Identifying your micro form images
Microfilm Reel or Roll Film 16mm/35mm
16mm Microfilm will often be in a small box (usually black) or in a hard case (often buff in colour), each 16mm reel can hold up to 2500 images, 16mm film holds original documents which were A3 or below, a master film will be grey/black in colour and a copy film will be deep blue which is commonly known as a diazo. Scanning the master film will always give you the best result, but both can be scanned. 35mm Microfilm will also be found in a black box with a flip lid it would have been used to film any image over A3 in size and again the master would be grey/black whilst the copy would be deep blue in colour.
Combination jackets/ Combination fiche
Combination jackets are made up of both A4 images (16mm) and over A3 images (35mm) and have one channel which holds the 35mm images and three channels which hold the 16mm images. They were most commonly used for planning applications, building control files and project files. Typically the combination jackets forms the first part of the file, whilst the remaining microfilmed images are housed in two channel (35mm) or five channel jackets (16mm) and will hold the 1 of 5, 2 of 5, 3 of 5 indicators – this was done to minimise the amount of jackets used to complete a full file. Once scanned in sequence your electronic images will mirror the original file.
Microfilm jackets / Microfiche 16mm/35mm
Microfilm jackets are generally 6 x 4 in size and contain microfilm images in rows, (known as channels) a 16mm jacket will have capacity for 5 rows and a 2 channel jacket which holds 35mm film will have two rows. Each jacket will have a strip across the top which will have been indexed by the original file/folder information – it may also say 1 of 3, 2 of 3 etc which indicates the size of the original file exceeded one jacket and was continued across a number in the same sequence as the original paper record.
The colours of the film will mirror that of roll film (see above) and again the better images are generally reproduced from the master.
It was also possible to microfilm in colour, and although rare this can be reproduced when scanning the original microfiche or film
Aperture cards are used for single drawings and are typically 6 inches in length. Each card will be indexed by the drawing number sometimes including the sheet number, revision number etc, however, some also have punch holes which indicate information relating to the drawing held on each card. These aperture cards can be scanned and indexed from either the card or the original drawing or plan contained on each.
Computer output microfilm (COM)
Computer output microfilm or COM was produced in the early days of computers, when storage space was expensive so information which needed to be retained was downloaded onto computer files and transferred to com fiche or com rolls each roll would hold circa 5000 images and each fiche 278 images.
Microfilm reader printers became expensive to buy or maintain and their availability has reduced significantly. The use of effective microfilm scanning services brings new life to archive microfilm records and removes the issues now associated with a microfilm legacy.
MICROFILM WILL DEGRADE OVER TIME
REQUIRES SIGNIFICANT SPACE TO STORE
HAS NO ABILITY TO SHARE THE INFORMATION
EQUIPMENT CAN BE DIFFICULT TO SOURCE AND MAINTAIN
LIMITED COMPLIANCE AND DISASTER RECOVERY
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