Photo
Exposure metering
Correctly exposed black film can reproduce all grades of the grey scale. Colour negative films usually reproduce correctly six grades.
There are more problems with slides, the transparency films. Slide films can cover only four zones. However professional photographers put up with this drawback because slide has undeniable advantages. The colours are brighter and richer, the grain is much smaller than in negative films. Slide is more convenient for use in polygraphy. For example, you don’t have to guess what the colour of a sunset was in reality. It is even more important for reprinting of picture reproductions on paper and for other applied shooting where colour rendering is of great importance. But slides are extremely sensitive to exposure alternation. Even a 1/3 aperture ring shift from the center causes a considerable change of colour rendering. It’s extremely difficult to guess the slide colour before development of the film. That’s why experienced photographers make several takes with different exposures, and then they choose the best variant from a number of high-quality slides judging by their colour richness, correctness of colour rendering in light and shade of the picture.
Atypical subjects
Most subjects of shooting consist of a multitude of spots of different brightness. If you measure every spot and then determine the average brightness it’ll be in most cases close to middle-grey. That’s why automatic modes of exposure metering throughout the film aperture are so popular. Most modern cameras are supplied with such integral metering modes. They work precisely if you manage to bring the subject of shooting to the grey zone. But it may happen that an object doesn’t yield to integral exposure metering and demands individual approach. At a concert in a theatre only a small part of the shot will be lightened by the footlights; background may appear to be absolutely dark. In such case, integral metering will result in considerable overexposure.
Photographic equipment producers took account of it and supplied exposure meters with “spot” mode of exposure metering. In this mode the exposure meter taking angle is limited to 1-2 degrees. This allows selecting an object even against a hard background; you can reproduce this object as a middle-grey and use it for metering. This facilitates exposure metering at night shooting or at shooting against bright light. Even at shooting of a sunset when there is sun in the shot and integral metering can’t but fail, the “spot” pointed to the part of the sky which you want to become grey in the photo will show you absolutely correct exposure. Spot meter will make you feel sure in any situation.
8. An attempt to shoot such a picture relying on the camera automatics only will be a failure. You must apply corrections...
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