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英国essay代写:Control technology of photographic flash

2019-11-07 | 来源: 51Due教员组 | 类别:Essay代写范文

本篇essay代写- Control technology of photographic flash讨论了摄影闪光灯的控制技术。闪光灯也称为独立式闪光灯或离机闪光灯,有两种类型。常见的闪光灯从正面来看,其上面为闪光部分,下面突出的部位称为闪光灯插座,是连接照相机机身的地方。纯手动式闪光灯每次闪光的持续时间都是一样的。自动调光式闪光灯则是闪光灯本身带有测光元件,它能根据从被摄体反射回来的光线,自行调节闪光灯的输出。专用闪光灯是指专门为特定型号的照相机设计的闪光装置,只能用于某种系列的照相机上。其特点是要与指定的照相机配合使用,才能充分地发挥闪光灯和照相机的作用。本篇essay代写51due代写平台整理,供大家参考阅读。

Flash is also known as independent flash or off-camera flash, which can be divided into two types: one is a general type of camera that can be used by different manufacturers; the other is a special model used for a specific camera. The use of flash technology can have a great impact on the photographic effect.

A common flash is seen from the front. The top part is the flash part, and the protruding part, called the flash socket, is where the camera body is connected. The duration of each flash of a pure manual flash is the same. An auto-dimmer flash is one with a light meter that adjusts its output according to the light reflected from the subject. Special flash is a special flash device designed for a particular type of camera. It can only be used on a certain series of cameras. It is characterized by the need to cooperate with the designated camera, in order to fully play the role of flash and camera.

In the viewfinder of the camera, an indicator light will emit light while the flash is charging. If another indicator light also shines before each shot, it is enough light to hit the subject. Special flash and camera combination system can complete some or all of the above functions, now has gradually developed into a convenient and practical camera series. In addition, there are many special purposes of special flash, such as underwater photography underwater flash, macro photography ring flash, etc.

Flash synchro is the flash that occurs when the shutter of a camera is fully open, so that the whole picture is evenly exposed. Since the flash duration is very short, flash synchronization must be achieved during exposure, that is, the flash process must be completed between the shutter opening and closing. Flash sync speed is when the camera opens all the shutter blades so that the subject is evenly illuminated. A DSLR camera with a shutter has a flash synchronization speed for the photographer to choose when using the flash. When using flash, select shutter speed lower than flash sync speed, not higher than flash sync speed. When shooting below the flash synchronous speed, the picture can be uniformly exposed and complete. The picture taken when the speed is higher than the flash synchronizing speed will be exposed unevenly because the part is not illuminated by the flash.

Intermirror shutter since each shutter is fully open when the flash is exposed, a picture taken with any speed shutter can be evenly sensitized. Therefore, there is no synchronization speed, from the highest shutter speed to the lowest shutter speed.

The flash index is an indicator of the amount of light emitted by the flash. The higher the flash index, the more efficient the flash. The flash index value marked on the flash lamp is the flash index when shooting with ISO100 film, which is denoted by GN. The relationship between the aperture coefficient, flash index and flash distance can be expressed by the following formula: flash index = aperture coefficient × flash distance.

Many pure manual flash units have a table on the back, indicating the aperture coefficients used at different distances for different sensitivities, for the photographer's reference. Depending on the sensitivity and flash distance used, the required light can be detected. To ensure correct exposure, the operator sets the aperture on the lens according to the distance being shot. In the estimation of the aperture used, it is better to have more than less. In other words, it is better to be overexposed than underexposed. If there is natural light and the flash is used only as an auxiliary light, do not overexpose the flash.

Direct camera flash is when the flash is placed on or next to the camera and flashes at the subject. This is a common flash shooting method. The method has the advantages of simple operation, flexible use, easy mastery, bright light effect and high image definition. Its drawback is smooth smooth effect stereo sex is poorer, the background that leaves main body relatively close can produce those who make a person dislike "black shadow is annulus", after be bright before dark receive light uneven, smooth face is reflected show dazzling bright spot, take color photograph to be able to produce "red eye effect". The "red-eye effect" occurs when the blood vessels behind the retina of the subject reflect a flash of light that causes the pupil to turn red, a phenomenon that is more likely to occur when the scene is dark and the camera is facing up. There are two ways to avoid the red-eye effect: avoid using flash photography in total darkness; 2 it is to avoid as far as possible front flash illume, if make the line of sight of flash lamp and the person that take photograph becomes certain Angle, can avoid the point-blank reflection spot on pupil.

Lateral direct flash is when the flash is located on the side above the camera and flashes directly at the object being photographed. There should be a long flash line when using. The advantage of this method is that it can overcome the disadvantage of direct flash. The disadvantage is that it is cumbersome to operate.

Direct diffuse flash is to add milky white soft light piece to the flash lamp, or cover with white fabric, flash directly to the object being photographed. This method can be used in both position and side. The flash effect of this method is gentle and suitable for photographing portraits of children and women. Because the mask on the flash blocks some of the light, turn up the aperture.

Flash is to flash a flash of light onto a reflector, such as a ceiling or wall or reflector, so that the reflected light illuminates the object being photographed. The advantages of reflective flash can not only overcome the disadvantages of direct flash, but also the light is soft and natural. Its disadvantage is small power. This method cannot be used for flash that cannot rotate the lamp holder.

The individual flash of the auxiliary flash is caused by the flash of the fixed flash on the camera. Because many digital cameras require two flashes to take a picture, these secondary flashes, which have been set up, will only flash when the second flash of the camera's flash is over. An auxiliary flash unit can also be used as a stationary flash unit, which has more power than a stationary flash unit, and can rotate the head for a top-up flash to eliminate shadows.

In a word, the mastery of the modeling and ideographic function of light in photography is the mastery of the skills of light. Light is not only the premise of lighting, but also the important condition and factor of composition and modeling.

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