Academics and experts
like to refer to the technology of creating small images on various types of
film as "micrographics" and reserve the term "microfilm" for roll film. At
least 90% of the general public have no idea of the meaning of
"micrographics" but they do know a little about microfilm - which goes to
show how far removed academics and experts can be from real life! G G
Baker & Associates have been involved with microfilm since the consultancy
was founded in 1968, a time when there were only two options for document
management - paper or microfilm. We were microfilm consultants long before
some librarian coined the term "micrographics" and favour the use of the
term microfilm in a generic sense to cover all formats.
Over the years we
have witnessed the rapid adoption of digital systems for active files and
fully accept that electronic document management is far superior to
microfilm for most live documents, but a case can still be made
for microfilm as a long-term storage medium until some form of digital
storage has been developed with an equivalent archival life and sufficient
standardisation to ensure that records entrusted to it will still be fully
for 100 or more years.
This chapter has been prepared for those who
are unfamiliar with modern microfilm methods, those who are inclined to
regard micrographics as an outdated technology but are willing to
investigate its merits, and those who appreciate its advantages but
associate it with smelly chemicals.
Chemicals are still required for some types of film
development and duplication, but there are alternatives for those who wish
to conduct operations in-house. However, the trend today is toward
outsourcing of services and a large number of bureaux in the UK cater for
all aspects of filming and duplication - users only handle dry, processed
film. Some systems combine both methods of production, with urgent or highly
confidential work being handled by a single in-house camera while bulk
conversion of paper to film is entrusted to a local bureau.
To understand the technology it is necessary to know that
microfilm comes in several formats. Each is designed for a specific purpose
and every aspect is fully covered by standards - many of which we helped to
prepare when G G Baker Chaired the British and International committees
responsible for micrographic standards. The microformats in current use
Roll microfilm is either 16mm or
35mm wide (105mm roll is also used during the production of microfiche, but
it is cut into individual A6 size sheets before use).
Unlike cine film, roll microfilm is not perforated and
only a small margin at the edges is required to enable it to be held in a
camera and subsequently in a microfilm reader or scanner. Almost the entire
width is therefore available for recording images which are usually arranged
in a single row along the length of the film although two alternative
layouts are permitted. Both of the alternative options result in a double
row of images. In duplex format the fronts and backs of all documents are
recorded side by side across the film width. In duo format the documents run
sequentially along the top row and then back down the lower row; this is
achieved by filming one track, reversing the film in the camera and then
recording the other track.
16mm roll film is ideal for recording most office
documentation but a larger image is desirable for recording fine detail of
large originals such as maps, plans, newspapers and engineering drawings.
35mm film is generally used for such applications either in roll form or as
individual images set into aperture cards which are described later.
Circlips are often used to permit the easy identification,
handling and loading of roll film on
reels. They provide dust protection, a flat surface for labelling and
they facilitate rapid threading of film into a reader or reader-printer. They are
almost universally employed with automated image retrieval systems based on
roll formats and the design of the circlip has been standardised to permit
films to be exchanged between equipment from different sources.
Before the introduction of the standardised circlip (also known as a
C-Clip), two types of cartridge were in use. Although the film itself was
standardised, the cartridges were not interchangeable. Roll film
readers and reader-printers are, therefore, often available with alternative
film carriers for C-type, Kodak or 3M type cartridges.
Image retrieval from 16mm roll film frequently relies on
counting small marks filmed below the images. Very rapid search times are
possible within any specific roll, but the rolls usually have to be loaded
or interchanged manually and this increases the total time required to
locate a set of images held on different rolls.
are sheets of film, They are usually A6 in size but an A5 sized alternative
was popular for certain applications including automotive parts catalogues.
Microfiche contain images set in a
grid pattern in regular rows and columns. An eye-legible title along the top
of the microfiche permits instant identification without the need for
magnification. Standard microfiche are produced to strictly controlled
layouts which permit the retrieval of any image via a co-ordinate
representing the intersection of the row and column where it is located. At
least one index frame is usually included on the microfiche to provide
access to its content without the need for an external index. Fiche
conforming to ISO and BS Standards thus contain sets of images and integral
indexing, enabling them to be duplicated and distributed as required. The
images can be recorded from paper originals using special step-and-repeat
cameras but these days they are often produced from digital input via the COM (Computer
Output on Microfilm) process.
similar in appearance to the microfiche, but differing in its area of
application, the microfilm jacket comprises rows of images cut from roll
film and held in a carrier which is usually A6 in size. Each jacket consists
of two sheets of thin clear plastic cemented or welded together at intervals
to produce channels into which strips, or even single frames, of 16 or 35mm
roll film can be inserted. Because additional frames can be added at any
time the system was particularly suitable for files such as customer records
- a separate jacket being allocated to each customer. Combined jackets,
holding both 16mm and 35mm widths are also available. The maintenance of
jacket systems is labour-intensive and they are not widely used today.
Aperture cards have already been mentioned as
a popular microform for handling large originals such as maps and plans. The
concept of a single film image set into a “window” cut into a card carrier
dates from around 1934, but it came into practical use during the Second
World War and was widely adopted for engineering drawing applications after
the format was subsequently standardised by the US Department of Defence.
