In microform catalogue, entries are greatly reduced and printed upon a film or fiche. The microform cannot be read by naked eyes. A suitable microform reader, magnifies the reduced images on the film or fiche and projects them on to a screen is necessary for consulting a microform catalogue.
As mentioned earlier, microform catalogue may either be in the form of a microfilm or in the form of microfiche. Microfilm can be on a single reel, but generally it is housed (rolled) in a cassette containing two reels so that the film can be wound forwards or backwards within the container at the time of consultation. Microfilm readers usually allow the rotation of images through 90 degrees.
On the other 'hand, microfiche is a transparent card type format. A reduction of nearly 42 x 42 indicates that the width and height of the microimage is 1/40 of that of the original. Microimage area is correspondingly 1/1600 of that of the original would give 200 frames per card.
Microfiche has the advantage of direct access to a particular frame whereas microfilm requires a serial number through the film to locate a required entry, and serial search is a time consuming process compared to the direct access method afforded by microfiche. Microform catalogues are the output forms computerised cataloguing systems. These forms have been used extensively in the production of Iibrary catalogues since the early 1970s.
Some of the advantages of microform catalogues are:
Microform catalogues are compact and occupy less space in libraries. The space requirements of microform catalogues arise mainly because of space for microfilm or microfiche readers. They are portable and accessible to users depending upon the number of copies of catalogues and machines available. Multiple copies of these catalogues can be prepared easily and inexpensively. These catalogues are very easy to use and maintain.
The main disadvantage of microform catalogues is that they cannot be used without microform readers. They also require special care and protection. They are, in fact, useful only in very large libraries where massive data has to be stored and retrieved. They may not be that much useful in a medium or small library.