essential for allowing enough light to reach the camera sensor.
The Role of Fast Film and Long Exposure
In the era of traditional film photography, fast film played a crucial role in capturing the starlight. Fast film is designed to be highly sensitive to light, allowing it to capture images in low-light conditions. The sensitivity of film is measured by its ISO (film speed) number, which represents the film’s sensitivity to light. Higher ISO values allow the camera to capture more light, making them ideal for astrophotography.
Historical Context and Evolution
Traditional film came in a variety of sizes, sensitivities, and emulsions. Different films were optimized for specific purposes, with some prioritizing convenience and others focusing on quality. For example, color, black-and-white, infrared, and x-ray films each had their unique characteristics. The smaller number on a film canister typically indicated the number of frames it could hold, while the larger number was the ISO (American Standards Association) rating, indicating the film’s sensitivity to light.
Photographers in the past often used ISO 100 or 200 film for daytime photography, while indoor scenes did well with films rated up to 400 ISO. Flash photography typically required even slower films due to the graininess that could result from using higher-speed film. A longer lens admits less light than a shorter one, and a larger film size generally captures higher resolution images. Transparency film often featured finer grain, allowing it to capture more sensitivity to light while maintaining good image quality.
The Emergence of Digital Sensors
The development of CMOS sensors in the late 20th century was a game-changer for astrophotography. These sensors were first used in space probes by NASA and later found their way into consumer electronics, including cell phones with built-in cameras. These digital sensors have significantly improved the ability to capture the faint light of stars, allowing photographers to push the boundaries of what is possible.
For instance, the image below was taken using a Canon Powershot GX-9 II under the illumination of a low-wattage landscaping light in Houston. The high ISO setting and long exposure allowed the camera to capture a bright sky, even in an environment where it was never truly dark. The use of the camera's flash resulted in a clearer image with a darker sky, as the exposure was shorter.
[Image: Owl illuminated by a low-wattage landscaping light]Techniques for Capturing Starlight
To capture the stars in the night sky, a digital camera with a high-sensitivity sensor is essential. A long exposure is crucial, as it allows the sensor to collect more light. This technique can also capture the movement of stars, creating the impression of trails in the sky. Here is an example from an energized introductory video, showing Devils Tower in Wyoming:
[Image: Still from Patreon intro video showing Devils Tower with the Milky Way in the background]Additionally, capturing landscapes illuminated by starlight requires long exposures, as even the slightest illumination can be captured. Sometimes, the landscape itself is illuminated by nearby towns or cities, making it appear dark in the final image. This is evident in the image below, where most of the illumination comes from the town:
[Image: Landscape illuminated by town lights, with stars visible in the sky]Long Exposure Techniques
The desire to achieve a truly moonless night sky photograph often leads to the use of long exposures. However, the stars can appear to move due to the Earth’s rotation, creating a phenomenon known as star trailing. To combat this, photographers can use bright objects like meteors as additional light sources, as demonstrated in the image below:
[Image: Stunning full-color image of the Perseid meteor shower, merged from 23 individual exposures]Some photographers, like Beth Moon, have captured ancient trees under the light of moonless nights, using starlight as the sole illumination source. These images often require extremely long exposures, as shown in the image below:
[Image: Ancient tree illuminated by starlight alone]These stunning images serve as a testament to the power of patience, dedication, and the right equipment. By combining multiple exposures, photographers can create images that would be impossible to capture under even the faintest moonlight.
Conclusion
Photographing in the moonless night sky may seem daunting, but with the right techniques and equipment, it can be a rewarding experience. Whether using fast film or modern digital sensors, capturing the beauty of the night sky is a journey into the vast and wondrous realm of astrophotography. So, the next time you find yourself under a moonless night sky, grab your camera and start exploring this beautiful and vast cosmos.