Micrographics The Basics

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Micrographics The Basics

• Susan L. Cisco, Ph.D., CRM, FAI
• Railroad Commission of Texas
• The University of Texas at Austin

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Agenda

• Explain fundamentals of a microfilm system
• Identify various photographic films used
• Describe effects of reduction ratios,
  magnification ratios, image orientation, image
  density, contrast, and resolution on image
  capture and display

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Agenda (continued)

• List use and benefits of various microforms
• Explain operation, components, and benefits of
  microfilm cameras
• Describe hardware and software used in film
  imaging and display
• Discuss preservation issues

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Microfilm An Overview

• Used for well over half a century
• Reduces storage requirements by 98
• Provides fast retrieval of high-quality document
  images with savings in labor and distribution
  costs

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Definitions

• Microform Generic term for any film-based
  information storage medium that contains
  photographically reduced images
• Micrographics Techniques associated with
  production, handling, and use of microforms, AKA
  film-based imaging

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Major Micrographic Applications

• Source document filming
• Computer output microfilm (COM)
• Micropublishing
• Library applications

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Micrographic Standards

• AIIM International (used to be National
  Micrographics Assn.)
• ANSI (American National Standards Institute
• ISO (International Standardization Organization)

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Reduction

• Reduction and magnification ratiossize of the
  film image compared to the original document.
• 24X is most common.

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Types of Microforms - Roll

• Roll filmmost economical and most frequently
  used, suitable for low-reference, long-term
  retention, sequentially ordered documents, as
  well as high-reference, randomly arranged
  documents that are retrieved by automated
  systems.

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Types of Microforms - Flat

• Flat film are sheets of film
• Microfiche
• Jackets
• Aperture cards
• COM (Computer Output Microfilm)

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Micrographics Advantages

• Reduced space, up to 98
• Legally acceptability
• Stable storage medium
• Increased employee productivity
• File integrity
• Easily duplicated
• Portability
• Reduced mailing costs

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Source Document Microfilming

• Conversion of paper documents to microform

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Types of Cameras in Source Document Microfilming

• Rotary
• Planetary
• Step and repeat

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Rotary Cameras

• Films high volume records. Film and document
  advance in the same direction and at the same
  speed within the camera.
• Filming speeddetermined by skill of the operator
  and condition of the documents.
• Film unitcontains film, shutter, and lens, which
  determines reduction ratio used.

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Rotary Camera Components

• Lighting controls
• Automatic feed mechanisms
• Receiving trays and stackers
• Check endorser
• Sequential numbering device
• Image-count device

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Planetary Cameras

• Used primarily to film engineering drawings and
  other large documents, AKA flatbed cameras.
• Film and document remain still during exposure.
  Document to be filmed is laid flat on camera
  table (copy board). Amount of light required is
  registered through a light meter and light
  intensity is adjusted.

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Other Flatbed Cameras

• Small-document planetary camera (table model
  planetary)miniature version of large engineering
  planetary camera. Films documents that cannot be
  satisfactorily microfilmed on rotary cameras.
  Also used for microfilm jacket work and
  microfiche work.

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Step and Repeat Cameras

• Produces microfiche. Images are exposed in
  uniform rows and columns on a sheet of 105mm
  film.
• Updateable microfiche cameraalso a
  step-and-repeat camera which used to produce
  updateable microfiche. No longer manufactured.

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COM (Computer Output Microfilm)

• Captures electronic data from the computer on
  microfilm without paper intermediary, usually in
  the form of microfiche.

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Measures of Image Quality

• Resolution Measure of the sharpness of the
  characters of the image on film.
• Density Measure of the amount of light
  transmitted through black background, AKA
  background density.

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Film Technology

• Silver halide film. Produces images of negative
  polarity. Common film widths are 16mm, 35mm, and
  105mm. Packaged in 100- and 200-ft. rolls. Dry
  silver film has no wet chemistry used in its
  processing (development).

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Film Technology

• Copy filmused to make duplicates of the
  processed camera films.
• Diazo filmnon-silver film used exclusively for
  contact printing. The latent image is developed
  by exposing the diazo film to ammonia vapors in a
  development chamber of the duplicating machine.
• Vesicular filmdeveloped by a heat process. It
  is a reversal film a positive original produces
  a negative vesicular copy. Not as effective as
  diazo or silver.

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Film Technology

• Copy film (continued)
• Silver print filmtwo types one is a reversal
  film which produces positive copy from a negative
  original or vice versa. The other type is a
  non-reversal film

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Film Processing

• Processormachine used to develop microfilm.
  Three types of processors deep tank, roller
  transport, and straight film path processors.
• Development factors include temperature of the
  developer, length of time film is in the
  solution, condition of the developer, and the
  agitation of the film.

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Readers

• Must have excellent illumination system, good
  optics, and provide fast access to the image.
  Types of readers
• Roll-film readers
• Cartridge readers
• Cassette readers
• Microfiche readers
• Aperture card readers
• Multiformat readers

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Reader Printers

• Can provide electrostatic plain paper prints of
  the image displayed on the screen.
• Prices range from 4,500 to 33,000.

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Computer-Assisted Retrieval (CAR)

• Equipment that uses potential of computer to
  allow filming in random order with fast, precise
  retrieval.

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Preservation Issues

• Separate silver and non-silver microforms
• Storage containers need to be acid-free and
  corrosion-resistant
• Rubber bands are unacceptable
• Use non-acidic paper wraps