The dimensions of current aperture cards are 187.25 X 82.5mm because during
the 1970’s Hollerith punched cards of that size were commonly used for data
input to computer systems. The mechanical sorters used for computer
applications were adapted for sorting the aperture cards. It is still
possible to punch the body of the card to record data such as the drawing
number and original drawing size and to sort the cards mechanically on
special card sorters. Some aperture card printers can interpret data punched
or marked on each card and use it to determine the number and size of prints
required. Similarly, automated card duplicators can read data on master
cards and use it to produce the correct number of copy cards.
There are 2 basic formats of aperture card for camera film:-
M1 Aperture Cards
For ease of identification, if you look at the aperture card with the cut
corner in the top left, then an M1 card will have the adhesive tape on the
rear of the card and the hole (or aperture) will be to the left of the card.
When a frame of 35mm microfilm is positioned on to the adhesive tape, the
emulsion side of the film will be at the front of the card. (Dimensions for
this card are 187mm x 82.5mm)
M4 Aperture Cards
With the cut
corner in the top left, then an M4 card will have the adhesive tape on the
front of the card and the hole (or aperture) will be to the right of the
card. When a frame of 35mm microfilm is positioned on to the adhesive tape,
the emulsion side of the film will be at the rear of the card.
Similarly - there are two types of Copy card for duplicating, supplied
ready-fitted with diazo film in the aperture.
To ensure correct duplication, With the cut corner to the left the
aperture and the film will be to the left with the adhesive and film on the
front of the card.
With the cut edge to the left, these have the adhesive and film on the back
and the aperture will be to the right.
The standard colour for aperture cards is buff and copy cards
are normally salmon but a range of other colours is available.
From time to time other micrographic formats
have been proposed, often involving very high reduction ratios. None has
survived long enough to become an adopted standard and potential users are
well advised to employ only those products which strictly conform to the BS
and ISO standards that have been established to control quality and layout.
This ensures the widest possible choice of sources of supply and total
compatibility with other systems anywhere in the world.
This site contains specifications
for virtually all of the micrographic hardware currently being marketed in
the UK. Equipment is listed under sixteen headings covering cameras used to
film documents, processors to develop the exposed film, duplicators to
create copies, COM recorders to generate film from digital input, scanners
to digitise microfilm images, splicers for joining film and adding leaders,
readers for viewing film, reader-printers for reading and printout when
required, quality control equipment including densitometers and sundry items
required for production including inspection stations, winders and cartridge
Planetary, or flat-bed cameras
are used for applications where the highest possible quality is required.
Because both the document and the film are stationary during exposure it is
possible to achieve maximum image resolution on the film. Other advantages
include the provision of infinitely variable reduction ratios by altering
the distance between the camera and the document. The main disadvantage is
that the process tends to be much slower than rotary filming. Automatic document
feeders are available for a few planetary cameras, but documents are
normally positioned, filmed, and then removed by hand.
Some retrieval systems require up to three blip sizes beneath the images.
Another common requirement is numbering and/or dating each image. Suitable
facilities are often available for planetary cameras as optional extras.
Many planetary cameras are
designed for engineering drawing applications which may involve the filming
of translucent originals. These often require a sub-surface illuminator
comprising a glass platen with lights below it.
Library applications involving rare and delicate books frequently demand the
use of a book cradle to gently support the open book and bring facing pages
into the same focal plane - these may be offered as optional extras.
Some compact planetary cameras are designed exclusively for 16mm roll, in
which case there may be provision for two rolls to be exposed
simultaneously, thus creating an archival copy and a working copy. Larger
roll film planetary cameras are usually able to accept both 35mm and 16mm
film. Several models are offered with a range of interchangeable camera
heads to permit the production of 16 and 35mm roll, processed aperture cards
and also master microfiche by step and repeat filming.
Automation has been applied to lighting and focus adjustment, the processing
and titling of aperture cards, frame numbering, the addition of image
count blips to roll film and the creation of eye-legible titles on
microfiche. Microfiche camera heads must also incorporate a means of
altering the image grid format and this may be either mechanical or
electronic. All options can not always be combined on one camera.
Planetary cameras can sometimes be linked to a computer system to permit the
film address of each image to be input to an index held on the computer.
Much of the data can be generated automatically; for example the frame
number will increase by one for each exposure. Other data may be manually
entered from a keyboard or extracted from bar-code headings on the
Aperture card cameras usually deliver fully developed, fixed and washed
aperture cards. Options include image verification on a screen as the card
leaves the camera, automated punching of the cards, and the printing of
indexing and titling information on each card. Other facilities may include
the automatic compilation of job records with details of the size and
orientation of each image generated.
Maximum resolution is not usually constant throughout the full range of
reductions, but most planetary cameras can record at a minimum of 125 lines
per mm. Some cameras feature automatic control of image density so that
varied input produces identical images. This greatly simplifies subsequent
operations such as duplication and printout.
