What do AUTO and p in digital cameras stand for respectively? 1! What's the difference

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More and more friends start to use digital cameras, because digital cameras are convenient and can share the shooting results with friends in real time. From my observation this year, digital cameras definitely have the trend of replacing ordinary dumb cameras. From many computers to intermediate computers, the price has dropped, the quality has improved, and with the cooperation of interface devices such as portable printers, it is believed that in a few years, digital cameras will be able to eliminate more than 90% of traditional dumb cameras and become a necessity for household products.

Digital camera has the characteristics of convenient and real-time inspection, which brings unprecedented convenience to traditional photography. But on the contrary, many friends have suggested that it is easy to take clear and beautiful photos with traditional melon cameras, but why do digital cameras often appear "loose, gray and fuzzy"? This involves the essential difference between digital and traditional film cameras. Although both of them are tools for shooting images, they are different in operation because of this difference.

Take this opportunity to discuss some experiences of digital camera operation with you, and compare the similarities and differences with traditional film camera operation, hoping to help you use your own equipment more conveniently. The discussion involved in this paper generally includes:

The characteristics of digital cameras, aperture shutter, focusing, photometry, white balance, depth of field, night shooting and flash, hand shake, tripod and other issues, sun exposure, photo storage, etc ... You are also welcome to ask questions and discuss together.

Characteristics of digital cameras

As we can see, a digital camera is a kind of "digital" camera. Aside from the "digital" part, it is still a camera. What is the definition of a camera? Simply put, it is a tool for taking and taking pictures. You see some scenes of people and things, and you want to save them for the future, then the camera will do it for you. Of course, the still life camera only leaves images, which solidify this moment in the world for you and make you leave this moment forever. If you want to leave a dynamic story, only the camera can help you. Of course, today's advanced static digital cameras can also leave new dynamic records, but this is an additional function of digital cameras, not the category of traditional cameras.

(b) From the perspective of shooting images, digital cameras are basically the same as traditional cameras. The camera body cooperates with the lens, and we use the combination of aperture and shutter to control the amount and speed of light entering the lens. After passing through the lens, the light enters the photosensitive element and converges into an image. At this point, there is still no distinction between digital and traditional, because it is still an optical part.

(c) The condensed image is the sensitivity of film in the traditional camera stage and CCD/CMOS in the digital photography stage. Actually, it's just media differences. In traditional cameras, we put the film in, let it be exposed, and then develop it into finished photos; We don't need to put the film in the digital camera, because CCD/CMOS is built in. The difference is that CCD/CMOS will produce original data after exposure, and the image processor in digital camera will cooperate with the camera's operating system to generate images based on these data and store them in memory as image files, which is the finished photos of digital camera.

(d) Therefore, there is no essential difference between traditional cameras and digital cameras; However, due to the different image processing processes and some innate technical differences, there will be many operational differences. The following are some examples (only these examples are listed because they will be detailed below):

First, the built-in settings of digital camera, such as white balance, contrast, sharpness, saturation, etc.

Two. Focal length and depth of field

Three. aperture

Four. Resolution and pixels of photos

Verb (abbreviation for verb) focus, zoom and other problems

diaphragm shutter

(1) The application of aperture shutter is basically a prerequisite for photography. Although there are many instant cameras or fully automatic cameras on the market, the aperture shutter settings are basically determined for you in all different environments. All you have to do is aim and shoot. Most digital cameras with relatively few stages provide various manual settings, such as aperture priority, shutter priority, full manual, and the original automatic and programmed automatic touch mode, which is basically enough for us to learn photography.

(b) What is an aperture? As mentioned above, controlling the light quantity depends entirely on the cooperation of the aperture shutter. Aperture can be regarded as the pupil of the eye, and the aperture value is the opening and closing size of the pupil. Aperture is usually expressed by f value. Remember, the bigger the number, the thinner the aperture, and the amount of light entering will be reduced by half with each step of aperture increase. The orthodox aperture levels are as follows: f 1.0, f 1. , f2, f2.8, f4, f5.6, f8, f 1 1, f 16, f22, f32, f64 and f 16. That is to say, f 1.4 is one aperture thinner than f 1.0, but one aperture larger than f2.0, and so on. We sometimes see things like f 1.8 and f7. 1, but the principle is the same. For example, f 1.8 is located between f 1.4 and f2.0, which can be said to be half the level of fine f 1.4 (the light input is reduced by a quarter), but it is half a level larger than F2.0. The aperture range of general civil digital cameras is not as wide as that of traditional cameras. Because the CCD/CMOS area of a digital camera is much thinner than that of 135 film (excluding digital SLR cameras) and the "pupil" of the lens is also much thinner, it is not difficult to make a large aperture of f 1.8 and f2.0 on a digital camera, but it is necessary to make a small aperture to F66.

