Microphotography in Archives -1

Introduction
   
Microphotography refers to the process by which documents, records, and other archival sources are photographed into a miniature or microscopic size. [1] They have many applications in science and industry, the most extensive being the microphotographic reproduction of documents. The advantages of the use of photographic reduction in recording documents are so obvious that it is not surprising that the first microphotograph was made shortly after the invention of photography.

    Microphotography for archives advocates the use of microfilm as a means of publication.   In microfilming images are reduced to such a small size that they cannot be read without optical assistance. This photographic compression leads to saving of space and is of enduring value. Microfilm has an estimated lifespan of 500+ years when stored in proper condition. Moreover, a roll of 35mm microfilm can hold about 900 pages and a roll of 16mm about 3000 pages.

    Today, Microphotography has developed into an important and widely used method of conserving documents in archives, as due to its small size, it is easy to store and access. [2]Archives, around the world, have started to incorporate the process of Microphotography in order to save on space as well as make the process of preservation easier.

    In this assignment, the development of Microphotography, the procedure encased, along with the benefits and hassles of Microphotography will be highlighted.

Background: Development of
Microphotography

    Archives were established as institutions that house documents, government orders, newspapers, and other primary sources. The word “Archives” is derived from the Greek word “Archion” which has been defined in the Oxford English Dictionary as ‘a place in which public records or other historical documents are kept.” [3]

    Archives are meant to house a collection of important records to help scholars, law makers, policy makers, etc. But, due to a humongous number of records, archives face a constant issue – lack of storage space.  Due to this, archives have sought out to adopt new techniques for storage like digitization of records.

    One such process that developed was Microphotography. The advantages of the use of photographic reduction in recording documents are so obvious that it is not surprising that the first microphotograph was made shortly after the invention of photography.

    Micro-writing and micro-printing were known centuries ago; indeed, the earliest specimens of micro-script have come down to us from the ancient Assyrians. The first photographic process was invented by J. N. Niepce in 1826. Niepce etched a metal plate on which there was a light-sensitive protective asphalt layer, but this method did not show great detail.

    In 1839, L. J. M. Daguerre was successful in producing the first photograph on an iodized silver plate developed with mercury vapour. This ‘Daguerrotype’ gave excellent quality, and when he heard of this new process, J. B. Dancer, in the same year, made the first microphotographs on Daguerrotype plates with a reduction of 160:1. In 1852, J. B. Dancer used the new collodion process to obtain the first transparent microphotograph.

     In 1887 H. Goodwin produced the first photographic film on celluloid base, and in 1889 T. A. Edison developed the 35 mm. cine film as it is still used today.

    Towards the end of the nineteenth century some libraries had already established photographic laboratories for full size copying work, but micro- film only came into use thirty years later. In 1924, the Leica camera came on the market, and it was essentially this camera which made it possible for the scholar to take his own microphotographs, and which stimulated microfilm activities. Nowadays, microphotographs are used in many libraries and, increasingly, libraries maintain their own photographic laboratories.

Procedure for Creating Microphotographs and the Materials Used

    A photographer who wishes to take a black-and-white photograph of a certain subject (e.g. a portrait or a landscape) normally uses in his camera a film which will give a negative. From this master negative he may produce paper prints at any time he desires. He may also decide to print this negative on transparent material (film or plate). When projected on a screen this trans- parent positive (slide) gives an excellent image. Although more light is needed for the projection, by reflection, of a paper print by means of an episcope, the image is less bright and lower in contrast and shows less detail than the image produced by a slide. [4]

    A microphotographic negative as used in documentary reproduction is produced on special material. Consecutive pages of a document may be photographed either in linear array on roll microfilm, taking one or two pages of the document placed on one frame or placed in a two- dimensional array on sheet microfilm. A first sequence of exposures constitutes the first line, the second sequence of an equal number of exposures makes up the second line, etc.     This can be achieved either by cutting microfilm into strips and mounting these strips one below the other, or by means of an automatic step-and-repeat camera, which works rather like a typewriter. The first line is taken by consecutive exposures, the sheet film carrier moving step-by-step in the direction of this line. When the first line is complete, the film carrier moves back into the position of the first exposure and at the same time one step down vertically. Now the film carrier is in position for the first exposure of the second line.

    When copies of a microphotographic negative are required, contact prints may be made either on transparent material or on paper. As in the case of pictorial photography, the projected image of the transparent copy may be expected to be brighter and of higher contrast, and it will, therefore, show more detail than the opaque copy on paper.

    On the other hand, paper is much cheaper than film, and micro-opaque prints are, therefore, of special interest for publication in microform. Micro opaque cards have another advantage in that they do not need a protective envelope and may be readily filed. However, they need a lot of light for projection and, therefore, a more complicated and more expensive reader, which must be equipped with a blower for cooling.

    Furthermore, the quality of the projected image is not as good as that of a transparent microphotograph, and there are certain difficulties involved when enlarged prints are required. Although it is possible to produce good microphotographs of very high reduction, a fundamental limitation of the reduction ratio for library applications arises from the mechanical tolerances of the microfilm equipment and from the difficulties of keeping the film flat enough. Very high reductions can only be obtained with microscope objectives on photographic plates of high resolution (e.g. Kodak Maximum Resolution Plates) using special focusing aids. This process would, however, be far too complicated and impractical for routine reproduction of documents, and similar difficulties would arise in connexion with reading equipment. [5]

    Practical limitations of the reduction ratio in microphotography of documents are imposed by the following considerations: (a) the quality of the original does not always allow for higher reductions (newspapers and the products of some office duplication processes are examples of low-quality documents) ; (b) the resolving power of the lenses of microfilm cameras and the microfilm material does not usually exceed 150-200 lines per millimetre over the whole field; (c) variations in exposure time and variations in processing conditions may occur in routine work, and have an effect on the quality of copying; (d) microphotographs used in libraries and documentation centres have often to serve as masters for further reproduction, and as each copying step involves a loss of detail a certain ‘reserve of resolution’ should be kept in hand.[6]

    When suitable equipment and material are used, when exposure times are fairly accurate, and when processing is done with care, microphotographs may be obtained in routine work which show a resolving power of 120-150 lines per millimetre. As the limit of visual resolution of a pattern in reading distance (about 30 cm. or 12 in.) lies between 5 and 10 lines per millimetre, reduction ratios of the order of magnitude of 15-30 diameters should give good microphotographs. In fact, most microphotographs for libraries are the result of a reduction of 10-25 times.


[1] Alfred Gunther, Microphotography in The Library, United Nations Educational, Scientific and Cultural Organization (UNESCO), Paris, 1962, p. 5.

[2] < http://egyankosh.ac.in/bitstream/123456789/11180/1/Unit-15.pdf >

[3] Dr. M. Sundararaj, A Manual of Archival Systems and The World of Archives, Siva Publications, Chennai, 1999, p. 5.

[4] Alfred Gunther; Op. cit, p.6.

[5] Alfred Gunther; Op. cit, p. 6-7.

[6] Alfred Gunther; Op. cit; p.7.