Introduction to photography of starry sky, orbit and celestial bodies (1)

There is a romantic saying in astrophysics: the starry sky is the hometown of every atom in you. MichaelShainblum, a photographer from America, has a different feeling about the universe and is good at natural starry photography. The night sky and the Milky Way under his lens are gorgeous and wonderful.

Shainblum said, "Sometimes, the starry sky has the biggest surprise and gives you a great view beyond your imagination."

For the northern hemisphere, every September-10, and the starry season of the year, are you eager to move, but you don't know where to start? Starry photography seems to be relatively tall, but in fact, after mastering certain astronomical knowledge and shooting skills, I believe everyone can shoot the most beautiful starry sky. Before sharing, let's enjoy some beautiful pictures of the starry sky.

There are many articles about starry sky shooting on the Internet. I try to combine these fragmented knowledge points with my own experience, sort out the cost series to share, comprehensively explain the pre-shooting technology and post-thinking, and introduce each step of post-processing in detail with examples.

Commonly known as starry sky photography, it can be roughly divided into two categories: deep space photography (celestial photography) and star field photography. Generally speaking, deep space photography refers to photography with the main purpose of shooting deep space objects, which belongs to a professional shooting method, including the moon, the sun, nebulae, star clusters and so on. It can also be divided into two categories: pure deep space celestial bodies and wide-area deep space, which require expensive special professional equipment, such as star guiding equipment, equatorial telescope, frozen CCD, astronomical telescope and so on. Star field photography mainly takes pictures of natural landscape or artificial foreground, and the background is the common starry sky or star orbit.

Astronomical knowledge

Why are other people's photos full of stars flashing, and you are interested in shooting the Milky Way, but the stars in the photos are scattered, and you are disappointed. The fundamental reason is that the Milky Way does not appear in the night sky you photographed. Starry photography is a special subject, which requires not only exquisite early and late technology, but also knowledge of astronomy.

Characteristics and differences of galaxies in the northern and southern hemispheres

The Milky Way refers to the milky white bright belt across the starry sky. The Milky Way intersects the celestial equator in Aquila and is located in the northern hemisphere. The milky way draws a band with different widths on the celestial sphere, which is called the galactic band. Its widest place is 30, and its narrowest place is only 4 ~ 5, with an average of about 20, which is only a part of the Milky Way.

The Milky Way occupies a very important position in China culture. As early as the Han Dynasty, China's famous myth and legend Cowherd and Weaver Girl was included in the literature. China was called Tianhan, Tianhe, Hehan, Han Yin, Xinghe, Xinghan and Han Yun in ancient times.

In fact, you can see the Milky Way at night all year round, but because the silver heart is the brightest and most spectacular part, shooting the Milky Way usually refers to shooting the silver heart in the concept of photography.

Friends who have had the experience of shooting the starry sky know that the direction and time of the appearance of the silver heart in the night sky are different every month and season, and careful planning before shooting is the guarantee of success. In the northern hemisphere, the Milky Way across the sky from northeast to south in the summer night sky is like a rushing torrent. Only the dim cantilever part can be seen in winter, but the opposite is true in the southern hemisphere. Why is there such a big difference between time and orientation? This requires us to understand the relationship between the earth, the solar system and the Milky Way.

Generally speaking, most of the northern hemisphere can be photographed in March-10, most of the southern hemisphere can be photographed in February-10, and only the cantilever part of the Milky Way can be photographed in other months.

Because of the geographical location and the deviation of the earth axis, the shapes and orientations of galaxies seen in the northern and southern hemispheres are different. Starry photography should conform to the laws of nature, and the scene in the photo should appear at a certain moment in nature. What I want to say here is that PS has become a graph that does not conform to the laws of nature, and it is forbidden to joke.

When shooting the Milky Way, the natural conditions in the southern hemisphere are slightly better than those in the northern hemisphere, and the differences can be summarized as follows:

(1) All constellations can be seen at the equator. The farther north you go, the less you can see the southern sky, so the size of Magellanic Cloud in the southern hemisphere is invisible in the northern hemisphere.

(2) April-July is the most suitable season to photograph the Milky Way, when it is spring and summer in the northern hemisphere and autumn and winter in the southern hemisphere.

(3) The shapes of galaxies photographed in the southeast and southwest of the southern hemisphere are reversed, while only one galaxy can be photographed in the northern hemisphere.

(4) The position of the silver heart in the northern hemisphere can usually be well combined with the landscape, but in the southern hemisphere, as the silver heart rises to a certain position, it cannot be combined with the landscape, which is not conducive to composition. Especially after dark from August to June in 5438+00, the silver heart in the southeast is far from the horizon, and it is difficult to combine with the foreground unless there are mountains in the landscape, but the galaxy can be photographed in the southwest, and the shape of the silver heart is reversed.