(c) What is a shutter? Shutter speed is the time for light to enter the lens and make the negative film sensitive. In other words, the time when the shutter opens and closes is the time when you belittle your eyes. The shutter is in seconds, which is logical. The faster the shutter, the shorter the flash time. The order of the shutters is as follows:116000 seconds, 1/8000 seconds. 1/4000 seconds, 1/2000 seconds,11000 seconds, 1/250 seconds,1125 seconds,/kloc. Similarly, 1/4000 seconds is one shutter faster than 1/2000 seconds, and so on. For ordinary civilian cameras, the shutter range is at most 1/2000 to 15 seconds, which is also a common range. Most cameras beyond this range can only be seen in more professional cameras. There is also a shutter called B (light bulb), which allows you to decide the shutter length at will, from pressing the shutter to releasing it. Generally, some models of digital cameras also provide B, and single-mirror reflex cameras (whether digital or not) will provide unlimited B shutter options.

(d) In order to obtain correct exposure, the aperture and shutter speed should be well matched. Because the aperture size is directly proportional to the amount of light entering the lens and the shutter speed is inversely proportional to the time when the light acts on the card, for a certain light intensity, the shutter speed should be small when the aperture is large and slow when the aperture is small. As for how to match it better, 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 a portrait, you often want it to be clear and the background is hazy. This phenomenon of "clear portrait and hazy background" is called shallow depth of field. At this time, you have to increase the aperture (with long zoom, the effect will be better). If you want to capture the scenery and draw everything clearly, you must narrow the aperture to achieve a wide depth of field. Because the range of aperture shutter values of general digital cameras is not wide enough, there are sometimes creative restrictions. For example, open the aperture as wide as possible in the sun, but the shutter will become too bright if it is not fast enough to fit. At this time, you have to make a choice, give up too shallow depth of field, or use a filter.

(f) In shutter transportation, common examples include transportation, fireworks, running water and waterfalls. A fast shutter can freeze an instant action, such as jumping up and stopping in mid-air; The slow shutter will have dynamic performance, such as dropping a waterfall on a piece of cloth and so on. Night scenes usually use a slow shutter because you want to have a dazzling light (use a fine aperture to avoid too much light). Shadow water droplets use a fast shutter because they want to solidify and float on the water. In short, different shutter values will produce different effects, and everything depends on your creative inspiration.

(g) Various modes-Generally speaking, there are several modes for intermediate and advanced digital cameras:

First, the aperture first touch mode-you decide the aperture value yourself, the camera will use its metering system to measure light according to your focus, and then give you a shutter value.

Two. Shutter first touch mode-you decide the shutter value yourself), the camera will measure light with its metering system according to your focus, and then give you an aperture value.

Three. Full manual touch-you have full discretion to determine the aperture shutter value. However, many cameras will still provide a display according to your focus, so that you can know if there is any shortage/excess and how many levels, so that you can adjust a suitable lighting combination.

Four. Programming mode-P mode for short. In this mode, the camera will use its metering system to measure the light according to your focus, and then give you an aperture shutter combination. However, you can also choose to change another set of aperture shutter combinations and still have a suitable light value (assuming the metering is correct). For example, the application of photometry is F/5.6,1/60s, which can be changed to F/4,1125 or F/8, 1/30. These three groups of aperture shutter combinations all get the same light value. So some people say that this is a smart fool model.

Verb (abbreviation of verb) EV-card light compensation. Allows you to increase or decrease the light value from the camera. Usually, because there are other external factors that affect the camera's metering, you should increase or decrease the light according to your own experience or the on-site environment. Usually, in the aperture first touch mode, increasing the EV value by one level is equivalent to slowing down the shutter by one level; Similarly, in shutter mode, increasing the EV value by one level is equivalent to increasing the aperture by one level. In full manual touch mode, there is no option to increase or decrease EV, because you can completely control the combination of aperture shutter.

concentrate

(1) Focusing means focusing on the person you want to shoot. Only by focusing correctly can the subject appear clearly in the lens. Imagine that the lens is a pair of eyes. You must focus on something or someone, and then it will be clearly presented to you. Others that are not in focus will be blurred. Basically, a photo of an autofocus camera, regardless of the hand shake factor, must have a focus no matter how shallow the depth of field is, that is, at least one point must be analyzed clearly. If you find that the whole photo is out of focus, it may be one of the following factors:

I. Hand shock

Two. Press the shutter before completing the focusing procedure.

