How to operate when observing a solar eclipse

Visual observation means direct observation with the naked eye or observation with the naked eye through instruments. First of all, let me state that the sun cannot be observed directly with the naked eye. Because the sunlight is so strong that you cannot observe, and may even burn your eyes, you must have a light reduction device when observing, otherwise you will not be able to observe! Here are several visual observation methods: Wear a pair of sunglasses that are dark enough. (Such as welding sunglasses) Find a piece of glass and blacken it on a kerosene lamp. When a solar eclipse occurs, it can be observed through this blackened glass. Use one or several scrap photographic films and overlap them. When a solar eclipse occurs, you can look at the sun through these films. This method can increase or decrease the number of film layers at any time according to the intensity of the sunlight. It can also be installed in a homemade On the glasses frame, it is very convenient to use. Take a basin of water and pour an appropriate amount of ink into it. Let it sit for a while and then look at the reflection of the sun through it. This is a simple and easy observation method. Use a small telescope to see the projected image of the sun. The projection plate is installed at one end of the eyepiece. Adjust the focus of the eyepiece so that a clear image of the sun appears on the projection plate. When a solar eclipse occurs, you can observe the entire process of the solar eclipse on the projection plate. During a total solar eclipse, the sun's body is completely covered, leaving only the upper atmosphere of the sun - the corona. At this time, the light is soft and the scenery is pleasant. You can safely and boldly look at it with the naked eye. However, during a partial eclipse, the sun's rays are still relatively strong. Yes, in order to protect your eyes, you need to use light reduction equipment to observe, and you cannot observe it directly with the naked eye. Fans must be very careful about this. 2. Photographic Observation Methods The two methods of photographic observation of solar eclipses we introduce here are: one is to use an astronomical telescope equipped with a 135 single-lens reflex camera body to capture the focus image of the sun; the other is to use a camera to directly capture the solar eclipse. Taking photos and observing with a telescope. Taking a focal image is actually to use the objective lens of the telescope as the lens of the camera. In this way, the effective aperture and focal length of the camera will be increased accordingly, which is very beneficial to astronomical photography. ①The 120 mm catadioptric telescope is an equatorial device with a rotating clock for tracking and observation. It comes with an interface for a 135 single-lens reflex camera (Haio DF). It is very convenient for photographic observations. It is very convenient for photographic observations of the solar eclipse. The specific requirements are as follows: A light reduction device is required for observing the sun. The 120mm telescope is originally equipped with a 1/2000 light reduction plate, which must be used during observation. When taking pictures of the corona during a total solar eclipse, you don’t need to bring a light-reducing plate because the corona’s light is weak and you can take pictures directly. The telescope must be adjusted before the observation. Before the observation, the telescope's mechanical system, optical system, and tracking system must be comprehensively inspected and debugged to ensure that it operates normally during observation. After the instrument is adjusted, a trial shot and debugging must be carried out on site before the observation. First, you need to level the mirror (use the horizontal bubble at the base), and then adjust the polar axis of the telescope. In advance, you need to find out the geographical latitude of the observation site, that is, what is the height of the horizon of Polaris (the polar axis is aligned with the North Pole for easy tracking) ). If it is inconvenient to use the sun to set the north-south line to adjust the polar axis during the day, you can adjust it to the North Star at night in advance and fix the instrument at the observation location. If conditions do not permit, you can also use Polaris to mark the north-south line at the observation location at night. Before observing during the day, you can use the north-south line marks set at night to orient the polar axis. This method is also advisable. Adjust the focal length of the telescope Correctly Adjusting the focal length of the telescope is a very important link if you want to obtain good observation results. The focal length of the 120mm telescope for photographic observation is adjusted by rotating the focusing wheel of the telescope and directly viewing the image in the viewfinder of the camera. One problem that needs attention is that the viewfinder of some cameras (such as Hiou DF cameras) has a piece of frosted glass (i.e. frosted glass), so it is difficult to see the reality of the image, so it needs to be adjusted multiple times. The following methods can be used : See the virtual reality at the edge of the sun when adjusting the focus? Furthermore, if there are large sunspots on the sun at that time, you can also focus on the sunspots. In this way, you can rotate the focus wheel back and forth many times to monitor the changes in the virtual and real sun image through the viewfinder, and just choose the best position. In short, with repeated practice and multiple test shots, it is not difficult to adjust the focus. During the shooting process, be sure to have a shutter release cable and do not press the shutter with your hands. To prevent the vibration of the instrument and camera from causing unclear imaging, it is best to monitor the viewfinder with your eyes when pressing the shutter to prevent the sun image from being always within the field of view or deviating from the field of view due to accidental bumping of the telescope and inaccurate tracking. occur. The whole process of observing the solar eclipse must be planned in advance. The Hi-O DF camera used for photographic observation must have a film size of 135 and a maximum of 36 shots. This requires a detailed plan before the observation, because the entire solar eclipse process takes about more than two hours. So we need to plan and arrange the 36 negatives. Observing the very phase of a solar eclipse (corona) is important. It is best to use no less than 10 films to take corona images. When shooting, don't just use the same exposure time, but use several different exposure times. In this way, the certainty is greater and good observation results can be obtained. ②The shooting method of the 150mm telescope (made in Japan) is basically the same as that of the 120mm telescope. The difference is that the base of the 150mm telescope is a tripod. Therefore, you should pay attention to the following aspects when observing: Use the tripod as far as possible before observing. The ground may be spread out to maintain stability, and the tripod must be leveled. The balance of the telescope should be adjusted properly. It is best to make adjustments after installing the camera. If the balance deviation is too large, it will affect normal tracking. The light reduction device can be the one originally produced by Nanjing Astronomical Instrument Factory, or other types of light reduction devices, but the effect will be determined after many test shots.