How to use moonlight to add color to photos

Starry photography is at night, which inevitably involves the moon. Because the brightness of moonlight is very strong, when a bright moon is high in the night sky, many stars are covered by the light of the moon, and few stars are visible. The moon is bright and the stars are few. If you shoot the starry sky in this situation, the moonlight will directly affect the brightness of the Milky Way, and the shooting effect is very unsatisfactory. How to determine the best shooting date and understand the moon phase is a compulsory course for starry sky photography.

There are eight moon phases according to their shapes. The period is one month, and the order is: new moon → waning moon → first quarter moon → convex moon → full moon → convex moon → second quarter moon → waning moon → new moon.

How to avoid too strong moonlight when shooting the Milky Way? First, you can choose to shoot before the moon rises or after the moon sets; Second, during the Emei month, it is also my favorite shooting condition. The moonlight is not very strong and has little influence on the Milky Way. At the same time, it can illuminate the landscape and play a role in supplementing light.

Shooting conditions

weather

Starry photography also needs good meteorological conditions, among which cloud cover and atmospheric transparency are particularly worthy of attention. A moderate amount of thin clouds can set off the atmosphere, which is an important element to add color to the time-lapse photography picture, but the thick clouds all over the sky are a nightmare for starry photography. Therefore, before making a shooting plan, it is generally necessary to understand and predict the local meteorological conditions in the target area.

Ordinary civil weather forecasts often only cover urban areas, and the information content is not targeted enough for starry sky shooting. It is recommended to use "Sunny Bell" website and its related mobile application "Star Guide", which can query the forecast information of cloud cover, transparency, visibility, temperature and humidity in local areas according to geographical location, and is more worthy of reference than civil large-scale weather forecast. In addition, from the experience, strong winds can often bring clear and transparent weather, and the atmospheric transparency is generally high after rain, which is a good time to shoot.

location

Geographical location directly affects the light environment, which is of great significance to starry sky photography. Generally speaking, you should choose a shooting location with less light pollution and high altitude.

The light pollution in the night sky is mainly caused by the light generated by human activities being scattered by dust or water vapor in the low-altitude atmosphere. The easiest way to avoid light pollution is to stay away from the light source as far as possible, which means that starry photographers often look for shooting locations in the suburbs or even in the wild.

Take Beijing as an example. Only about 50 kilometers away from the city center can the Milky Way appear in the sky. Only more than 0/00 kilometers away from the city center/kloc-can we truly appreciate the splendor of the Milky Way.

The increase of human activities makes the pure night sky more and more scarce, so it is very difficult to completely avoid light pollution. We can choose to turn our backs or deviate from the perspective of the city to avoid light pollution. For example, when shooting the summer galaxy in the southern sky, don't choose the location in the north of the city, otherwise the part of the galaxy near the ground will be covered by the light emitted by the city. Or do the opposite, use light pollution to render the atmosphere and make it an integral part of the image. ?

High altitude is another favorable factor for starry sky photography, not to get closer to the starry sky, but to better avoid atmospheric interference; For shooting the starry sky near the city, the altitude of several hundred meters to one kilometer can effectively improve the light environment.

Tipe: The following websites can inquire about the global light pollution situation:

www.lightpollutionmap.info

/maps/world.html

https://blue-marble.de/nightlights

time

First of all, we must determine a large time range, that is, the shooting season of the Milky Way. Secondly, we should inquire about the current rising or falling time of the silver heart, and then judge the best date and time for shooting according to the moon phase.

PlanIt, the APP starry sky prediction software in the mobile phone! For photographers, photography mountains, distant sun, stars, and so on. There are very accurate information about the galaxy and the moon, so you can make careful plans before shooting.

Shooting equipment

Starry photography's pursuit of dim light and complex shooting environment requires adequate preparation on equipment. With the development of technology and manufacturers' targeted design, more and more equipment can be used for starry sky shooting, bringing more colorful means of expression. Knowing and using all kinds of equipment reasonably can make our shooting more effective.

After years of development and polishing, digital SLR/mirrorless cameras has been the main equipment for starry sky photography with perfect functions, excellent comprehensive performance, mature ecosystem and extensive lens selection.

camera

One of the biggest advantages of high-sensitivity full-frame camera compared with APS frame camera is high-sensitivity image quality. Because starry sky photography needs ISO3200-6400 or even ISO 12800, high-sensitivity performance is very important for image quality.

camera lens

In starry sky photography, large aperture lens has obvious advantages, which can not only reduce noise with lower ISO, but also improve the brightness of real scene and the convenience of focusing and composition.