Three. The focal length is too close, which exceeds the camera's closest focus range.

Four. The camera can't find the focus (for example, the sky is cloudy, especially when the weather is bad, it is easy to lose focus, because it involves photometry, which will be discussed in the next part).

(2) In modern digital cameras, autofocus is basically very accurate, and some also provide manual focusing function. But a deeper understanding of the camera's focusing performance can also greatly increase your understanding of this camera. The following are common focusing options for your reference:

First, the method of focusing: almost all autofocus cameras lock the focus by half pressing the shutter, and then press it all. Some well-known cameras will not let you press all the buttons when you can't find the focus, so as to ensure that there must be a focus.

Two. Single autofocus vs continuous autofocus: Single autofocus is a single focus, and the camera will not autofocus until you press the shutter system half-way. Press the shutter for half a minute and don't let go. You can clearly see the situation after focusing from the LCD screen. If you take some pictures with short depth of field (especially macro), you can see the theme clearly. When you are sure that your focus is complete and correct, you can continue to shoot with all your strength. Continuous AF means continuous focusing, and the camera will constantly activate the focusing system to focus on the object it thinks is the most correct. One advantage of continuous operation is that it can further accelerate the focusing speed, because it is continuous operation, which is helpful to compensate the focus of moving objects. But you still have to press half to lock the focus and shoot it all. Continuous power consumption, easy to lose focus, especially in the case of slow focusing speed and high power consumption of digital cameras, it is recommended to generally use single autofocus.

Three. Multi-focus: Photographers used to focus on the middle to shoot composition. In addition to the orthodox and stable photography test, the old automatic camera can only focus on the middle point, which is one of the main reasons. At that time, clever photographers would change the focal length by half pressing. The so-called half-press is to aim at and lock the focus with the midpoint (half-press does not move), then move the camera to re-compose, and then press all the shots. In this way, the focus of locking 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. Imagine that, although the semi-press moving mode can also achieve the effect of "artificial multi-focus", sharp-eyed photographers will find it easy to lose focus, because it is difficult for us to ensure that our camera and the focused object maintain an absolute balance line when moving the camera. In other words, our camera has the opportunity to get close to or away from the focused object after moving. When the depth of field is shallow, it is easy to lose focus. With the emergence of multi-focus, we don't need to move the camera, but choose the focus directly on the camera, which completely avoids the legacy of moving the camera. As for the number of focus points, different cameras have different specifications, generally between 3 o'clock and 9 o'clock. Newly developed cameras (such as new DC, such as G3 and S45 of Canon Digic system) have the function of choosing any point at will, which is really convenient.

Four. Manual focusing: Manual focusing basically does not have the above problems, because it is entirely up to you to control the focusing. The so-called manual focusing of general digital cameras is actually just "autofocus with distance limitation", that is, we actually give the camera the distance of an object, and the camera uses its system to "estimate the focal length". So generally speaking, the manual focusing of digital cameras is not very accurate. Of course, it is another matter to use it in a single-mirror digital camera, because the manual focusing of the lens of a single-mirror camera is really mechanical.

Photometric determination

(1) Light is an important factor to produce images. How to calculate how much light enters the camera will affect the quality of photos. The purpose of setting the aperture shutter discussed earlier is to properly control the amount of light entering the lens, while photometry is to calculate how much light should enter the camera lens to achieve an accurate light value.

(2) In the past, the exposure meter, an instrument for measuring light, was mostly used in the era of manual motors. However, after the emergence of automatic electronic cameras, most cameras have built-in metering systems. To put it simply, the purpose of photometry is to calculate which aperture shutter value is used to shoot, and the photometry is accurate and the aperture shutter value is large enough to be correct, so that the photos taken will be basically correct.

(c) In most electronic cameras, metering is done in a half-press shutter. It can be said that half press is the process of focusing and metering at the same time. In the general light scene, the metering error is basically very small, so we can rely on the camera metering system. However, in some occasions where there is a big contrast between light and dark, such as clear sky and backlight, we should deal with photometry according to our own experience and preferences.

