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Subject: Microfilming

Microfilming

From: Gary Saretzky <saretzky>
Date: Monday, August 3, 1998
Re the question of whether 16 mm microfilming can be used for
materials 11x17 or smaller: It depends on the the intended purpose
of the film and the characteristics of the material to be filmed.

The standard for preservation microfilm--film for records that are
to be retained indefinitely--is still 35mm.   If a grant is used to
help pay for filming, it will likely require 35mm.  The larger film
size allows filming at lower reduction ratios; thus, less
enlargement is needed to view the image.  The sharpness and clarity
of 35mm is almost always going to be better than 16mm.  Since 35mm
film is used in planetary cameras, it is easier to make adjustments
for individual images during filming.  If the film is ever
scratched, less of the information is lost than film shot at high
reduction rations.

16mm film has a lot of appeal for cost reasons and also if
microfiche is needed as a final product.  16mm cameras often can
take two rolls of film simultaneously, eliminating the time needed
to duplicate the master, and these rolls can be processed
simultaneously as well. Some 16mm cameras are rotary cameras,
allowing the operator to feed stacks of paper into the machine, if
they are of uniform size.  For modern typewritten material, 16mm
film is adequate for most reference purposes.

For either 16mm or 35mm film, the Resolving Power should be 120 or
higher.  Resolving Power is calculated by multiplying the Reduction
Ratio by the Resolution Pattern. (For more information about this,
see the book Preservation Microfilming, 2nd ed., by Lisa L. Fox, ed.
[1996].)  One reason Resolving Power is important is that it affects
the accuracy of scanning, if conversion to an electronic format is
ever needed; it is more economical to scan good film than original
paper documents.

Gary D. Saretzky
Coordinator, Public History Internship Program Rutgers University;
Archivist, Monmouth County, New Jersey; Chair, NJ Caucus,
Mid-Atlantic Regional Archives Conference

                                  ***
                  Conservation DistList Instance 12:15
                 Distributed: Wednesday, August 5, 1998
                       Message Id: cdl-12-15-003
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Received on Monday, 3 August, 1998

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