What To Know About Your Microfilm
From the late ‘60s though early 90’s microfilm was a primary printing and storage tool for records management.
Paper was expensive to:
- Create
- Distribute
- Research
- Store
There are 3 formats of microfilm
Roll Film
Microfiche
Cards
Roll Film
a continuous length of film images in serial access order. Each roll contains related documents. Reels are 3 ½ “ in diameter.
16mm
100’ and 215’
Most common example of roll film
Can contain up to 5,000 images per roll
Used for all types of records
Source Document or COM
35mm
100’ lengths
Approximately 500 images per roll
Used for documents over 11” x 14”
16mm roll film
Standard film
Image Mark or
“Blipped film”
Dual Level
Blipped film
Duplex Filming
Film Cartridges
Continuous Forms
Microfiche
a flat sheet of film, 4” x 6”. Random access. Each fiche can be an individual file or part of a series.
Jacket
Channels are loaded with strips of 16mm film Updates may be added later
Can contain multiple files
Also available in 35mm version
COM
Computer Output Microfilm
May have up to 270 pages
Special forms
High density pages
Step & Repeat
Source document applications
Unitized, cannot update
High quality
Cards
for specialized uses.
Aperture Card
A frame of 35mm film mounted in a tab card. Typically an engineering application, many cards were produced prior to CAD. Cards may be punched with related data.
Microcard
An opaque card, usually 4 x 6, that contains source documents. No longer commonly used.
Originals
- The original or master is the silver based media created by filming the original paper document.
- To be the storage media and master for future duplication.
- The best version for scanning.
Duplicates
- Copy of original on Diazo or Vesicular film.
- The working copy, so the master can be stored.
- At least one generation removed from original.
- The stated reduction value is nominal
- Higher reduction decreases image quality
- Over 90% of film is in the 24 – 42x range
- A factor in 16mm and fiche, not the same scale for 35