1 Nikon 14-24mm F2.8 and Zeiss 15mm F2.8 are all good shooting lenses in the starry sky. Recently, several wide-angle lenses with large aperture and fixed focus have appeared on the market, such as Sigma/KOOC-0/4 mm f/KOOC-0/.8, Laowa/KOOC-0/2 mm F2.8 and so on. , are the weapon of starry sky photography.

Fisheye lenses with larger viewing angles are also widely used in starry sky photography. These lenses are designed for shooting the sky. The fisheye lens with round frame is suitable for recording all-day pictures, and the fisheye lens with diagonal frame can be used to earn wider scenery. The unique frame and distortion of fisheye lens can create novel and interesting pictures, and it also requires photographers to have strong control over the images. Wide-angle lens is not always used in starry sky photography, and the reasonable use of medium and long-focus lens can often bring unique effects. The focal lens has a large aperture and excellent imaging quality, which can achieve enough exposure to expose the gorgeous colors and rich layering in the central part of the Milky Way.

Of course, these lenses also have some shortcomings, such as high price, poor distortion control, too heavy, etc., which should be considered comprehensively according to their own situation and ability. In addition to the main lens, I also used Sanyo 14mm/F2.8 to shoot the Galaxy, which is a very cost-effective wide-angle lens with large aperture.

Timing cable release

When shooting the Milky Way starry sky, you should also prepare to pay off regularly. Because pressing the shutter by hand in a dark environment can easily cause the camera to shift or shake, the camera will automatically shoot after the timer cable is released and the interval time and the number of shots are set. At present, Canon's 5DS and 5DR, as well as all Nikon's full-frame cameras and some half-frame cameras have interval shooting function. If the camera you use has interval shooting function, forgetting to bring the cable will not affect your shooting of starry sky, galaxy and orbit. Some friends like to use the remote shutter, which is really useful when taking selfies, but I suggest that it is more reliable to bring a wired timed wired release.

High speed memory card

You don't need to take many photos to shoot the starry sky and the Milky Way itself. However, if you want to shoot the circular star orbit or the time delay of the starry galaxy, you need to take a lot of pictures, and finally synthesize the star orbit through the later software or make a time delay photography. Because the pixels of the camera are getting higher and higher now, more high-speed memory cards need to be prepared. It is best to use raw format when shooting, which is convenient for later adjustment.

Tipe: 500 rules of starry sky photography

When shooting the starry sky, in order to ensure that the starry sky is not trailing, we can use the 500 rule of starry sky photography to calculate the appropriate shutter time. Simply put, divide 500 by the focal length (focal length of Quan Huafu) to get the ideal shutter time, for example:

1 1mm:500/ 1 1 = 45s。

16mm: 500/ 16 = 3 1 sec.

24 mm: 500/24 = 2 1 sec

tripod

When shooting the star track, special attention should be paid to the fixing of the tripod, and it is not allowed to touch the tripod when shooting, otherwise the star track will not be successfully spliced later. After setting up the camera and tripod, be sure to carefully check whether each section of the foot tube has been fixed, and the three footholds should be on the flat ground, not on some bumpy edges, so as to avoid sliding during shooting and causing the tripod to shift.

Headlights and flashlights

In order to avoid light pollution, starry sky photography is taken in remote areas far away from the city. Lighting equipment is very important in dark environment, and safety is the first principle at any time. This is an accessory that is often despised. Another function of headlights and flashlights is to fill the foreground and help focus. Wired release, GPS, warm clothes and mosquito repellent are also necessary accessories.

Galaxy shooting skill

Starry photography: What should we shoot? Many people think that photographing the orbit of the Milky Way or stars is a success, and ignoring the landscape is a common problem. At the beginning of this chapter, it has been introduced that star photography is not celestial photography, but a kind of landscape photography, so it is consistent with the concepts of other disciplines in landscape photography. The choice of foreground (landscape) is directly related to the success or failure of photos. Like the sun and clouds, the Milky Way is just the big environment in the photo, and the composition should be coordinated with the landscape. The most common misunderstanding is to blindly pursue the details of the starry sky and ignore the overall composition of the photo.

