The skill of photography.

The quality of the photo is related to the exposure, that is, how much light is needed to make the ccd get a clear image. Exposure is related to light passing time (determined by shutter speed) and light passing area (determined by aperture size).

Then, in order to get the right exposure, we need the right combination of shutter and aperture. When the shutter is fast, the aperture will be larger; The aperture is smaller when the shutter is slow.

Shutter priority refers to the exposure value calculated by the automatic metering system of the machine, and then automatically determines how much aperture to use according to the shutter speed you choose.

Aperture priority refers to the exposure value calculated by the automatic metering system of the machine, and then automatically decides how many shutters to use according to the aperture size you choose.

Manual mode means that you specify the aperture size and shutter speed yourself.

The larger the aperture, the more light passes through per unit time, and vice versa. Aperture is generally expressed as the letter "F+ value", such as F5.6, F4, etc. It should be noted that the smaller the value, the larger the aperture. For example, F4 is larger than the aperture of F5.6, and the difference between two adjacent apertures is twice, which means F4 is twice as big as that passing through F5.6. Relatively speaking, the definition of shutter is very simple, that is, the time allowed for light to pass through the aperture is expressed by numerical values, such as 1/30 seconds, 1/60 seconds, etc. Similarly, the difference between two adjacent shutters is twice.

The combination of aperture and shutter forms exposure, which is not unique under certain exposure conditions. For example, the current normal exposure combination is F5.6 and 1/30 seconds. If the aperture is increased by one step, that is F4, the shutter value at this time will become 1/60, and this combination can also achieve normal exposure. Although different combinations can achieve the same exposure, the pictures taken have different effects.

The concept of "depth of field" is involved here. The so-called depth of field means that when the lens focuses on the subject, the subject and its scenery before and after have a clear range, which is called depth of field.

After understanding the basic concepts of aperture, shutter and depth of field, it is not difficult to use aperture limit or shutter first.

Aperture priority is to manually define the size of the aperture, and then use the camera's metering to obtain the corresponding shutter value. Because the aperture directly affects the depth of field, this mode is most widely used in ordinary shooting. When shooting portraits, we usually use large aperture and long focal length to blur the background and get a shallow depth of field, which can highlight the subject. At the same time, a larger aperture can also obtain a faster shutter value, thus improving the stability of hand-held shooting. When taking photos such as scenery, we often use a smaller aperture value, so that the range of depth of field is wider, which can make the distant and nearby scenery clear, which is also applicable when shooting night scenes.

Contrary to aperture priority, shutter priority is to obtain aperture value through camera metering when the shutter is defined manually. Shutter priority is mostly used to shoot moving objects, especially sports shooting. Many friends find that when shooting moving objects, the subject is often blurred, mostly because the shutter speed is not fast enough. In this case, you can use the shutter priority mode, roughly determine a shutter value, and then shoot. And the motion of the object is generally regular, then the shutter value can also be roughly estimated. For example, the shutter speed for photographing pedestrians is only1125 seconds, while it takes11000 seconds for photographing falling water droplets.

In the case of aperture priority, we can easily control the depth of field by changing the aperture size, while in the case of shutter priority, using different apertures can achieve good shooting results for moving objects. Both should be used flexibly to meet our shooting needs in different situations.

Secret of practical operation skills of DC flash lamp

Macro shooting needs dimming.

Nowadays, digital cameras generally have built-in flash, so pay attention to the distance between the camera and the subject when using the built-in flash. Too close will lead to overexposure, too far will make the light distribution uneven, leading to underexposure. Users had better consult the user manual of digital camera to know the use range of built-in flash, which can generally achieve good results. Using digital camera for macro shooting, because it is very close to the subject, using the built-in flash will only lead to overexposure, so it is necessary to reduce the light.

Dimming is to reduce the output intensity of the flash. You can adjust it in a digital camera, but it's not enough. The light is still strong. You can cover the flash with your hands and pay attention to your fingers, which can reduce the light intensity to some extent. In practical use, it is found that simply using soft paper such as napkins can also have a good effect and make the light soft.

Change the angle of the flash

When shooting with a flash, many people habitually make the flash parallel to the subject to make the light uniform. However, when shooting reflective objects, such as glass and various computer cards, it will produce bright spots on the objects and destroy the harmony of the picture. At this time, it is necessary to appropriately change the shooting angle of the digital camera and shoot from the side to avoid bright spots.

When the contrast between the subject and the background is large, fill the light appropriately.

Don't think that you only need to use a flash when the light is dark. Sometimes you must use a flash to fill the light when the light is sufficient. When shooting against the light, there is a great contrast between the subject and the background. If the subject is exposed, the background will inevitably be overexposed, the background will return to normal, and the subject will be underexposed. At this time, you need to fill the light with a flash.

Filling the light is not only to turn on the flash directly, but also to master certain skills. You can set the camera to aperture priority mode, set the aperture value, measure the background with spot metering, and record the measured shutter value. Then switch to manual mode and set it to the measured aperture and shutter value, and then set the flash to forced flash to shoot. In this way, both the subject and the background can be taken into account, the background of the photo returns to normal, and the subject can be well represented.

