Filters [antikvár]

The need for filters Filters are the most often used, and at the same time misunderstood, of all optical accessories. In the early days of photography, filters were needed mainly to correct the deficiencies and limitations in the spectral response of then available photographic emulsions. These films were generally deficient in their sensitivity to the red end of the spectrum, rendering these colours dark in comparison with green and blue. Nowadays, filters are used with black-and-white films to manipulate the effect of certain areas in the subject, either by darkening or lightening other tones in the picture, or by increasing the contrast between similar colours. With colour film, the use of a suitable colour filter prevents noticeable and unnatural colour casts when the film is exposed under light of a colour different from that for which the film is balanced. More recently, filters are being used to deliberately distort the recorded colours for pictorial effect; they now provide the photographer with a valuable tool for creative self-expression. 1 Skilled photographers have learned by study or controlled experiment how filters work, and their effects on colours and materials. But with the rising cost of films and, more important, the risk of losing a never-to-be-repeated subject, this book aims at providing a working knowledge of filters, an understanding of their effect, and a guide to their use that will improve the pictorial standard of its readers' photographs. Modern films are the result of more than a century of research and experiment; never before has the photographer had available materials capable of recording everything in full colour or representative tones of grey so faithfully. Modern emulsion chemistry is so advanced that very small quantities of the ingredients can be mixed to tailor the precise characteristics of the photosensitive material, and