Microform

Microform is the generic term for reduced on film analog images of printed materials as well as directly written onto the medium of digital information such as a printer ( Computer Output Microfilm ( COM)). The main microforms are microfiche ( Microfiche ) and microfilm on spools or in cartridges ( roll film ). The most common is microfiche, size 105 mm × 148 mm (DIN A 6), 16 -mm and 35 -mm microfilm on reels. A special form is the film card, a punch card, in which on the left or right side of a window die cut, into which a 35 mm microfilm image is adhered.

Areas of application

Microforms are mainly used for archiving. One reason for the film adaptation is the relatively long shelf life and technological independence of the media. Many long to be stored, threatened by decay, but also particularly valuable documents / publications are therefore made ​​into a film; parallel can also be made digitization. One speaks in this case of " Hybrid archiving". Microfilms are read with microfilm readers and by Lese-/Rückvergrößerungsgeräten also reproductions can be made in addition to reading.

Until the advent of powerful digital-only audit-proof archiving systems for mass data GST archiving of transactions took place (eg, copies of billing ) predominantly via digital COM filming on microfiche.

With the European Register of Microform Masters ( EROMM ) there exists an international database that serves as a detector of works that have already been filmed or their filming is imminent.

In addition to archiving you pulled up to the wide availability of suitable storage media for computers also benefits from the low space requirement and the possibility of duplication. Larger information systems, for example, for telephone subscriber, catalog orders and travel arrangements based on this method. Even extensive technical documentation has been in the automotive industry, for example, stored on microforms and reproduced for stores / shops.

History

The microfilm was invented by René Dagron in 1859 in Paris. At the siege of Paris during the Franco-German war in the years 1870/71 he helped to improve communication between unoccupied France and the capital.

Technology

The properties of microforms are defined in different DIN, EN and ISO standards.

The microfilm base is usually made of polyester ( polyethylene terephthalate), formerly acetate was used. The light-sensitive coating is composed of a silver halide emulsion ( silver film ) or a compound of diazonium salts ( diazo ). In general, the higher quality of silver film (Master - film ) are made deductions on diazo film. Standardized reduction factors for 16- mm microfilm are 1:20, 1:24, 1:32, 1:40, 1:42, 1:48 and 1:96; for 35 mm microfilm 1:7.5, 1:10,5, 1:14,8, 1:21, 1:29,7.

Although the monochrome film is the most common form, there are also color microfilm, which is produced only by Ilford as " Ilfochrome Micrographic " world, and of color films is very different.

The durability of microfilm is stored respectively (21 ° C, 50% relative humidity) are up to 500 years. We Also is the slogan of a microfilm company "Digital for now, analogue forever" - something like: "Digital for the moment, analogue for eternity ," or " digital storage, archiving analog".

Laser exposure

A Renaissance learns of microfilm in the digital age by the possibility of laser exposure. In the laser exposure of red, green and blue lasers can be modulated according to the color channels of the digital RGB files and focused to a "white" beam. Colors can thus very precisely and exactly, pixel for pixel to be written to a movie.

Digital data on microfilm

There is also the possibility of digital data to be archived microfilm. However, the achievable data density is low, there is also the danger of obsolescence digital.

Special applications

• Numerous cultural and historical documents on microform are for long-term archiving in Barbarastollen in the Black Forest.
• In the microfilm archives of the German-language press in Dortmund numerous newspapers are archived.
• The Central Library in Zurich archived several newspapers on microfilm. The archive goes back to the first edition of the Neue Zürcher Zeitung.