Commonly used movie models

Film type: There are black-and-white film and color film for photography, which are divided into 120 film and 135 film according to different sizes.

120 film can take photos of different sizes according to different 120 cameras, including 16 negative (the frame is 4.5× 6 cm); Shoot 12 negative (6× 6 cm); There are also 10 negatives (6×7 cm) and 8 negatives (6×9 cm). The length of 120 film is generally 8 1-82.5cm, and the width is 6.1-6.5cm.120 film. How many negatives are taken depends on the camera model.

135 film is suitable for all types of 135 cameras. A roll of 135 film can shoot 36 negatives, with a picture size of 24×36 mm The length of 160- 170 cm and the width of 135 film are generally 3.5 cm. This film has regularly arranged holes on both sides.

Black and white film: according to the sensitivity to color, it is divided into panchromatic film, dichroic film, color-blind film, infrared film, X-ray film and so on. We often use panchromatic film, which can show various colors of nature in different shades of black, such as red, orange, yellow, green, cyan, blue and purple. In other words, it is sensitive to all visible light. In addition to blue and purple in visible light, the color separator can also feel yellow and green, but not red. This kind of film is often used for printing plate making and sometimes for landscape photography. Color-blind films are sensitive to blue-violet light in visible light, but very insensitive to green light and red light. This kind of film is suitable for black pattern, chart and text remake. Infrared film, specially used to feel light with longer wavelength than red light, is generally used in aviation and military photography.

Sensitivity of film: sensitivity is the sensitivity of film to light, and it is also the photosensitive ability and symbol of film. Film can be sensitized in weak light, which is called high-speed photosensitive (fast) film; On the contrary, films with low sensitivity should be shot under strong light. When films with different sensitivities are shot under the same light, the aperture or shutter speed of the camera should be changed, that is, films with high sensitivity should have smaller aperture and faster shutter speed. Low-sensitivity film, on the other hand, has a larger aperture or a slower shutter speed.

According to the sensitivity, it can be divided into fast film (above GB24), medium-speed film (GB2 1) and slow film (below GB 18).

Sensitivity has many names, and the common ones are American ASA system and German DIN system ("fixed" system). China adopts GB (national standard) system, which is equivalent to DIN system.

China's GB national standard system will double its sensitivity for every GB3 added. For example, the sensitivity of GB24 film is twice that of GB2 1 film. Various sensitivity standards can be converted to each other. ASA 100 is equivalent to GB 2 1 or 2 1DIN.

Selection of black and white film: How to choose low-speed, medium-speed or high-speed film depends on different requirements such as shooting object, shooting conditions and final photo magnification.

In general, when shooting outdoors, the light conditions are good, the brightness of the scene is high, and the contrast is also high, so it is more appropriate to choose 2 1DIN medium-speed film. If the contrast of the scene is flat, you can choose a low-speed film with a slightly higher contrast.

When shooting indoors, if the subject is dynamic, whether using natural light or lighting, we should choose a film with high sensitivity to avoid affecting the image level due to insufficient exposure or blurring the image of dynamic objects due to too long exposure time. When shooting with flash, generally choose 2 1DIN or film with higher sensitivity, so that not only the sensitivity index can be larger, but also its tolerance is large because of high sensitivity, which will not cause excessive contrast of the negative film.

In sports shooting, it is generally not suitable to use flash. Sports shooting is dynamic, so we should choose films with high speed sensitivity (such as 24DIN and 27DIN).

Generally speaking, stage photography should not use flash, but must use film with higher sensitivity.

Shooting portraits, still lifes and landscape photos requires rich layers, delicate silver lines, strong texture and pleasing colors. Try to use low-speed and medium-speed films.

Color film: color film for photography includes color negative film and color reversal film.

Color negative, after being developed, the color on the negative (negative) is the complementary color negative of the original color. Color negative is mainly used to make color photos; And you can print and play black and white photos directly, but the level and contrast of photos are affected to some extent. The sensitivity of color negative film is much smaller than that of black and white film. The negative color deviation is caused by the influence of color temperature and surrounding environment when shooting, but different color filters can be used to correct it in photo production. Color negative film is one of the most widely used color films.

Color reversal film can obtain the same color positive film as the subject after reversal processing. The color image, color reproduction and image clarity of color reversal film are better than those of color photos, and printing with color reversal film is better than that of color photos. Color reversal film, its color is true, bright and full. Strict requirements when shooting, small sensitivity and accurate exposure. If the exposure difference is 1/2 times, various colors, densities and layers will be obviously affected.