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Fundamentals of photography technology (1)

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2003-5-23

order

Nowadays, photography has become a fashion. No matter on the street or in the vast countryside, we can see many people carrying "long guns and short guns" to take pictures. There are many masters who are creating, but more are ordinary photographers. But there are many fans and few excellent works. The reason is that many novices have no idea and shoot blindly without good basic skills, which leads to disproportionate pay and gain. Below, let's seriously study the basic skills of photography.

compilers

E-mail:E-mail:yaozengxiang@sina.com QQ:68 1227 19

Chapter 1 Introduction to the camera

At present, cameras on the market can be divided into two categories, one is traditional film camera, and the other is digital camera, which is what we usually call digital camera.

Next, we mainly discuss the traditional camera.

In traditional cameras, according to their framing methods, they can be divided into two categories, one is a paraxial framing camera, and the other is a single-lens reflective camera. The cameras we will discuss in the future refer to 35mm single-lens reflex cameras unless otherwise specified.

Paraxial cameras view through a small window next to the lens, so there is a viewing error (parallax), that is, what we see through the viewfinder is not exactly the same as what we can actually shoot. Its characteristic is that the farther the distance, the smaller the error; The closer the distance, the greater the error.

A single-lens reflex camera takes a view through the lens (when the shutter is pressed, the reflector bounces up and the viewfinder turns black temporarily. ), there is basically no error in framing (that is, what we see is basically the same as what we can actually shoot), and it is an advanced camera. Another advantage of this camera is that users can easily change different lenses according to their own needs as long as the interfaces match. Because the single-lens reflex camera has incomparable advantages over the two paraxial cameras, it is deeply loved by photographers.

Chapter II Scientific Use of Cameras

Camera is a precise optical imaging tool, which is complex in structure and expensive, but easy to be damaged. We should cherish it, but this happens from time to time because users don't know it or are careless at the moment, or even fiddle with it without knowing it.

Next, let's talk about how to protect our camera:

First, dustproof-dust may damage the camera and lens after entering the camera, shorten the service life and bring hidden dangers to the normal use of the camera. So we'd better wear UV lens for a long time and put the camera in a dusty place.

Second, waterproof-when taking pictures on rainy days and by the sea, be careful not to let water splash on the camera (especially seawater); When shooting near fountains and waterfalls, pay attention to the wind direction and don't let water droplets splash on the camera.

Third, shockproof-sometimes we don't cover the camera, the camera collides with other hard objects, or the user accidentally drops the camera, which may cause the camera to be damaged.

Fourth, prevent violent cracking-the operation of the camera should be gentle, not hard to press, in case of hidden damage caused by accumulation. Improper operation may even damage it on the spot.

5. Anti-Mars-When shooting electric welding, fireworks and firecrackers at festivals and weddings, we should pay attention to prevent splashing sparks from splashing on the camera and burning the lens and fuselage.

Six, moisture-proof-if the camera is placed in a humid environment for a long time, it may cause the lens to be moldy, reduce the luminous flux, and produce a large number of mildew spots, which can not be used (especially when the mildew spots grow in the middle of the lens). And too much humidity will corrode the electronic components inside the camera.

Seven, anti-exposure, anti-high temperature-modern cameras are generally equipped with TTL built-in metering device, the lens facing the scorching sun for a long time will seriously damage the camera's metering system, leading to the aging of metering elements and the decline of metering accuracy. Some high-end cameras also have a large number of electronic components inside. Exposure to the hot sun will lead to a sharp rise in the temperature of the camera, which will lead to a decline in stability and reliability, or even temporary unavailability (but generally will not cause permanent damage).

Fundamentals of Photography Technology (2)

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2003-5-23

Chapter III Introduction of Commonly Used Technical Terms

Focal length-the distance from the center of the lens to the focal point. The unit of focal length is usually expressed in mm, and the focal length of the lens is usually marked in front of the lens, such as f=50mm (this is what we usually call "standard lens"), 28-70mm (our most commonly used lens), 70-2 10mm (telephoto lens) and so on.

