What should I do if more than 85% of the points calculated in f2 are not at the same time?

Basic Digital Photography Preface More and more friends are starting to use digital cameras because they are convenient and can share the results of shooting with friends in real time. From what I have observed this year, digital cameras are definitely on the way to replacing ordinary point-and-shoot cameras. From the falling prices of many entry-level to mid-range cameras, the improvement of quality, and the cooperation of interface equipment such as lightweight printers, I believe that it will not be surprising. In a few years, digital cameras can eliminate more than 90% of traditional point-and-shoot cameras and become a must-have product for home use. Digital cameras have the characteristics of convenient and real-time viewing, bringing unprecedented convenience to traditional photography. But on the contrary, many friends have pointed out that it is easy to take a clear and beautiful photo with a traditional digital camera, but why do digital cameras often appear "pine, gloomy, and foggy"? This involves the essential difference between digital and traditional film cameras. Although both are tools for shooting images, due to this difference, their operations are different. The author takes this opportunity to discuss with you some experience in operating digital cameras, and also compares the similarities and differences with operating traditional film cameras. I hope it can help you to use your equipment more smoothly. The discussions covered in this article generally include: characteristics of digital cameras, aperture shutter, focus, metering, white balance, depth of field, night photography and flash, issues such as hand shake and tripod, exposure issues, photo storage, etc. ..You are also welcome to raise questions and we will discuss them together. Characteristics of digital cameras (a) Digital cameras, as we can see, are a "digital" "cameras". Putting aside the "digital" part, it is still a camera to the fullest. What is the definition of camera? To put it most simply, it is a tool that captures and leaves images. When you see some people, things and scenes and want to keep them for later review, the camera will do this for you. Of course, what a still camera leaves behind is just a fleeting image. It freezes this moment in the world for you and allows you to keep this moment forever. If you want to leave a dynamic story, only a camcorder can help you. Of course, today's advanced still digital cameras can also leave a dynamic record, but this is an additional function of digital cameras and is not the scope of traditional cameras. (b) From the perspective of capturing images, digital and traditional cameras are basically the same. The camera body is matched with the lens. We use the aperture-shutter combination to control the amount and speed of light entering the lens. The light passes through the lens and then enters the photosensitive component, where it is condensed into an image. Up to this point, there is still no distinction between digital and traditional, because this is still the optical part. (c) Condensed image, in the case of traditional cameras, it is the photosensitive film, in the case of digital photography, it is the photosensitive CCD/CMOS. In fact, they are all just different in media. In traditional cameras, we have to insert film, let it be exposed to light, and then develop it into a complete photo. With digital cameras, we don't need to insert film because the "film" (CCD/CMOS) is already built-in, which is different. What is important is that the CCD/CMOS will generate raw data after being exposed to light. The image processor in the digital camera will use this data and cooperate with the camera's operating system to generate an image and store it in the memory to become an image. file, this is the finished photo from your digital camera. (d) Therefore, in essence, there is no difference between traditional cameras and digital cameras; however, due to different image processing processes and some innate technical differences, there will be many operational differences. The following are some examples (only listed as they will be discussed in detail below): i. The built-in settings of the digital camera, such as white balance, contrast, sharpness, saturation, etc. ii. Focal length and depth of field iii. The range of the aperture iv. The range of the photo Resolution and pixels v. Focus, zoom and other issues Aperture shutter (a) The application of aperture shutter is basically a prerequisite for photography. Although there are many portable cameras on the market, or they are called fully automatic, they basically determine the aperture and shutter settings for you in different surroundings. All you have to do is point and shoot. Most digital cameras of relatively high quality provide various manual settings, such as aperture priority, shutter priority, full manual, plus the original automatic and program automatic modes. Basically, there are very sufficient conditions. Let's learn photography. (b) What is aperture? As mentioned in the previous section, controlling the amount and speed of light depends entirely on the cooperation of the aperture and shutter. The aperture can be regarded as the pupil of the eye. The aperture value is the size of the pupil opening and closing. The aperture is usually expressed by the f value. Please remember that the larger the number, the finer the aperture. Each time the aperture increases by one step, the amount of light entering will decrease. Reduce by half. The orthodox aperture levels are as follows: f1, f2, f4, f8, f11, f16, f22, f32, f64, f128. That is, is one aperture finer than , but one aperture larger than , and so on. The , , etc. we sometimes see are actually the same principle. For example, located in the middle of and , it can be said to be half a step finer (the amount of light entering is reduced by a quarter), but half a step larger.

