Aperture cards are an affordable way of storing or archiving multiple copies of documents, engineering drawings and maps, and photographs to ease access, distribution, and long-term storage.

1. What are Aperture Cards and their types, How are they used?
Aperture cards are an affordable way of storing or archiving multiple copies of
documents, engineering drawings and maps , and photographs to ease access,
distribution, and long-term storage.
Aperture cards were introduced in 1943 and used by US military agencies to
capture and archive photographs of strategic value and other important documents.
An aperture card is basically a holerith card with a cut-out window where a chip of
16mm or 35mm microfilm is mounted.
This microfilm mounted consists of an optically reduced image of a confidential
document such as an engineering drawing, maps or newspaper pages. The aperture
card can be viewed only on a specialized card reader which interprets the metadata
on the punch cars and enlarges the film for easy viewing.
The use of microfilm has been widely popular for archival purposes as well as a
solution to bulky, expensive storage of print materials. Over the years, improved
film, better readers and viewers, high-tech reader-printers, and portable readers also
helped drive the popularity of microfilm storage options. Today, though microforms
are still used to preserve and store documents, businesses are opting to scan and
digitize their microfilm and microfiche cards. This allows content to be easily viewed
on computers and shared and stored digitally.
Different Types of Aperture Cards Available
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Conventional aperture cards – A conventional aperture card (82.5mm x
187mm) have a microfilm mounted on a window provided on the card with
dimensions of approximately 50mm x 40mm that will light to fall on the
microfilm image, allowing the data contained in it to be read.
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Duplicards – These are aperture cards with duplicating film pre-mounted in
them, but unexposed. Of dimension 82.5mm x 187mm, the duplicard consists
of a diazo emulsion microfilm and is used for making a copy of an original
aperture card for future use.

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Camera cards – They are similar to and of the same size as conventional
aperture cards and duplicards. Unlike a duplicard that has a piece of
unexposed microfilm pre-mounted on the card, a camera card has a piece of
unexposed silver halide microfilm pre-mounted on it. Camera cards are used
in special type of cameras that can capture voluminous data such as large
maps and engineering drawings.
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Polyester Pocket Aperture Cards – These cards feature a polyester
pocket placed in the card on which microfilm is mounted. They do not
use adhesive tape like duplicards. The most popular type of polyester
pocket aperture card now in use is the MIL-D card.
Advantages of Aperture Cards
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With a life expectancy of 500 years when appropriately processes, they offer
stable document storage
Actual images are stored, so there no need of any software to access or
decode them
Stored pages cannot be torn or destroyed as with paper
Save storage space by 95% compared to paper documents
Are easier and cheaper to distribute than paper documents
Prints accepted in legal proceedings in lieu of original documents
Prevents editing of images stored in them
Rare and fragile documents can be stored and accessed while avoiding risk of
damage or theft. This is of great use to libraries and government
organizations
For Conversion to Digital Format
When the Internet took over as the main medium of communication worldwide, and
digital storage systems became widespread, businesses and public and private
organizations began scanning aperture cards to digital formats such as JPEG, GIF, TIFF
and PDF. A professional document scanning company would have all the resources
necessary to address high volume conversion of information in aperture cards to digital
format efficiently and affordably.
With businesses and other organizations adopting digital systems for archiving and
sharing of important documents, the need for aperture cards was reduced. However,
aperture cards have their own advantages and disadvantages when compared to
digital systems, and still play a significant role in helping business with archiving
certain types of documents.