Be particularly careful when observing and keep your hands and feet away from the tripod and mirror. Otherwise, if the mirror shifts, the shooting may fail. ③ When using a horizontal or equatorial 80mm refractor telescope to take photos and observe a solar eclipse, the method is similar to the one mentioned above. However, this type of telescope does not have an automatic tracking device, so when shooting, someone needs to always monitor the viewfinder and constantly adjust the two micro-motion spirals so that the sun image is always within the field of view. Using a camera to take photos of a solar eclipse directly. There are quite a few astronomy enthusiasts who may not have small astronomical telescopes in their hands, but it is very common for people to have cameras in their hands. It can be said that using a camera to take photos of a solar eclipse directly can still get good observation results. The following introduces the observation methods and places to pay attention to. ⑴ Since the sun image on the film is much smaller and the resolution is much lower than taking pictures with a telescope, it is best to use a 135 single-lens reflex camera, ideally equipped with a telephoto lens of more than 200 mm. ⑵ It must be equipped with a more stable tripod and must be equipped with a shutter release cable to avoid pressing the shutter by hand. ⑶ The exposure time is not easy to be too long, because if the exposure time is too long without a tracking device, the sun image will be elongated, which will affect the observation results. ⑷ During the partial eclipse, the sunlight is still very strong, so appropriate filters must be added. When taking pictures of the total eclipse, you must remove the filter and take pictures directly. ⑸Use a 120mm camera to shoot the entire solar eclipse on the same film. That is, a series of sun images of different shapes are obtained on the same negative film. to see the entire process of the solar eclipse. You must use a camera with a shutter release capable of multiple exposures on the same film. When shooting, place the camera on a tripod and add appropriate filters when there is a partial eclipse. According to the actual situation, see how long it takes from initial loss to full circle, and how many images of the sun can be taken on one film. It is best to place the total eclipse image in the middle, and the front and rear should be even and symmetrical. It would be better to take additional shots of the scenery after taking pictures of the total eclipse. But it takes many test shots beforehand to achieve success. 3. Suggested observation items: Observing partial eclipse: Be sure to add appropriate filters when observing and taking photos. Observing Bailey's beads and solar prominences: The key to taking good photos of Bailey's beads and solar prominences is to grasp the timing, because they are fleeting and can last only a few seconds at most. Therefore, it is necessary to take photos one or two before the eclipse and before the light is generated. Begin to monitor the ground glass on the viewfinder closely after 10 minutes. As soon as you see Bailey's beads and solar prominences, expose decisively without hesitation for a moment. Be careful not to forget to remove the filter. Observing the corona (inner and outer corona) Observing the corona is a key item in the entire solar eclipse process. Therefore, you must master the observation method. First, don’t forget to remove the filter. When observing the inner corona, the focal length of the telescope can be longer (focal length 1000 mm) ~1500 mm is enough). When observing the corona in a large area, the focal length of the telescope should be shorter (focal length is between 500~1000 mm). Celestial objects are imaged at the focal plane of the telescope. The size of the image depends on the focal length of the objective lens. It can be expressed by the following formula: In the formula, d——the size of the image on the film; F——the focal length of the objective lens, expressed in millimeters; θ——the angular diameter of the celestial body, such as the sun, which is about 30ˊ. According to this formula, you can calculate the size of the sun's image on the film when observing with the telescope or camera you use, and determine your main observation items. If you want to make a successful observation, in addition to paying attention to the methods mentioned above, it is also crucial to master the exposure time.

(See solar eclipse photography exposure time reference table)