The aperture value range of ordinary civilian digital cameras is not as wide as that of traditional cameras. Since the CCD/CMOS area of ??digital cameras is much smaller than that of 135 film (not counting digital single-lens cameras), the "pupil" of the lens is also much smaller, which changes the When used in digital cameras, it is not difficult to create a large aperture, but it will be extremely fine to create a fine aperture above f16 and f22, so most digital cameras are only about f11 or so. (c) What is shutter? Shutter speed is the time it takes for light to enter the lens and make the film sensitive. In other words, the time it takes for the shutter to open and close is the time it takes for your eyes to open. The shutter speed is measured in seconds. It goes without saying that the faster the shutter, the shorter the exposure time. The shutter steps are as follows: 1/16000 second, 1/8000 second, 1/4000 second, 1/2000 second, 1/1000 second, 1 /250 sec, 1/125 sec, 1/60 sec, 1/30 sec, 1/15 sec, 1/8 sec, 1/4 sec, 1/2 sec, 1 sec, 2 sec, 4 sec, 8 sec wait. Likewise, 1/4000 second is one shutter step faster than 1/2000 second, and so on. For ordinary civilian cameras, the shutter range is 1/2000 to 15 seconds at most, which is also a more commonly used range. Most of the shutter speeds beyond this range can only be seen in more professional cameras. There is another item called B (bulb) The shutter allows you to decide the length of the shutter, starting from when you press the shutter until you release it. Some models of general digital cameras also provide the option of B shutter, but there is still an upper limit on the time; and single-lens reflex cameras ( Whether digital or not) will provide unlimited B shutter selection. (d) To get the correct exposure, you need a good combination of aperture and shutter speed. Since the aperture size is directly proportional to the amount of light entering the lens, and the shutter speed is inversely proportional to the time the light acts on the light, for a certain light intensity, to obtain the same sensitivity, when the aperture is larger, The shutter speed should be smaller, and a slower shutter speed should be selected when the aperture is small. As for the best combination, it depends on what kind of effect you want. (e) Generally speaking, the larger the aperture, the shallower the depth of field\. For example, if you want to take a portrait, you often want the portrait to be clear and the background to be hazy. This kind of "clear portrait but hazy background" is the so-called shallow depth of field. At this time, you need to widen the aperture (coupled with a long zoom, the effect will be better). And if you want to photograph a landscape and you want everything to be clear, you have to narrow the aperture to achieve a wide depth of field. Since the aperture and shutter value range of general digital cameras is not wide enough, there are sometimes creative limitations. For example, if you open the aperture as wide as possible in daylight, but the shutter speed is not fast enough to match it, the light will be overexposed. At this time, you have to make a choice, give up the depth of field that is too shallow, or use the help of a filter. (f) In terms of shutter application, general examples include sports, fireworks, flowing water, waterfalls, etc. A fast shutter can freeze a moment's action, such as an athlete jumping up and stopping in mid-air; a slow shutter can produce a dynamic performance, such as making a waterfall appear soft on a piece of cloth. I usually use a slow shutter speed for night scenes because I want to have bright and dazzling lights (with a narrow aperture to avoid excessive light). Shadow water droplets use a fast shutter speed because you want the water droplets to solidify and float above the water surface. In short, different shutter values ??will produce different effects, and it all depends on your creative inspiration. (g) Various touch modes - Generally, mid- to upper-level digital cameras have several aperture touch modes: i. Aperture priority touch mode - you decide the aperture value yourself, and the camera will use its metering system to measure it based on your focus. light, and then gives you a shutter value. ii. Shutter priority mode - you decide the shutter value yourself), the camera will use its metering system to measure the light based on your focus, and then give you an aperture value. iii. Fully manual - you have full control over the aperture and shutter value. However, many cameras will still meter the light based on your focus and provide a display to let you know whether there is under/over and how many levels, etc., so that you can adjust an appropriate light combination. iv. Programmed mode - referred to as P Mode. In this mode, the camera will use its metering system to meter the light based on your focus, and then give you an aperture-shutter combination. But you can also choose to change another aperture-shutter combination and still have an appropriate light value (assuming the metering is correct). For example, if the metering application is f/, 1/60 seconds, you can choose to change it to f/4, 1/125 or f/8, 1/30. These three groups of aperture-shutter combinations all produce the same light value. So some people say that this is a slightly clever fool mode. v. EV - Light compensation. Allows you to add or subtract the light value to the light value measured by the camera. Usually, because there are other external factors that affect the camera's metering, you can increase or decrease the light based on your own experience or the scene environment. Usually in the aperture priority mode, increasing the EV value by one level is equivalent to slowing down the shutter by one level; similarly in the shutter priority mode, increasing the EV value by one level is equivalent to increasing the aperture by one level. There is no option to add or subtract EV in the fully manual mode because you have full control over the aperture-shutter combination. Focus (a) Focus is to bring the people and scenic spots you want to photograph into focus. The focus must be correct so that the subject can appear clearly in the lens.