From the shooting technology, the prophase and anaphase of starry sky photography are more complicated than other subjects. Because light pollution will affect the brightness of the starry sky, we will choose dark areas to shoot, and how to shoot photos with normal exposure in low light environment has become the biggest challenge. Although long exposure can solve the problem of shooting scenery, the position of the stars in the sky is not fixed, but rotates relative to the earth because of the autobiography of the earth. If the exposure time is too long, the star will be "pulled" and the star orbit will be generated. So how to ensure that the stars are not trailing and can be exposed normally? The following is a description of the starry sky and landscape.

Starry shooting parameters

First of all, the parameters should be preset by manual shooting mode m, and the key point is to control the exposure time to ensure that the stars will not become stellar orbits. The rule of 500 can be applied, that is, the exposure time (seconds) is less than or equal to 500 divided by the lens focal length (mm). For example, if the focal length of the shooting lens is 16mm and 500 500 divided by 16 is about 30 seconds, then the shooting time should not exceed 30 seconds. If you want to better control the star to stay in the corner, it is recommended to apply the 400 rule 400/ 16=25 seconds. Note that the above applies to full-frame cameras. If it is an APS camera, the exposure time should be divided by the cropping factor.

In such a dark environment and such a short exposure time, many people take photos that are all black, which involves the combination of the other two parameters. Large aperture and high ISO are the guarantee of shooting a beautiful galaxy. ISO recommends 3200-6400. Isn't such high sensitivity full of noise? This problem will be listed in the noise reduction section below, and now various noise reduction methods can completely solve this problem. The aperture is preferably above F2.8, F4 is the lower limit, and the larger the aperture, the more details of the Milky Way will be photographed.

Four methods of shooting scenery with light source

Without any auxiliary lighting, shooting the landscape with the above parameters will be seriously underexposed, and it will be very dark without details. How to solve this problem?

(1) The best way is to shoot around the moon in Emei at night and use the moon to fill the landscape, so that the natural light source is the most uniform and natural. Theoretically, it is ideal that the surface of the moon does not exceed 1/3, but moonlight will also affect the details of galaxies. The stronger the moonlight, the weaker the details of galaxies.

(2) The actual situation is often limited by objective conditions. It may not be chosen at night when there is a moon in Emei, but sometimes it should be taken before the moon rises or after it sets. At this time, we can use lighting equipment such as headlights or flashlights to artificially fill the foreground. This kind of fill light technology needs repeated practice to achieve natural uniformity, not too stiff.

(3) Another way is to use different time periods (usually blue hours and nights) to shoot the starry sky and the later synthesized landscape. You can shoot the scenery after sunset, the starry sky after the silver heart rises, or you can shoot the starry sky first and shoot the foreground at dawn. The advantage of this method is that the landscape is shot with low ISO, and the image quality is greatly improved, but the premise is to ensure that the camera position does not move during shooting. If you are shooting at the seaside, you should check the tidal fluctuations during the shooting in advance.

(4) In addition to fill the light, you can also expose the landscape for more than a few minutes according to the situation, and then use the mask to synthesize the sky and landscape in Photoshop. However, high ISO long exposure will produce a lot of noise, so it is suggested to turn on the long exposure noise reduction or multiple stacks in the camera to reduce noise in black field shooting and improve image quality. This shooting method is time-consuming whether it is pre-shooting or post-processing.

Manual focusing technique

In the dark environment, the camera can't complete autofocus, so the starry sky photography should be switched to manual focusing mode. Turn on live view, enlarge the image and adjust the focus ring until the stars are clear. When focusing on the foreground, if the display screen can't see the details clearly, you can use headlights to illuminate the foreground to help focus.

It's a lazy trick here, provided that the foreground is not too close to the camera, at least 3 meters away, and it is shot with a super wide-angle lens of16 mm. According to hyperfocal distance's principle, as long as the focus is 5 meters away, the scenery in the picture is very clear. To be on the safe side, I usually focus on 7-8 meters.

Depth of field synthesis

In the weak light environment of large aperture shooting, if the foreground is very close, it is difficult to meet the demand of depth of field for single shooting, and depth of field synthesis technology can be used to solve this problem. Manually focus on the starry sky and the foreground to take two photos, one with a clear starry sky and a blurred foreground. Later, the clear parts of each of the two pictures were combined with masks in Photoshop.

This short summary

1. The galactic season is roughly from March to 10 every year, and April-July is the most suitable month for shooting.

2. Choose cloudless or partially cloudy weather, shoot away from light-polluted areas, and try to avoid moonlight interference.

3. Equipment: high-sensitivity full-frame camera+large aperture wide-angle lens+tripod.

4. Parameters: F4 ISO3200-6400, F2.8, 25-30 seconds.

5. Pay attention to the combination of starry sky and landscape when composing a composition, and choose the appropriate method to make the landscape full of light.

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