Negative! Can’t you open it and look at it after taking it but before washing it? Why?

Negative film

The negative film is the chemical part of the traditional camera. When the negative film is illuminated by light, a chemical reaction will occur to record the image. The structure of the negative film is actually composed of two layers of film on the bottom. It contains some evenly distributed photosensitive particles, which will change when the particles are exposed to light. The situation is just like when we wear a watch in the sun, the skin exposed to the sun turns black, and the longer it is exposed to the sun, the darker the skin becomes. Black. But the position of the wrist and the position where the watch is worn will not be hit by the sun, so a white mark is formed. This white mark is the pattern of the light that the sun shines on us. The principle of the film is the same, except that the photosensitivity on the film Particles can change in a short time.

After the film is exposed, it can be taken to the darkroom for development. Developing means putting the film in, and the developer will change the photosensitive particles that have been exposed to light. It turns black. The stronger the light when it is illuminated, the darker the photosensitive particles will become, which becomes our common negative. The negative needs to be developed before it can become our common photos.

We see it every day Before the photo paper is developed, there is a layer of light-sensitive material on the photo paper. When developing, the negative is placed between the light source and the photo paper. However, just like the projector in the classroom, the projector is the light source and draws pictures. The transparent film is the negative and the screen is the photo paper. When the focus is adjusted, the image of the transparent film will be projected onto the screen. The difference is that the photo paper contains photosensitive materials, which will react chemically when exposed to light. Leave the image on the photographic paper.

The difference between color film and film is that it has three different layers of photosensitive particles. The three layers of particles react to the three primary optical colors of red, green and blue respectively. In the development stage, the The liquid will dye the three particles into different colors. When the three layers of particles overlap, a colored negative film will appear.

Image

After the light passes through the lens, the image will appear on the negative film Imaging. You can notice that the lens will invert the image on the film up, down, left and right, so the films we usually see are also inverted left and right. But during the development process, when the film is dried on photographic paper, The image will be reversed again. Therefore, the image seen on the photo paper is in the same direction as the actual object.

Shutter

The shutter is the switch for taking pictures. When the picture is not taken, the inside of the camera The shutter blades are closed tightly, so the film is not exposed to light. When the shutter switch is pressed, the shutter opens and closes rapidly. At this moment, the film has sensed the light and recorded the image.

Since light can darken the film through development, it is very important to control the light entering the camera body in order to effectively record the image of the object. Too much light will completely turn the film into black. Dark, just like a film that has been exposed; too little light will make the image too dark after the photo is developed.

One way to control the intensity of light is to control the shutter opening time. The longer the shutter start time, The longer the time, the brighter the photo image; the shorter the shutter opening time, the darker the photo image. However, the shutter speed of a disposable camera cannot be adjusted. The shutter speed is limited by the pulling force of the slingshot (3d). The greater the pulling force, the shutter will open. The faster the speed.

The principle of opening the shutter of a disposable camera is that when the film is rotated, the control lever (3b) will move to the left. When the shutter button is pressed, the shutter will be pressed down. Simultaneously push the control lever to the right. At this time, the control lever will sweep across the shutter blade (3c), causing the blade to move downward and open the shutter. Since the control lever only sweeps the blade, after the control lever leaves the blade, the blade will move It is pulled back to its original position by the tension of the slingshot (3d), covering the aperture.

Aperture

The lens collects the light source reflected from the subject. When the shutter is opened, the light source passes through the aperture. It can reach the film and expose it. The aperture of most cameras is adjustable. The larger the aperture is opened, the more light can enter the film, and the final image on the photo will be white. On the contrary, when the aperture is opened small, The light that can enter the film is relatively soft, and the final image on the photo is dark. When using a normal camera, photographers usually adjust the aperture and shutter to control the exposure rate to create the most ideal image in different light and dark environments. Effect.

However, the aperture of a disposable camera cannot be softened. For a disposable camera, the aperture is just a hole that allows light to pass through. The size has been determined when the camera was produced. Limited. Since it cannot be adjusted, manufacturers have carefully studied the shutter speed and aperture settings to determine the most suitable combination for use in general situations. Disposable cameras are suitable for use in most situations.

Lens

The lens is a piece of transparent plastic or glass with a curved surface. Its function is to form an image of the light reflected from the object, and then refract it onto the film. It is disposable after use. The lens of the camera is made of resin.

The principle of refracting light through the lens is very simple. The light travels faster in the air than in the lens. The situation is just like tilting a shopping cart. Just like pushing onto the grass, if the left wheel of the car is pushed onto the grass first, the speed of the left wheel will slow down; since the speed of the right wheel remains unchanged, the shopping cart will turn to the right until the right wheel is pushed onto the grass. Then walk in a straight line. The same goes for the progress of light. When the light enters the lens, it will be refracted, that is, change its direction.

Most of the lenses used in disposable cameras are wide-angle lenses because they are used The focal length of a disposable camera cannot be changed, and the characteristic of a wide-angle lens is that it can photograph objects from very close to infinity; therefore, as long as the object being photographed is beyond the distance specified on the box, the disposable camera can be used in many different situations. Used in situations.

Viewing window

When taking pictures, the naked eye aims at the photographed object through the viewing window. Since the disposable camera does not capture the objects captured by the lens, The image is directly refracted onto the viewing window, so the scenery seen in the viewing window will be slightly different from what is captured by the lens. In order to improve this error, the viewing window of the disposable camera is made into a curved surface. Mimic the image in the lens.

Body (camera obscura)

The main body of the camera is an opaque box that not only blocks light to store the film, but also acts like a stand. form other parts.

Flash

When we hold the camera to shoot, we will inevitably have hand shake. If the light changes during the exposure of the film, the image will be blurred. Therefore, the shutter opening time is very short. (Usually one hundred and twenty-fifths of a second). But in low light conditions, such as at night or indoors, this exposure time is not enough to form a clear image, so we have to use flash to increase the reflection of the subject. The light to the camera.

Disposable cameras do not require electronic control, so all the electronic parts seen in the picture are used to control the flash. In general, the circuit that controls the flash It is an open circuit, that is, it cannot allow current to pass. But when the shutter blade made of metal is opened, it will hit a piece of metal on the circuit, forming a closed circuit. The current will be connected immediately, and the flash will flash according to the shutter time. .

Capacitor

This thing that looks like a battery core is called a capacitor. Its function is similar to that of a battery core. It is used to store energy and then release it. Different The battery core uses chemical principles to release energy evenly and gradually. The capacitor is like a battery that stores external energy, but when it is placed in a closed circuit, it will release the stored energy at once. All electric energy is released. This feature is very suitable for use in flash lamps, because the brightness of the flash lamp is very high, but it only needs to flash for an instant. Therefore, part of the electric energy of the battery core must be stored in the capacitor first, and then the flash lamp can be flashed again.

Flash start button

Before using the flash, you must first press this black button, and then press the power storage button on the circuit board to cause the capacitor to flash and start charging. But the flash After that, the electric energy in the capacitor will be completely extracted. If you don't press the flash start button before pressing the shutter next time, there will be no flash.