Aperture-A device used to control the amount of light passing through a lens.

Shutter-A device used to control the exposure time. Shutters can generally be divided into curtain blinds, lens blinds and steel blinds. Among them, curtain blinds can be divided into vertical curtain blinds and horizontal curtain blinds. Steel shutter can reach higher speed (the highest shutter speed can reach112000 seconds or more at present). Generally, the highest speed of the inter-mirror blade shutter does not exceed 1/500 seconds, but the biggest advantage of the inter-mirror blade shutter is that the noise generated during shooting is extremely low, which is very conducive to sneak shots and can realize synchronous flashing within the full speed range.

Shutter speed-the time when the shutter is open. It refers to the time (exposure time) when light sweeps across the film. For example, "1/30" means that the exposure time is 1/30 seconds. Similarly, "1/60" means that the exposure time is1/60s, and the shutter of1/60s is1/30s. The rest and so on.

Note: Some materials refer to shutter speed as shutter time. The two names are different, but they mean the same thing, both referring to the shutter opening time.

Depth of field-the relatively clear range of an image. The depth of field depends on three factors: the focal length of the lens, the distance between the camera and the subject, and the aperture used. The relationship between depth of field and the above three factors is: the longer the focal length, the shorter the depth of field; The shorter the focal length, the longer the depth of field (for example, under the same aperture and distance, the scene of 28mm lens is far greater than that of 70mm lens); (2) The closer the distance is, the shorter the depth of field is, and the farther the distance is, the longer the depth of field is (for example, under the same focal length and aperture, the subject scene at 10 m is far greater than the subject depth of field at 1 m); (3) The larger the aperture, the shorter the depth of field, and the smaller the aperture, the longer the depth of field (for example, under the same focal length and distance, the scene with the aperture of F 16 is far greater than the depth of field with the aperture of F4).

Sensitivity-indicates the speed of the photosensitive material. The unit of sensitivity is "degree" or "fixed". For example, "ISO 100/2 1" means a film with a fixed sensitivity of 100/2 1. The higher the sensitivity, the more sensitive the film is (that is, the less light is needed to shoot the same photo normally in the same shooting environment, that is, a higher shutter or a smaller aperture can be used). The sensitivity of 200-degree film is twice that of 100-degree film, and that of 400-degree film is twice that of 200-degree film, and so on.

Color temperature-Different pigments contained in different kinds of light are called "color temperature". The unit of color temperature is "K" (Kelvin). The color temperature we usually use is 5400 K-5600 K; The color temperatures that light types A and B can adapt to are 3400K and 3200K respectively. Therefore, different types of films should be selected according to the subject and environment, otherwise there will be color cast (unless the color temperature is corrected by color filter).

Attachment: Definition of color temperature "Suppose there is a black metal in an environment of minus 273 degrees (absolute zero). With the increase of temperature, black metal will emit light with different wavelengths, and the metal color temperature corresponding to colored light plus 273 is the color temperature of light. " For example, when a metal is heated to 2500 degrees Celsius, it will emit red light, and the color temperature of this red light is "2500+273" K, which means that the color temperature of this red light is 2773 K. The lower the color temperature, the higher the percentage of long-wavelength light (red and orange light). The higher the color temperature, the higher the percentage of short wavelength light (blue light and purple light). For example, the color temperature of sunlight at noon is about 5500 K; The color temperature of the flash is about 5600 k; The color temperature of the blue sky is about 20000 k; 100 watt light bulb's light color temperature is about 2600K K.

Exposure-the process by which light reaches the surface of the film and makes the film sensitive. It should be noted that by exposure, we mean film exposure, which is a necessary process for us to obtain photos. This is very different from what non-professionals call "exposure". What they call "exposure" refers to the accident that the camera leaks light and causes the film to fail.

