Microfilm was developed in the nineteenth century but was first produced in large amounts in the 1920s. In creating microfilm, a special camera takes pictures of pieces of art, each page of a book, or the pages of documents. These images are then reduced to 1/100th or smaller of their real size. The tiny images are printed onto reels or sheets of film and can then be viewed through microfilm readers, which magnify the images back to their original sizes. Today, many microfilm readers are connected to computers that can take PDF snapshots of the images, preserving them at the original size for use when away from the microfilm reader.
Microfilm is perhaps most often used to preserve newspapers, books and documents for scholars and historians, but there are a number of other uses as well. During the Franco-Prussian War and the First World War, spies used microfilm cameras to capture documents. The tiny images were then sent to headquarters using pigeons. The films were so light and small that it was easy for the birds to make long trips to deliver the information. In World War II, microfilm was used to photograph letters to and from the front. The film would be transmitted by air and the images were printed in their original size onto photo paper for the recipients to read.
Microfilm is literally a roll of film on a spool onto which images have been printed in miniature. The user loads the spool onto a device in the microfilm reader and scrolls the film forwards to find what she wants to read. Microfilm can be up to 100 feet long.
Microfiche, sometimes also called microfilm, consists of images printed onto an A6-size sheet of film. To read it, the user places it under a magnifier on a microform machine and clamps it into a square holder. The user then moves the square holder around to place the desired images under the magnifier.
Other microfilm forms that are no longer in wide use include aperture cards, which used a microfilm chip mounted into a cardboard card, and ultrafiche, which was essentially microfiche with denser images or larger amounts of data and microdots. Microdots were used most frequently in industrial or political espionage, and consist of a circular piece of film smaller than 1 millimeter in diameter. The dot is about the same size of the dot on an i or j in 12-point type.