how to take successful photos of a starry sky?

Who has never marveled at the splendor of a starry sky on a beautiful clear night? Milky Way, stars, planets… Astrophotography gives us the opportunity to create stunning images that remind us how small we are in the universe. Although this practice of photography presents some challenges, it is nevertheless accessible to everyone. With little equipment, good advice and a healthy dose of observation, star photography is within reach. Take out your camera or smartphone and look up to the sky.

What equipment to photograph the sky at night

The challenge for the photographer who seeks to capture a starry sky is to bring together all the elements that will allow him to capture the faint light that the celestial elements reflect, in the middle of the night. For this, we need some material to be selected carefully.

A camera

Before getting started with astrophotography, you of course need a camera. Luckily, you don't need to own a high-end mirrorless camera, any type of camera will do. A body with a full-frame sensor will of course be able to capture more light, but an APS-C body is more than capable of giving good results.

Choose a camera that supports RAW format. This type of file, richer in information, gives photographers more flexibility when retouching their photos. In the case of star photos, this is essential.

A suitable objective

To this, let's add an objective, but not just any objective. Investing in a good lens is essential, whatever the type of photography you wish to practice, this is even more true in astrophotography.

To go further
Photo lenses: understand everything about the different optics for your camera

Indeed, it is a crucial element in the success of a photo session of the celestial vault.

Opt for a lens with a wide focal aperture: f/2.8, f/1.4, etc. A large aperture is necessary to capture as much light as possible. For this type of practice, the chosen lens must open to a minimum of f/4. In short, the larger the aperture, the better the photo will be.

As for the focal length, a wide-angle lens (16 mm, 24 mm) will be preferred to integrate tangible elements into the sky and therefore compose a real landscape: trees, a building, the relief… So many visual cues which give a real dizzying dimension to the starry sky.

Note that the lens used must be equipped with a manual focus mode. Finally, look for a lens renowned for its optical quality, with little distortion and good correction of chromatic aberrations. High-quality lenses produce sharper, more detailed images with fewer visual defects.

Additional equipment

Equip yourself with a good tripod or, failing that, a reliable support. To ensure flawless stability and therefore perfect star capture, the camera must be still when shooting.

A flashlight or headlamp is a very useful accessory for installing your housing and making adjustments without fumbling in the dark. To be turned off before any triggering so as not to pollute the images.

As an option, provide a remote control to trigger remote shooting. It is essential to avoid any movement when triggering which would cause the camera to move, even by an iota. Failing that, it is possible to configure the self-timer on your camera or trigger it remotely via the manufacturer's application, via Wi-Fi or Bluetooth, and thus avoid any camera shake.

The technique for success in astrophotography

To take successful photos of stars, it is above all a matter of being attentive to your environment. Although stars are everywhere around us, they do not show up in all circumstances.

Choose the right place

The number one enemy of astrophotography is light pollution. Photographing the night sky requires moving as far away as possible from areas where human activity is concentrated, otherwise you will see a yellow/orange halo appear on your photos, and very few stars. Favor nature or, better yet, altitude, to capture a sky free of any stray light.

Choose the right time

It is preferable that the weather is good. So, opt for a clear night. Also monitor the lunar cycle: a large round moon is a particularly luminous element whose impact is not negligible. It acts like a spot of light and can spoil a photo session, if it is not the subject.

Settings to know

Once the equipment and conditions are in place, all that remains is to configure the camera. To do this, here are the correct settings for photographing the stars:

• Set your camera to manual mode so you can change settings to your liking;
• Switch your lens to manual focus and set it to infinity. Likewise, you can use the body's LCD screen to focus on a star;
• set the aperture to the widest possible value (f/2.8, f/1.4, etc.);
• set a long shutter speed, for example 15 seconds. This long exposure will require some adjustments depending on the light conditions and the aperture of your lens, so don't hesitate to test different exposure times to find the one that works best;
• set the ISO to a high value to capture more light. Each camera has its limits in terms of ISO rise and noise, so it's up to you to adjust the value according to your hardware.
• Use your remote control or set the self-timer to 3, 5 or 10 seconds.

Frozen stars or shooting stars?

