How to classify and use photographic paper in black and white photography

There are two kinds of photosensitive materials: photosensitive film and photographic paper. There are many kinds of black and white photosensitive materials, which can be roughly divided into three categories: silver halide system, unconventional silver halide system and non-silver halide system. This paper introduces a photographic black-and-white photosensitive material based on silver halide system. Specifically, it is black and white film and black and white photographic paper. The film thickness is only a few tenths of a millimeter, and the main components are film base and emulsion, while the main components of photographic paper are paper base and emulsion. Classification of black and white photosensitive materials: 1. Types of photographic films. Classification by morphology-hard film and soft film, also known as dry film, are based on glass, which has been basically eliminated because of its bulkiness and fragility. The film base is cellulose triacetate, cellulose acetate or polyester, which is relatively light. There are two kinds of film: page film and roll film. 4~ 12 inch pages have many specifications, and the volume specifications are many. For example, the domestic common models are: 120 (width 6 1mm, length 8 15mm, 60mx90mm812, 60mx90mm8,60mx70mm). 135(24mm x 36mm36 sheets) There are also 220, 1 10, 126 models abroad. (1) color-blind film only feels blue and purple short-wave light, and the film has low photosensitive speed, poor color sensitivity, small tolerance, fine silver particles, high resolution and large contrast. (2) spectral sensitizer (red pigment) is added to the color separation (positive film) emulsion, which can feel blue-violet light and yellow-green light, but not red-orange light, and is suitable for shooting scenery films and scenes without red. All aspects of performance are between color-blind film and panchromatic film, which are mostly used for printing and plate making. ⑶ A spectral sensitizer green pigment which can feel yellow, green and red light is added to the full-color emulsion, and all colors of light can be felt. Almost all products sold in the market are full-color films. The film has high speed, wide tolerance, good color sense, thick silver grains, low resolution and flat contrast. (Feel all kinds of colors of light, used for scenery, portraits, news and flower shooting) 13. Film for recording invisible light images (1) Infrared film feels invisible light in the infrared region, so a crimson filter must be added to filter out blue light and ultraviolet light. Treat as ordinary black and white photographic film. (2) Special photosensitive material for UV film, timely glass lens and UV filter. ⑶x-rays are used to shoot three kinds of films that record invisible light waves. The wavelength of invisible light waves is shorter than ultraviolet rays and longer than gamma rays. They are mainly used for scientific research, criminal investigation and medical treatment. 3. Film classified by sensitivity (1) Slow film (2) Medium film (3) Fast film (4) Fast film (5) Multi-speed film (5) Common special photosensitive film (1) Black and white dye film (2) Polaroid one-step imaging photosensitive film (3) Black and white photosensitive material for microbubble film:/. Movie selection 1. The selection of photosensitive materials is mainly considered from three aspects: specifications, types and film speed. Specification: 135 membrane (24*36mm), 120 membrane (6*6, 6*7, 6*9mm), 1 10 membrane (13 */kloc-) Color negative who takes color photos or makes light box film; Selection of film speed: the principle is that it should be low (speed) rather than high (speed) (high times). Storage conditions: black and white film below 20℃, color film 10℃ (refrigerator). 2. Identification of photosensitive materials. Identification of black and white film, color negative film and color reversal film. On the outer packaging or cassette of black and white film, such as plus-pan/tri-xpan/NEOPAN. Black-and-white photographs, etc. For example: Le Kai black-and-white film: Lucky Pan /shd 100/ Black-and-white film135-36 color negative logo: color such as Kodak color/Fuji color/color film/film, etc. For example, Fuji color film Super HR 100/ color negative/Daylight /ISO 100/2 1. /24X36mm/135-36EXP Another: fujifilm /Superia/ Film used for color printing Le Kai color film: used for printing and playing color photos/lucky colors/sunlight /ISO 100/2 1. Process c-41/24x36mm/36EXP (New Le Kai) Super Gold 100:36 exp/ Sunlight/PROCESS C-4 1 Color reversal film is marked as: chromium such as Kodak Chrome/Ektachrome/ color slide film, etc. 1. Discrimination between professional films and non-professional films 1. Identification of professional solar films and optical films: identification of solar films: tungsten 2. The choice of paper and photographic paper should be considered according to the condition of the film and the purpose of the photo. For example, the contrast of negative film is small-the contrast of negative film of hard magnifying paper is large-the plate-making printing of soft magnifying paper with small number of papers-choose large glossy paper and plastic-coated paper to watch-choose silk grain and textured paper (the negative film is defective or the particles are coarse).