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Microfilming Techniques for Data Gathering and Field Research
Published online by Cambridge University Press: 10 November 2009
Extract
The foreign area specialist who goes into the field frequently finds it very difficult to acquire all the documentary materials he needs in the time available. Rare books, documents, and newspapers may be in libraries or in archival collections, but unless the writing is to be done in the field, it is difficult to use these sources. Furthermore, collections of papers, letters, clippings, pamphlets, and manuscripts are frequently available from private sources, political parities, and organizations, if one attempts to locate such collections, but they can rarely be borrowed, and certainly not for the length of time needed for thorough research. Similar difficulties may face the scholar engaged in domestic research. My answer to this problem has been to develop techniques for microfilming documents on location under adverse conditions using a minimum of equipment, which can be carried easily in a brief case. With a camera and a few other small items, it is quite easy and economical to microfilm materials and, if necessary, to process the films either at home or under very primitive field conditions.
- Type
- Notes de Recherche/Research Notes
- Information
- Canadian Journal of Political Science/Revue canadienne de science politique , Volume 3 , Issue 3 , September 1970 , pp. 476 - 482
- Copyright
- Copyright © Canadian Political Science Association (l'Association canadienne de science politique) and/et la Société québécoise de science politique 1970
References
1 The difference between ordinary film and microfilm can be illustrated by typical characteristic exposure-density curves shown in the graph in Figure 1. Note the much more narrow exposure latitude of microfilm and its higher contrast on the density scale. The resolving power of microfilm varies from approximately 135 lines per millimeter to over 500 lines per millimeter according to the type of film. By comparison, ordinary film has a resolving power of from 45 to 70 lines per millimeter, depending on the type of film and processing.
2 One should be aware that ASA speeds change slightly as exposure time is prolonged. There is no problem of variation in film speed if exposures are made between 1/10 sec. and 1 sec. Likewise, at short distances, there is a relative aperture change with the actual aperture being smaller than the indicated f-stop setting on the camera. This problem remains minor unless the camera is focussed at less than 2 feet. The change in f-value can be calculated with the following formula: Effective f-value = (Indicated f-value × lens-to-film in mm)/Focal length in mm.
3 The price of microfilm is about $7.00 to $8.00 per roll, although I have purchased some rolls for $4.00 overseas when the film was nearly outdated. At the list price, the cost averages about 1 cent per frame, or ¼ cent per page if four pages are photographed simultaneously. The cost of chemicals for processing will come to about ½ cent per frame, or less, depending on the number of rolls processed.
4 True archival permanence is achieved commercially with a hypoeliminator bath of hydrogen peroxide and ammonia solution. However, such a solution cannot be stored in a closed bottle because it creates a gas, so it is impractical for non-commercial use. The hypo clearing agent achieves approximately the same results and is easy to store and use.