Conservation DistList Archives [Date] [Subject] [Author] [SEARCH]

Subject: Microfilm resolution

Microfilm resolution

From: Peberdy Warwick <warwick.peberdy>
Date: Wednesday, August 4, 1999
Resolution Standard for Permanent Microfilm of Source Documents on
Flow Cameras

I have recently been asked by a commercial microfilming bureau to
review the Queensland State Archives' resolution requirements for
microfilm of permanent value source documents, in good condition,
that have been microfilmed on flow cameras. The Archives present
requirements for flow camera reductions of 24x and 40x are:

    5.0 resolution @ 24x reduction
    3.6 resolution @ 40x reduction

The reason for this request is that over the past few years many of
our agencies with in-house microfilming units have been forced to
close them down due to economic restraints. These agencies now use
commercial microfilming bureaus for microfilming their records.
While the Archives have always recommended that permanent records be
microfilmed on planetary cameras, some agencies have been using flow
cameras. This, again, is due to economic restraints. The cost of
microfilming on planetary cameras is roughly twice that of a flow

The resolution of flow camera microfilm has generally just been
meeting the standard 5.0 resolution at 24x reduction. The 3.6
resolution at 40x reduction is seldom achieved. A recent microfilm
of laser printed documents in good condition had a average
resolution reading of 3.2 at 24x which was rejected. At a subsequent
meeting with the microfilming bureau it was requested that Archives
review our resolution standards for source documents microfilmed on
flow cameras to:

    3.2 resolution  @ 24x reduction
    2.2 resolution  @ 40x reduction

These levels were stated by the bureau as being an industry standard
for minimum resolution and readability. They differ significantly
from the ISO standard. The bureau also stated that as flow cameras
cannot constantly achieve the ISO standard, agencies are being
forced out of microfilming and into digitising their records.

My question is: in an environment of economic rationalisation and
risk management, are our resolution requirements for microfilm of
source documents, in good condition, filmed on flow cameras too
high?  What are other archives in similar situations doing?

Warwick Peberdy
Manager, Preservation Services
Queensland State Archives
PO Box 1397
Runcorn QLD   4109
+61 7 3875 8704
Fax: +61 7 3875 8764

                  Conservation DistList Instance 13:12
                 Distributed: Wednesday, August 4, 1999
                       Message Id: cdl-13-12-016
Received on Wednesday, 4 August, 1999

[Search all CoOL documents]