Relative aperture-the ratio of the effective aperture (beam diameter) of the lens to the focal length. The larger the relative aperture, the faster the lens speed. Such as 1:2.8, 1:3.5-4.5, etc. Among zoom lenses, lenses with fixed relative aperture are generally called professional lenses, lenses with fixed relative aperture but between 1:2.8- 1:4 are called quasi-professional lenses, and the rest are called mass lenses.

Exposure combination refers to the combination of different apertures and shutters that can be used in the same shooting environment. For example, the shutter measured by the exposure meter is 1/30 seconds, and the aperture should be 5.6, so F5.6 and 1/30 seconds are an exposure combination. We can also use the exposure combination of F4 and 1/60 seconds instead, and we can also use the exposure combination of F2.8 and1125 seconds instead. In other words, these combinations are equivalent. However, it should be noted that although these exposure combinations are equivalent, that is to say, the exposure is accurate, but the depth of field obtained by different combinations is different.

Fundamentals of Photography Technology (3)

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2003-5-23

Chapter IV Basic Photography Technology

The first section photographic light

How can I take a good photo? The correct use of light is a crucial link.

Next, let's discuss how to use up the light according to the situation.

First, under normal circumstances, we can obtain high photometric accuracy by relying on the built-in exposure meter of the camera, and we can make exposure according to the reading of the exposure meter.

Second, backlighting photography: when backlighting photography, if you still follow the readings of the exposure meter, the exposure will be seriously insufficient, leading to shooting failure. If you shoot in the outdoor sun, you should increase the exposure by 3-4 levels according to the exposure at that time; If you want to take a silhouette effect, you should expose it according to the brightness of the background. In order to make the dark side have a certain illumination, we can use the reflector to reflect the light and determine the exposure on this basis.

Third, cloudy photography: if you can't determine the accurate exposure when shooting on cloudy days, you should be biased towards slight underexposure; Moreover, even if the exposure of cloudy photography is accurate, in many cases it is often not as good as a little less exposure. Because the exposure is slightly insufficient (the exposure is reduced by 0.5- 1), the performance of the bright part and the bright part of the object irradiated by diffuse light on cloudy days will not be affected, but it will help the dark part and the dark part to increase the tone contrast and slightly increase the tone contrast of the whole picture.

4. Bracket exposure method: In order to obtain ideal contrast and rich texture levels, bracket exposure method (or exposure optimization method) may be used for portrait photography, landscape photography, especially advertising photography or still life photography. The specific operation is: shoot 1 sheet according to the measured or estimated correct exposure, and then shoot 2 or 4 sheets according to the level of exposure increase or decrease, just like putting brackets on both sides of the reference exposure to gradually change the exposure. For example, according to the reading of the exposure meter, after shooting with F81125 seconds, shoot with F8 1/60 seconds and F 1 1/250 seconds, and then choose the most ideal one. This method seems to be a waste of film. In fact, getting an ideal negative is far more valuable than wasting a few films. In addition, several other films with slightly different exposures can be kept as backup negatives.

Section 2 Photographic Composition

Photography is inseparable from composition, and the quality of a work depends largely on composition. Next, let's discuss how to write a composition according to the situation.

First, the landscape portrait photos

Portrait taken in combination with landscape is called landscape portrait photography, which belongs to a variety of portrait photography. If the scenery is mainly represented, people appear very small on the screen and become the foil of the scenery, which belongs to landscape photography. Therefore, taking a portrait of a landscape, whether it's taking a picture to commemorate or creating a photo, may seriously affect the effect of taking a picture or the expression of god if you take a picture of a person far and near, although you can see the figure but can't distinguish the face. So, you should take people closer and bigger.