An additional parameter must be taken into account when photographing the stars: the rotation of the Earth. In fact, the longer the exposure time, the more this rotation is visible in the image. The stars will then no longer be fixed points, but luminous lines.

To obtain maximum sharpness, you can rely on the rule of 500. To put it simply, it involves making a calculation which indicates the maximum exposure time depending on the focal length used. For example, if you have a 24mm lens, the calculation is: 500/24=20.8. The maximum exposure time to obtain very clear stars will therefore be 20.8 seconds. In the case of a focal length of 50 mm: 500/50=10. The maximum exposure time is therefore 10 seconds.

This rule should be kept in mind as a guide. This is a good asset as you want to photograph beautiful fixed stars, but it can of course be overridden to create different photos.

This type of photo, called star trails or star trail, is obtained by multiplying long exposures (between 30 seconds and 1 minute exposure) and by stacking the images in post-production.

Star photo editing

Once your astrophotography session is over, bring your photos to their full potential by running them through photo editing software.

Via Adobe Lightroom, Photoshop, Affinity Photo, Skylum Luminar Neo or DxO Photo Lab, adjust exposure, contrast and, if necessary, use a noise reduction tool to improve your photos. By deepening the blacks, the bright elements are even more brilliant.

Photos of starry skies often turn yellow/ochre tones. Adjusting the white balance is essential to bring in cooler tones, more suited to the sky.

It happens that undesirable elements slip into starry sky photos: a satellite, a plane, etc. which leave a trail that has nothing in common with a shooting star. The defect removal tool in your photo editing software comes in handy for removing them.

Be sure to create your own presets to edit a series of images more quickly. Lightroom presets, for example, are a valuable tool.

Finally, the image stacking method (stacking) is also very useful in astrophotography. This involves combining several images in order to obtain a final photo with refined definition, richer in details, and reduced noise. The higher the number of images to stack, the more stunning the result.

Be careful, however, to ensure flawless stability when shooting to guarantee perfect consistency in your photos. The DeepSkyStacker software, free, allows you to create stacking images easily. Photoshop is an alternative, certainly paying, but just as simple for those used to it, by merging layers.

Some useful applications for astrophotography

Available on Android and iOS, Photopills is a very practical application for planning your astrophoto sessions based on the position of the stars, the Milky Way, etc. The app shows sunrise and sunset times, ideal for knowing what time to start shooting.

Also available on Android and iOS, Star Walk 2 is an interactive real-time sky map to explore space and spot celestial features easily.

If you don't have a camera or are a fan of smartphone photography, no problem: the doors of astrophotography are not closed to you. Although the photo sensors of smartphones are not as efficient as their SLR or hybrid counterparts, they are not, to say the least, capable of obtaining good results. It is also better to turn to a smartphone designed for photography for this exercise, the market being plethora, the photos will be even more convincing.

Some smartphones support RAW format. If so, be sure to change your settings accordingly to take advantage of it.

Equipment for smartphone astrophotography

On the equipment side, equip yourself:

The advantage of smartphone photography is the lightness of the equipment.

The shooting

As for shooting, you can either go through the “ nuit » of your smartphone's camera, suitable for dark environments, either use manual mode, or “pro” mode, to adjust the parameters as you wish. If your phone doesn't have one, you can use third-party applications like NightCap on iOS or ProCam X on Android. Make the following settings:

• stabilize your smartphone on a mobile-friendly tripod or any other suitable support;
• set the aperture to the largest possible value: f/2.8 or less (for the rare smartphones that offer a variable aperture);
• increase the ISO while being careful not to exceed the noise limit of your smartphone;
• set an exposure time between 15 and 30 seconds. It is by carrying out several tests that you will find the ideal long exposure depending on the conditions and your equipment;
• focus on infinity or use your smartphone screen to focus on a star;
• activate the self-timer and shoot

Touch-ups on the smartphone

Finally, move on to editing your star photos on your smartphone. For this, photo editing applications on mobile are of great help. Adobe Lightroom Mobile, VSCO or even Snapseed are excellent tools for adjusting exposure, setting the white balance to a cooler temperature, modifying the framing or reducing digital noise in your star photos.