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A Quick Introduction to Astrophotography

Were you ever mesmerized by the Milky Way when you looked up in the heavens in a clear summer night? That awe and even fear when marveling at God’s great creation is what makes astrophotography so captivating. However, it is also one of the most complicated and difficult types of photography. Therefore, this article is a quick introduction to its basics.

 

First, the most important condition for astrophotography is a clear night sky. Since longer exposure is preferred to let in more light, any small wisp of cloud passing by the frame can ruin the whole shot. A dry, cold night is also preferable. In the dark environment of astrophotography, one of the greatest challenges is to lower the noise. However, in a warmer night, the hot temperature can cause additional thermal noise. Furthermore, if the weather is humid, condensation on the lens becomes a problem, and cleaning it will be a painstaking process. Then, for the ideal location, it is best to find a place with minimal light pollution. The less the light pollution, the more stars can be captured in camera. The time of the year is also important. For example, the Milky Way is visible in the Northern Hemisphere from March to October and February to October in the Southern Hemisphere. Thus, the conditions in the Southern Hemisphere are more ideal since most of the Milky Way season is in winter. Lastly, the moon is a also crucial factor to the condition. When the moon is visible, it lights up the foreground, but its blinding brightness also covers up some of the stars that aren’t as bright. When there’s no moon in the sky, however, the stars are clearer, but the foreground needs to be manually illuminated or stacked in post-processing because it will be too dark. For example, the thumbnail picture was taken on a moonless night. While I captured more stars, the lack of light forced me to push the ISO (for light sensitivity) up to 20,000 even with an f/4 aperture and twenty second exposure, resulting large amounts of noise in the final image. Therefore, astrophotography has demanding conditions and requires detailed planning.

The most basic equipment for astrophotography is a DSLR or mirrorless camera and a tripod. Although some smartphone cameras do have astrophotography functions, their image qualities cannot compare with that of mirrorless or DSLRs. Then, a sturdy tripod is also required for the long exposures. For the lens choice, a wide-angle lens with the largest aperture possible is preferable. The small focal length is essential for capturing as much of the night sky as possible, and the larger aperture can significantly lower the ISO and reduce noise. For a moonless night, for example, the minimum aperture recommended is f/4. Any smaller aperture will result an unbearable amount of noise that ruins the image. Then, though not required, a shutter release can also be helpful when shooting star trails or just avoiding touching the camera when releasing the shutter. Lastly, warm clothes are essential for astrophotography. They might seem trivial, but shivering in pitch darkness for hours in the middle of the night is not quite a pleasant experience.

A picture with plain stars has no real points of interest, so foreground is essential to the composition. It adds to the story and functions as a comparison to the vastness of the night sky. However, the subject or foreground shouldn’t fill the frame, for most of the picture should be left for the stars. For example, in this picture, the foreground and subject are the campsite, and to attract viewer’s attention, it’s located on the bottom third. The rest of the image, though, is all dedicated to the Milky Way.

Exposure can be the trickiest part of astrophotography. The first component to determine should be the shutter speed. To let in more light from the stars into the camera, the shutter speed must be as long as possible. However, the stars will move in the sky as the Earth rotates. If the exposure is too long, the result will be a trail of light instead of a sharp dot in the sky. This is when the 500 Rule comes in. Simply divide five hundred by the focal length, and the result will be the maximum shutter speed possible without leaving noticeable star trails. For example, a twenty millimeter focal length gives a twenty-five second shutter speed. Then, the aperture should be as wide as possible, and the ISO should be increased until the exposure is right. While it is important to keep the ISO to the lowest to decrease noise, the widest aperture on a lens can often reduce sharpness. Thus, some photographers may choose to use a slightly smaller aperture and compensate it by increasing the ISO to sacrifice noise for sharpness. For example, they might use f/2 of a f/1.4 lens and increase the ISO one stop from 1,600 to 3,200 instead of choosing f/1.4 and ISO 1,600.

Since cameras can capture more detail in the night sky than the human eye can see, there’s more freedom when editing stars and Milky Way pictures. The result can be more imaginative and creative because without normally seeing the starry night sky with such clarity, it’s harder to tell if an astrophotography picture looks fake or not. Generally, increasing the contrast and the saturation can greatly enhance the Milky Way and stars, but photographers can enjoy the freedom to explore and find their own style when editing astrophotography images.

In conclusion, astrophotography is one of the most rewarding types of photography. After so much preparation and work, the results never fail to be breathtaking. It’s the kind of photography I enjoy the most, and I hope this article is enough to get you started.

 

Photo Credits: Charlie Su

Photo of the Month: Winter

Here are all the amazing winter themed photos from December’s Photo of the Month!

by David

by Eliana Kim

by Rachel Beth H.

by  Sophia Thuemmel

 

Next month’s theme is: Night Photography & Astrophotgoraphy

The photo does not need to include stars, any cool shots taken at night will work!

Please submit your photos with this Google Form: https://forms.gle/QKRNCx9ATwZg8tU67

The submission deadline is February 25th. If you have any questions, please let me know in the comment section.

19 Comments

  1. This sounds fun! I’m definitely going to do this!

  2. Ooo, really helpful and interesting article!

  3. Laura Cervantez

    Oh my goodness that is breathtaking.

  4. Thank you so much for writing this was extremely helpful! I have attempted astrophotography before, and gotten okay results, but now want to try again. One question, have you ever attempted a Star trail?

    • Awesome! I’m so glad that it can help! Astrophotography is the most magical photography experience there is, so definitely give it another shot! Yes, I did try taking a star trail pic before, but I didn’t get to learn how to combine the images in Photoshop. So I am very inexperienced XD. Star trail photos are way more complicated, and there are many different methods to do them. If you are interested, there are some really good star trail tutorials you can find on YouTube.

  5. Wow Charlie, that one picture is amazing! Great job! I did have a question though, what exactly is the ISO for? You had mentioned light sensitivity, but does it do anything else? Thanks!

    • Thank you! ISO is part of the exposure triangle that consists of aperture, shutter speed, and ISO. When the aperture and shutter speed can’t let in enough light to have the correct exposure, ISO needs to be increased. However, while increasing the ISO will make the photo brighter, it also increases noise in your image, which is the graininess that you see in some pictures. So photographers usually try to have the lowest ISO possible. If you are interested, here is an in depth YouTube tutorial about the exposure triangle: https://www.youtube.com/watch?v=iWfdxE1om6A

  6. Love these pictures, especially that one by David.

  7. these are beautiful *wipes tear* i can’t wait to see what pictures people submit next month 🙂 maybe I can find the time to enter a photo in too 😉

  8. Great article! & oh my goodness that picture is beautiful xD gjjj

  9. Do you know what your next topic will be on? I’m sadly not able to join this time because where I am I can’t take photos like these😢

  10. Will their be a photo of the month contest for every month of the year?

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