So pay attention to the proportion of the picture when shooting. Generally speaking, a full-length portrait is equivalent to 1/2-3/4 of the lateral height, a large bust is equivalent to 2/3-3/4 of the lateral height, and a bust is equivalent to 3/5 or even 4/5 of the lateral height. (When shooting a bust, it is strongly recommended that you keep the eyes of the subject below the top of the picture 1/. In any case, a person's head should have a proper amount of space from the top of the picture, so that it looks harmonious and has a certain degree of comfort, and it can't give people a sense of oppression.

Second, landscape photography

Many people like landscape photography, and sometimes even travel long distances to create, but the result is not ideal and they can't get the effect they need. It seems that what they saw and what they actually filmed are two different things.

What is the reason? Not paying attention to composition-this is a very important reason for failure. So, what should be done specifically?

First of all, you should make clear what you want to shoot and what you want to show, and then make a composition according to your shooting intention. Except for special needs, the picture composition should generally be balanced, otherwise there will be deviation or a sense of instability. Or although the imbalance is equal, it should feel balanced visually. In order to balance the picture, we can not only use symmetrical composition or layout through the leverage of picture perspective, but also use the leverage and stability of visual psychology-one or two presses to achieve balance. For example, the left part of the picture is a towering mountain peak, the lower right part of the picture is the water surface, and the upper part is the sky. Due to the strong contrast between the scenery and its hue, the picture appears to be left-handed and right-handed, and the composition is very harmonious. Suppose there is a sail shadow on the water in the lower right part of the picture, or an eagle in the sky in the upper right part of the picture. Even if the sail shadow or eagle is far away and small, it is insignificant compared with the mountain, but the emphasis on the mountain in the left part of the picture will disappear and the composition of the whole picture will appear balanced.

For another example, the upper right part of the picture is a building or a towering mountain peak, and the lower left part of the picture is a vast green space. This picture is obviously top-heavy (upper right) and light (lower left), which is unbalanced. If the perspective is chosen properly, it will show a group of cattle and sheep on the green land or a group of children playing on the grass. Although cattle, sheep and children themselves can't achieve substantial balance with the building, due to the layout corresponding to the physical objects, they have a balanced composition with considerable weight, so that the picture doesn't seem to be light on the left and heavy on the right, thus achieving visual balance.

Pay attention to the contrast of the picture while maintaining the balance of composition. Sometimes, in the scenes we want to shoot, some have high brightness and some have low brightness (very dark), which will make the camera's metering system notice one thing and not see another: if exposed, the dark part will be very dark and have no sense of hierarchy; If you press the dark part to expose, the bright part will be white and lose the details. Before dealing with this problem, it is necessary for us to understand the photographic characteristics of films: each film has a exposure latitude, that is, how much overexposure or underexposure is allowed. Ordinary daylight film can be overexposed to level 3, but only to below 1 level. Beyond this limit, the scene will lose its hierarchy. Therefore, when we encounter a scene with great contrast, we should take care of the dark parts as much as possible, that is, first measure the light according to the bright parts, and then add 2-3 exposures on the basis of the measurement. In this way, although the bright part is overexposed, it takes care of the dark part, which greatly enriches the level of the dark part. Although the level of the bright part is lost, it still has a considerable level and will not affect the whole picture.

In addition, pay attention to the control of depth of field when composing. For example, our subject is a Bai Lianhua, so we should use a large aperture to get a small depth of field, and blur the scenery before and after the lotus to highlight the main body (lotus). If we shoot a landscape, we should use a small aperture to get a large depth of field, so as to highlight the beauty of the landscape. For example, as shown in the following figure:

One more thing must be noted-don't save trouble without using a tripod. Using or not using a tripod sometimes even determines the success or failure of a work (especially when using a telephoto lens), because a good work usually needs to be enlarged, and the slight jitter may not be visible in a small photo, but once enlarged, the traces of jitter will be revealed. A better solution is tripod+cable release.