Slow flash

Generally speaking, it is not advisable to use flash when shooting night scenes. A small aperture and a long exposure can show a beautiful night scene. Flash is generally used to shoot portraits at night. If you directly turn on the flash to take a portrait, the restoration of the character is normal, but the night scene behind it is very dark and cannot be restored. At this time, you need to use the slow flash function. Slow flash will take a long shutter time, illuminate the subject with a flash, and cooperate with the slow shutter to ensure that the background can also be displayed. If your camera already has a slow flash function, just use it directly. Otherwise, you can set a longer exposure time in manual mode and achieve the same effect.

Use of flash lamp

An external flash, that is, an external flash, has a built-in flash. Why do you need an external flash? The main reason is that the built-in flash has low power and small shooting range, while the external flash has high power and wider natural shooting range. The built-in flash has been fixed, and the direction cannot be adjusted, while the external flash can be flexibly adjusted up, down, left and right, making it more convenient to use. However, not all digital cameras can be equipped with flash, and digital cameras need hot start or synchronous interface to use flash.

Flashover index is an important parameter of flashover, which determines the flashover power. Generally speaking, flashover with GN value between 20 and 30 can meet our basic requirements. I suggest you choose the original flash, which can achieve good results, and these flashes have automatic function, which is very convenient to use. If you choose manual flash, you need to set an appropriate aperture value when shooting. GN=F (aperture) ×L (distance), you need to set the aperture size according to the distance between the camera and the subject. For example, if the flash index of the flash is 24 and you are 3 meters away from the subject, then your aperture should be set to F8. Because the flash time of the flash is very short, the shutter setting is not very important at this time, just set it as a safety shutter (that is, the reciprocal of the focal length of the lens at this time).

When shooting with flash, the flash is usually aimed at the subject, which is easy to cause shadows. Using flash to jump can solve this problem well. Jumping flash is a very common way to use flash, that is, the flash is not directly facing the subject, but has a certain angle. Using walls and ceilings to reflect light can make the light naturally soft.

There are many application skills of flash. Due to the limitation of space, it is impossible to cover everything. Only some of the most common usage methods can be listed, and many application skills need to be discovered by yourself.

Strange! Why DC macro depth of field is particularly good?

It is an indisputable fact that the shallow depth of field of DC is not as good as FC. However, the macro time shallow depth of field effect of DC is quite good. The picture below is a macro photo taken with a D7 camera. You can see that the depth of field in the photo is very shallow. Why does the shallow depth of field effect of DC match FC in macro photography?

In general, we compare photos with the same visual impression. As shown in the figure below, it is reasonable to compare the same scene shot by three different cameras. Obviously, in this contrast, the angle of view when shooting remains the same. That is to say, we often say that the equivalent focal length of 35mm cameras is the same, but the actual focal length is different.

How to use different ISO values?

ISO means the speed of film exposure in traditional cameras. Usually we can clearly see the ISO value on the used film packaging, such as ISO 100, ISO 200, ISO 400 and so on. , extended to digital cameras, equivalent to CCD photosensitive speed. By adjusting the ISO value, the photosensitive sensitivity of CCD can be changed. The higher the ISO, the faster the photosensitive speed of CCD. In other words, under certain exposure conditions, the higher the ISO, the shorter the exposure time.

The relative relationship between ISO sensitivities of different films is the same as that between camera shutter index or aperture index, that is, the speed of ISO 100 film is twice that of ISO 50 film, that is, the sensitivity of the former is twice that of the latter. That is to say, if you shoot a scene with ISO 200 film at 1/250 seconds and aperture f 8, then shooting the same scene with ISO 100 film must give twice the exposure. Why? Because the sensitivity of ISO 100 film is only half that of ISO 200 film.

The improvement of ISO can effectively reduce the exposure time of CCD, which provides convenience for us to shoot in low light. Because it usually takes a long exposure time when shooting in low light or at night, improper use of flash is easy to destroy the exposure, and hand-held shooting has to use a tripod to fix the camera to take clear photos, especially for users of small digital cameras. How is it possible to carry a tripod for entertainment?

Using different ISO to achieve almost the same shooting effect, but the shutter time is greatly accelerated. The faster the shutter speed, the better it is to capture moving scenes, including animals, competitive games, water droplets and so on. Even static water droplets can be photographed, which are based on higher ISO.

But is the higher the ISO, the better? Many friends may think so. Isn't the film bought in the market more expensive and more sensitive? It is true that high ISO can be used in situations that require long exposure, so what about the image quality under different ISO settings?

The higher the ISO, the more obvious the graininess of photos. For film, graininess is caused by the chemical changes of silver halide during rapid exposure, while for digital cameras, noise is caused by uneven pixel exposure caused by CCD rapid exposure. In this way, a higher ISO setting is not suitable for pictures with higher quality requirements, especially portrait photography, still life shooting, close-up and so on.

Therefore, when setting ISO, we should use it flexibly, which is also a big advantage of digital cameras. Free play, even a small entertainment digital camera, I believe it can bring its performance to the extreme and take excellent photos!