Microfilm technology

Image technology

• The storage of documents or other data that includes text, graphic, tables, and pictures
• 3 Image Technologies
• Facsimile
• transmits information
• Storage and retrieval of images, text, graphics and pictures
• Optical Disk
• Micrographics

Microforms

• Any medium that contains miniature or “micro” images
• Microrecords – records stored on microforms
• Micrographics – procedures for creating, using, and storing microrecords
• Types
• Roll film
• most economical and frequently used
• Microfiche
• fiche with reduction ratios of 90X or greater known as ultra fiche
• Jackets
• Aperture cards
• Nonstandard microforms
• Computer input microform

(Microfiche)

(Aperture card)

 (Microjacket)

(Microfilm)

Microform procedures and equipment
Each step in using micro-records requires special procedures and equipment:

• Filming
• Coding
• Processing
• Inspecting
• Duplicating
• Reading

Filming

• Document pre parathion
• Remove all paperclips and staples
• Mend torn papers
• Attach small papers to standard size paper with transparent tape or rubber cement
• Remove unnecessary attachments, e.g. envelopes, routing slips, duplicate copies
• Camera film
• Standard camera film uses silver halide emulsion to capture detail (often called silver film)
• Image size
• Reduction ratio compares film image size to original document size
• Reduction ratio of 24x = image 1/24th size of original document
• Image orientation = positioning of images
• Cine, comic, duplex, duo, duplex/duo
• Types of cameras
• Rotary (high volume)
• Planetary (flatbed)
• Step & Repeat (flatbed with overhead)
• COM Recorder (records electronic from computer optical machine to microform)

Coding

• Microforms during filming may be coded/indexed for automated retrieval
• Flash Targets
• Divides roll into information batches
• Bar Coding
• Requires additional equipment and space
• Odometer Indexing
• Indicates distance of each image from beginning of roll
• Blip Coding
• Predominant method
• Place rectangle beneath each image to identify; must be indexed

Processing

• 3 types of processing
• Deep tank
• Roller transport
• Straight film path
• Reversal processing
• Positive/Negative Polarity
• Developed for use with COM (computer output microform)
• 4 factors that affect developing
• Temperature of the developer
• Time film is in the solution
• Condition of the developer
• Agitation of film
• The higher the temperature of the developer, the less time the film is required to be in the solution

Inspecting

• Light box
• Density
• Numeric obtained through light background
• Resolution
• Sharpness of the image

Duplicating

• Duplicating process
• Types of copy film
• Silver Print
• easy to use
• expensive
• Diazo film
• Vesicular film
• cheaper
• consider using if not for long-term use

Advantages of microforms

• Floor space savings
• Fewer storage cabinets = reduced equipment costs
• Improved file integrity
• Images cannot be separated or misplaced like sheets of paper can
• Improved productivity
• Fast retrieval from automated systems
• Vital archival records protection
• Low-cost reproduction and duplication
• Admissible (in most cases) as evidence in court

Limitations

• User resistance
• Cost of purchasing and operating
• Turn-around time need to produce micro-images
• Original records inaccessible during preparation and filming
• Impractical for records that are frequently modified

Future of microforms

• Microfilm takes up about 2% as much space as equivalent paper records
• Permanence of from 100 to 500 years
• Can be read with human eye; not totally dependent on specific hardware/software for access
• Legality is well established