Imagine that the lens is a pair of human eyes. You must focus on a certain thing or person before it appears clearly in front of your eyes. Everything else that is not in focus will be hazy. Basically, in a photo taken by an autofocus camera, excluding the factor of hand shake, no matter how shallow the depth of field is, there must be a focus point, that is, at least one point must be clear. If you find that there is no focus point in the entire photo, When the focus point appears, it may be due to one of the following factors: i. Hand shake ii. Pressing the shutter before completing the focusing process iii. The focal length is too close, exceeding the camera’s closest focus range iv. The camera cannot find the focus (for example, video Sky** It is very easy to lose focus on the sky, especially when the sky is not bright, because it involves metering issues, so we will discuss it in the next part)) (b) Basically, the autofocus of modern digital cameras is very accurate. , and some also provide manual focus function. However, a deeper understanding of the camera's focusing performance can greatly increase your understanding of the camera. The following are commonly used focusing options for reference: i. Focusing method: The focusing method of almost all autofocus cameras is to press the shutter button halfway to lock the focus, and then press it fully to shoot. Some of the smarter cameras will prevent you from pressing all the way down to ensure that there is a focus point when you can't find a focus point. ii. Single AF vs Continuous AF: Single AF is a single focus, the camera will not automatically focus until you press the shutter button halfway. Press the shutter button halfway and don't let go. You can clearly see the focus situation on the LCD display. If you are taking some photos with a short depth of field (especially macro), you can see the subject more clearly against the hazy background. When you are sure that your focus is complete and correct, you can continue to press all the way to shoot. Continuous AF is continuous focus. , the camera will constantly activate the focus system to focus on what it thinks is the most correct object. Continuous has the advantage of further speeding up focusing because it operates non-stop and is helpful in making up for the focus of moving objects. But you still have to press halfway to lock the focus before you can press fully to shoot. The disadvantage of Continuous is that it consumes a lot of power and is easy to lose focus. Especially when digital cameras have relatively slow focusing speed and high power consumption, these two disadvantages are more obvious. Therefore, it is recommended that single AF should be used under normal circumstances. iii. Multi-point focus: In the past, with cameras, most photographers used the center as the focus to compose their shots. In addition to being a test of orthodox and stable photography skills, the main reason why old automatic cameras can only use the center point to focus is one of the main reasons. At that time, smart photographers would change the focus by half-pressing and moving. The so-called half-pressing and moving meant first aligning and locking the focus with the middle point (half-pressing still), then moving the camera to recompose the shot, and then fully Press Capture. In this way, the locked focus will not change, but it does not have to be placed in a rigid central position. The invention of multi-point focusing improved the above situation. Just think about it. Although the half-press movement method can also achieve the effect of "artificial multi-point focusing", discerning photographers will find that it is actually easy to lose focus because it is difficult to ensure that our camera is in focus when we move it. Maintaining an absolute line of balance with the object in focus. That is to say, our camera may move closer or further away from the object being focused. In the case of shallow depth of field, it is easy to get out of focus. With the emergence of multi-point focusing, we no longer need to move the camera. We can select the focus point directly on the camera, completely avoiding the aftermath of moving the camera. As for the number of focus points, different cameras have different specifications, usually ranging from 3 to 9 points. New cameras (such as the new DC of the Canon Digic system, . G3, S45) have the function of selecting any point arbitrarily. , indeed very convenient. iv. Manual focus: Manual focus basically does not have the above problems, because it is completely up to you to control the focus.