Fundamentals of Photography Technology (IV)

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2003-5-23

The use of the third quarter lights

Use of flash lamp

The electronic flash is sometimes called the perpetual flash. The illumination is high, but the illumination time is short (the illumination time is about 1/5000- 1/2000 seconds, so the shutter has no control effect on the flash. ), can be synchronized with the high-speed shutter (except curtain shutter and steel shutter), and can flash continuously, which is convenient for quick photography. It is the most used artificial light source.

Flash is a point light source, so the intensity of illumination is directly affected by the illumination distance, that is, the farther the illumination distance is, the weaker the illumination is (the degree to which the subject directly receives light).

We can use the flash by first determining the distance between the subject and the camera, and then calculating according to the formula "Flash Index (GN)/ Distance between the subject and the camera (M)= Applied Aperture (F)" to get the aperture that should be used at that time. For example, if the flash index is 24 and the distance between the subject and the camera is 3 meters, then we should use F8 aperture (24/3=8). Of course, we can also determine the aperture used in shooting first, and then convert the above formula into "flash index/aperture used = shooting distance" to determine the shooting distance.

(Note: ① The flash index is generally printed on the back of the flash; ② When using the flash, the shutter speed cannot exceed the maximum synchronous shutter speed supported by the camera, but the mirror shutter can be synchronized with the flash at any shutter speed; ③ Don't flash at the baby's eyes at close range, otherwise it may hurt the baby's eyes and cause serious consequences. )

How to master night scene exposure

Because the calculation of night scene exposure is complicated, it is not appropriate to discuss it in detail here.

The following only provides partial exposure (the following data are based on ISO 100/2 1 film) for your reference:

Shooting object

general situation

Applicable aperture

duration of exposure

Urban night scene

Take a big picture from a height.

5.6

1-2 minutes

Unique street view

The distance is 20-30 meters.

5.6

1/8 seconds

Bright windows

Large-scale store merchandise display window

5.6

115 seconds

neon-light advertisement

Distance 30-50 meters

5.6

1/30 seconds

Lighting fountain

Distance10-20m

four

1/30 seconds

A floodlit court/field

Distance10-20m

four

1/30 seconds

Lighting construction site

The distance is about 500 meters.

5.6

1-2 minutes

Night view of Lantern Festival

Distance 50- 100 m

5.6

1/4 seconds

Festive fireworks

Show the complete flower shape of fireworks

eight

1-2 seconds

Clear sky and bright moon

Shows the shadow level of the moon and the surface.

1 1

1/60s

Clear sky stars

Show the trajectory of the star.

1 1

1-2 hours

Summer night lightning

Show the complete form of lightning

eight

1-2 seconds

Summer night market

Towns are usually small cities at night.

four

1-2 seconds

Indoor fluorescent lamp

Take pictures of ordinary people

four

1/4 seconds

There is no uniform law to follow when shooting night scenes. Readers can use the above data as a reference, and the specific operation can be adjusted appropriately according to the actual situation, so they can master it flexibly without copying it mechanically.

Fundamentals of Photography Technology (5)

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2003-5-23

The fifth chapter photography skills

Usually we see many photos with special effects and learn to imitate them when we see them, but the effect of our works is often far from that of the imitators.

So, how can we shoot our own unique photography?

Below, we will tell you how to shoot trick photography through several examples. You can draw inferences and make your own stunts.

Example 1: Multiple exposures-two or more exposures are made on a film, and a picture with relevant connotations is formed by using two or more images. This method of photography is called multiple exposures. Generally, we use a mask (or black paper) for composite photography: using a mask, first cover half, make an exposure, then cover the other half, and make another exposure, thus completing a multiple exposure. Or there is a big difference between the light and shade of the subject, so we first record the position of the dark part, and then take the bright part as the exposure standard for an exposure. After that, according to the specific position of the recorded dark part, we re-exposed it by using the area of the dark part (which was basically unexposed at the first exposure), which can also achieve the purpose of multiple exposures.

