Microfilm is an analog storage medium using film reels which are exposed and developed into photographic records using a photographic process. It is typically used to store paper documents such as periodicals, legal documents, books and engineering drawings. It is compact in nature, is low cost to produce and store and requires far smaller storage space than paper documents. Therefore, it is considered to be a good archival form.
Viewing microfilm requires microfilm readers, which are simple devices consisting of a light source and magnification. Microfilm can be converted into an electronic format so as to be computer accessible. There are different types of microfilm, such as silver gelatin film, vesicular film and diazo film. Silver gelatin film is used for records which need to be kept permanently or for high-quality images. Vesicular film and diazo film are highly sensitive to high humidity or temperature. Microfilm is considered best for records which are accessed less frequently, but are still necessary to retain.
Advantages of Microfilm
- It enables libraries to greatly expand access to collections without putting rare, fragile, or valuable items at risk of theft or damage.
- It is compact, with far smaller storage costs than paper documents. Normally 98 document size pages fit on one fiche, reducing to about 0.25% original material. When compared to filing paper, microforms can reduce space storage requirements by up to 95%.
- It is cheaper to distribute than paper copy. Most microfiche services get a bulk discount on reproduction rights, and have lower reproduction and carriage costs than a comparable amount of printed paper.
- It is a stable archival form when properly processed and stored. Preservation standard microfilms use the silver halide process, creating silver images in hard gelatin emulsion on a polyester base. With appropriate storage conditions, this film has a life expectancy of 500 years. However, in tropical climates with high humidity, fungus eats the gelatin used to bind the silver halide. Thus, diazo-based systems with lower archival lives (20 years) which have polyester or epoxy surfaces are used.
- Since it is analog (an actual image of the original data), it is easy to view. Unlike digital media, the format requires no software to decode the data stored thereon. It is instantly comprehensible to persons literate in the written language; the only equipment that is needed is a simple magnifying glass. This eliminates the problem of software obsolescence.
- It is virtually impossible to mutilate. Users cannot tear pages from or deface microforms.
- It has low intrinsic value and does not attract thieves. Few heavily used microform collections suffer major losses due to theft.
- Prints from microfilm are accepted in legal proceedings as substitutes for original documents.
Disadvantages of Microfilm
- The principal disadvantage of microforms is that the image is (usually) too small to read with the naked eye and requires analog or digital magnification to be read.
- Reader machines used to view microform are often difficult to use; microfiche is very time consuming and microfilm requires users to carefully wind and rewind until they have arrived at the point where the data they are looking for are stored.
- Photographic illustrations reproduce poorly in microform format, with loss of clarity and halftones. The latest electronic digital viewer/scanners can scan in gray shade, which greatly increases the quality of photographs; but the inherent bi-tonal nature of microfilm limits its ability to convey much subtlety of tone.
- Reader-printers are not always available, limiting the user’s ability to make copies for their own purposes. Conventional photocopy machines cannot be used.
- Color microform is extremely expensive, thus discouraging most libraries supplying color films. Color photographic dyes also tend to degrade over the long term. This results in the loss of information, as color materials are usually photographed using black and white film. The lack of quality and color images in microfilm, when libraries were discarding paper originals, was a major impetus to Bill Blackbeard and other comic historians’ work to rescue and maintain original paper archives of color pages from the history of newspaper comics. Many non-comics color images were not targeted by these efforts and were lost.
- When stored in the highest-density drawers, it is easy to misfile a fiche, which is thereafter unavailable. As a result, some libraries store microfiche in a restricted area and retrieve it on demand. Some fiche services use lower-density drawers with labeled pockets for each card.
- Like all analog media formats, microfiche is lacking in features enjoyed by users of digital media. Analog copies degrade with each generation, while some digital copies have much higher copying fidelity. Digital data can also be indexed and searched easily.
- Reading microfilms on a machine for some time may cause headache and/or eyestrain.