First, for example, when you usually shoot scenery, do you often encounter this problem: the sky I shot is blue and beautiful, but the buildings under the sky are black; It's over, the architectural lighting in my shadow is correct and meticulous, but there are too many the next day, and the blue sky turns white. This is the choice of camera metering. The building is in a clear sky, with great contrast. If you measure correctly for a day, the building will be below; If the building survey is correct, it will end tomorrow. How to deal with it?

Two. For example, when we shoot the sunset, we definitely want a big, round salted egg yolk sun. But in many cases, the effect is only a "pat" field of white light ... what do we do?

Three. For another example, do we shadow portraits often find that the background is brighter than the protagonist, thus making the model a "black-faced god"?

(d) Generally speaking, digital cameras will provide the following four metering modes (different models may have different names):

I. Evaluation (average photometry)

Two. Center weighting point (center focus)

Three. Center weighted average (center key average)

Four. Spot metering (spot metering)

(e) Evaluation (average metering)-The metering area is the average of the whole picture, and different models have different "areas". For example, the camera has the so-called "45-zone average metering", which is to divide the picture into 45 areas on average and finally calculate an average value. This photometric method is mostly used in general landscape photography, because we all hope that the whole landscape picture has the correct luminosity.

(f) Center Weighted Point-Only the center focus is selected as the measurement area. Suitable for macro, portrait and other photography. This metering method should be used in backlight environment, such as portrait photography, to avoid the subject being too dark.

(g) Center weighted average —— Select the center part (about 10- 15% of the whole picture as the metering area). When the composite object is placed in this area, it will be measured correctly. This can be said to be a metering method between average metering and center focusing.

(h) Spot metering-The new camera has multi-point focusing function, and this spot metering method was born. The so-called spot metering means that the metering area follows the focus point, and the user can freely choose the metering area according to the specifications of the camera.

EV-card lighting compensation

(1) The principle of EV has already been mentioned in the section "Aperture shutter", so I won't repeat it here. I want to point out that many times the camera will be affected by the scene environment, and the metering will be incorrect. For example, under the snow, the camera will feel the scene is very bright and provide a low EV value, so other scenes in the photo are easily underexposed.

(2) Some friends like to deliberately add +/-EV to achieve the desired effect. Shadow sunset is an example. You can try to focus on the center, so that the sun is not too strong and eat a round salted egg yolk. Of course, when to add or subtract EV has not been finalized. It depends on your continuous efforts to gain experience! !

White balance (white balance)

1. White balance is a unique but important setting for digital cameras. In fact, there is also the color temperature problem of traditional film cameras, that is, the white balance problem of digital cameras. The traditional film camera does not adjust the color temperature on the body, but adds a color filter to control the color tone in the film selection.

2. In different light, the camera's eyes see different whites. Unlike the human eye, the lens doesn't know how to distinguish white under different light. For example, under yellow light, the white paper seen by the lens is yellow. In this way, we need to tell the camera what is white. This is called white balance setting. Incorrect white balance will make the photo color cast, so you should know how to set the white balance.

3. The white balance of digital cameras generally has the following options (different models have different names or options, but the principle is the same):

Auto- is a fully automatic white balance, which is basically unnecessary, because the camera will automatically adjust it for you according to the scene. Generally, in sunlight, the automatic white balance is very accurate, and there is little color cast, so you can use it with confidence. However, it will be slightly reddish indoors, so you can try other white balances.

Sunlight-refers to sunlight. However, basically, using auto (daytime) makes little difference.

Cloudy-use on cloudy days and clouds to avoid photos being too gray.

Tungsten filament (incandescent)-light bulb, indoor light bulb. Generally, this light will have red and yellow, and red will be corrected with this white balance.

Fluorescent-indoor fluorescent lamp. This color temperature will be blue, and this white balance will be corrected.

Fluorescent H fluorescent tube lamp, similar to the last one, but bluer.

Flash-used when flashing lights.

Custom-Customize the white balance. If the above items fail to find a suitable white balance, you can try to use custom. Use a piece of white paper to tell your camera what is white in the wild. The camera will adjust the color temperature according to the "white" you give it.

One of the advantages of digital cameras is that when you try different white balances, the LCD will display the scene with changed white balances in real time, so you can try it with confidence and try a desirable color temperature to shoot.

focal distance

(a) What is the focal length? The focal length of the lens refers to the distance between the clear image on the central axis of the lens and the CCD/CMOS plane of the film when aiming at the infinite scene. The focal length is usually calculated in mm (millimeter), that is, our common lenses are more or less mm, which involves many optical technologies, so I won't go into details here. At this stage, we just need to pay attention to the same thing. The greater the focal length (mm), the more we get. id=20