Example 2: Zoom slow exposure-Sometimes we see some photos, the scene in the center of the picture is clearly imaged, and the images around the picture are gradually blurred, showing a radial modeling effect, forming an explosive movement, or some photos are taken on holiday nights to form radial light lines, resulting in strong depth vision. We can take photos with similar special effects by using the method of slow exposure when zooming. The operation points are as follows:

(1) Fix the camera on a tripod;

(2) Put the main body in the center of the frame;

⑶ Set the focal length of the zoom lens at the longest end;

(4) Release the shutter when zooming. It should be noted that the speed and time of zoom process and slow exposure process should be consistent. If the exposure is 2 seconds, the start and end of the zoom operation should also be 2 seconds; It should also be noted that the action should be even, and never let the camera vibrate, otherwise it will easily lead to shooting failure. It is suggested to control the shutter by releasing the cable (this method is difficult and the success rate is not high. I hope you can practice after you are proficient.

Example 3: Simulated night shooting-For example, when we see the sunset in the west by the river, we want to take a picture of the artistic conception of "a setting sun sprinkled in the water, half river rustling, half river red". Then, we can reduce the normal exposure by 3 levels (artificially underexposed). In this way, the picture of the photo will tend to be orange-red and have the taste of sunset. If you add one or two sails, the effect will be even more wonderful. (Note: To be on the safe side, it is best to adopt Chapter 4 "Exposure in Parentheses"). As shown in the figure below:

Example 4: Artificial reflection-For example, we sometimes see a scenic spot that is very suitable for taking scenery, but the fly in the ointment is that there is no reflection. At this time, we can put a mirror in the front and bottom of the lens and adjust the position appropriately, so that we can "create" a reflection (this method is especially suitable for shooting city night scenes).

Example 5: Ultra-close-up shooting-Sometimes, we need to shoot some tiny objects at close range, but most beginners don't have close-up equipment. At this time, we can use some special methods to achieve our goals. You can even shoot a 2mm ultra-close lens by the following methods: (1) First remove the lens of the single-lens reflex camera; (2) Hold the lens with the left hand and the fuselage with the right hand; (3) Inverted lens; (3) Adjust the distance appropriately (move the camera back and forth) until the image is clear, and measure the light (at this time, the camera's metering system is still effective); (4) Shoot and complete the operation. Note: When shooting at ultra-close range, due to the short distance and extremely shallow depth of field, try to narrow the aperture to obtain a longer depth of field. In addition, because the camera body and lens are separated, it is difficult to grasp, it is difficult to hold the camera firmly, and it is easy to shake, so it is necessary to adjust the shutter speed appropriately. The most important thing is: don't be impetuous. Please keep this in mind.

Example 6: Slow shutter shooting technology-We can use high-speed shutter to fix fast moving objects. On the other hand, we can also use the characteristic that the low-speed shutter can't fix the high-speed moving object to get motion. For example, if we want to shoot the vehicles on the expressway, when shooting with the low-speed shutter of 1/8 seconds, it will be a bit blurred when "freezing" with the high-speed shutter of 1/8 seconds, but the background is still, so it is clear. In this way, a dynamic and static contrast is formed, and a strong sense of movement is formed, which leaves a deep impression on people; For another example, if we take a night view of the city at night and expose it for a long time with the B gate or the T gate, the lights of the car will be pulled into a line. Pedestrians and others will only leave shadows because of long exposure, while urban buildings and other scenery are fixed and clear, thus forming a very beautiful night view of the city. Also, when shooting waterfalls in landscape photography, use a shutter slower than 1/4 seconds, so as to show the attractive charm of waterfalls, such as clouds, as shown in the following figure:

In short, there are countless examples. It is important for beginners to practice more and sum up experience in practice. Only in this way can they improve themselves and surpass themselves!

What I mentioned above is the author's experience. Of course, due to my lack of experience, I would like to ask readers to teach me more about mistakes and omissions. I am very grateful!