新闻摄影第三章（News photography third chapters）.docVIP

新闻摄影第三章（News photography third chapters） The third chapter is exposure control Exposure: from the object light through the camera lens, converging into image, fall in the emulsion layer of film, caused by the photochemical effect, generating the latent image, this is the photo sensitive, also called exposure. Developing, photochemical effect of silver halide is reduced to metallic silver. Without fixing, photochemical effect of silver halide is removed. Only the silver particles remaining on the silver film. Photographic film by flushing on photographic film after exposure to chemical treatment, the photosensitive film on the latent image into visible image. 1) black and white film: the process has development, stop display, fixing, washing and drying. 2) color negatives: similar with black and white. Only in the fixing add bleaching process, with the formation of silver image drift apart, leaving only the color image dye particles. 3) color reversal film: add black and white, color film than developing reversal processing processes 2. From the process requirements, color reversal film of the most complex process, the highest requirements; black and white film is relatively simple. Density: refers to the amount of silver particles accumulated in certain parts of the negative. If the accumulation of silver, this part became a black area, through which the light is very few, so this part is of high density part; if only a few silver accumulation is relatively transparent, so it is easy to light through, this part is called the thin part of film. This range is called the density range from the fully transparent low density part to the almost completely opaque high density part. It is this density range that produces all the image details. The film is too thick, but its too dense. Often overexposed or sometimes overexposed or overexposed. When printing, it takes a lot more exposure than a normal film to get a picture that looks normal. A scene, such as a different expos