Rotary filming is considerably
faster than planetary filming because it is performed as a continuous
operation, most rotary cameras
have an automatic document feeder. Pages are filmed as they pass through the
camera and the relative speeds of the film and documents are carefully
synchronised to maintain good image resolution.
The reduction ratio is usually determined by the camera unit.
Interchangeable camera units may be available to provide a range of ratios
and also permit each department of an organisation to have its own dedicated
camera unit. Widely available options include the ability to film both the
front and back of each document, presenting the images side by side across
the width of the film in "duplex" format. Alternatively, documents can be
filmed along one half of the film width and then back along the other half
in "duo" format.
Because the filming process is continuous, there may be no restriction on
the length of the input, but its maximum width is limited by the size of the
camera throat. The maximum width that can be recorded on film is a little
less than the maximum sheet width.
Indexing and retrieval methods for which standard or optional facilities may
be offered include one, two or three level blip coding of the images and
Some rotary cameras can stamp and endorse each page as it is filmed to
record a unique number, the date of filming or other information for
checking, indexing or retrieval. The more sophisticated units can read
bar-code patches on the documents and automatically compile an index. It may
also be possible for the camera to be programmed for several common job
set-ups to save time on repetitive filming operations. Cameras
combining high-speed, high-resolution electronic scanning and simultaneous
microfilming are available to produce an archival file while inputting
documents to an electronic image processing system, these are known as
Most silver halide microfilm cameras only expose film. Before it can be read or
duplicated, it must be developed, fixed, washed and dried using a
film processor. Silver film
processing can sometimes be undertaken in daylight but a darkroom is
required for most applications. Some cameras, COM recorders and CAD
plotters incorporate their own processors and deliver film ready for use,
some use alternative types of film.
Conventional silver halide film processing transports the exposed film
through liquid developer to convert the silver halide grains that have been
exposed to light to metallic silver. This conversion is sensitive to time
and temperature. Strict control of both the heat of the chemicals and the
speed of the passage of the film through them is necessary for consistent
results. A rinse may follow to remove any surplus developer; a stop-bath
also helps to avoid staining and streaking of the film and prolongs the
working life of the fixing solution. The next stage is fixing in a solution
usually composed of sodium or ammonium thiosulphate, which dissolves all
undeveloped silver salt. The film is then thoroughly washed to remove
residual developer and dried before being wound on to reels, delivered as
cut fiche or mounted in aperture cards.
Conventional processing produces a negative image with clear print on a
black background. Areas of the film emulsion that have been sensitised by
light turn to black silver and the parts which did not receive light (the
print on a page for example) are washed away leaving virtually clear film.
COM recording, which uses a CRT or laser to expose the film, creates text,
lines and patterns by using light, so conventionally processed silver halide
COM film is positive with dark print on a clear background. If negative
output is required, a slightly more complex processing sequence can reverse
the polarity of the images. The sequence for full reversal processing is
first development, first wash, bleach, clear, re-expose to light, second
development, fix, wash and dry. It will be seen that a processor with six or
preferably seven tanks is desirable for full reversal processing.
Water consumption and the disposal of waste water and chemicals are points
to consider when contemplating in-house processing. The alternative is to
send films to a local bureau or film laboratory for developing, fixing and
Silver can be harvested from used processing solutions using electrolysis.
Advantages include the prevention of excessive sulphite destruction as well
as the intrinsic value of the material recovered. Some bureaux offer
facilities for collecting waste chemicals, extracting the silver and safely
disposing of the residue.
Diazo, silver halide and vesicular films are all used for the production of
copies from microforms. Each has advantages and limitations, but most
document based applications now use diazo material for duplication. The
characteristics of the three methods available are outlined below.
Diazo material is sensitive to ultra-violet light but can be handled in
daylight. It is exposed by placing it in close contact with a master film
and projecting UV light through the master on to the copy film. Areas masked
by dark parts of the master are protected from light while those in contact
with clear parts of the master are sensitised.
To develop the diazo film it is passed through ammonia vapour which causes
diazonium salts in the coating of the copy film to couple with other
chemicals and form organic dyes in the areas unexposed to UV light. Where UV
light has reached the copy film the salts are rendered inert and no dye is
formed. Diazo is thus a non-reversing medium and a master negative will
produce a negative diazo duplicate.
Diazo duplication can be performed in daylight because small quantities of
UV light do not affect the film. Unless the duplicator has an internal
filtering system, or only moderate volumes of duplicates are produced, it
may be necessary to arrange for exhausted ammonia fumes to be vented from
the production area.
Diazo duplicators for roll formats contain a UV lamp and a transport
mechanism to move the copy and master film in contact through the light
beam. The films then separate, the master is re-spooled and the copy film
passes into a chamber filled with ammonia gas where the latent images are
Diazo duplicators for flat formats may be fully automated, but many are in
two parts. In the first section the master and copy film are held in contact
and exposed to UV light. The copy film is then manually removed and placed
in a developing section where it is exposed to ammonia. In some cases these
two operations are performed on separate machines. In this case the first of
the two sections is described as an exposing unit and the second as a
Diazo copies are less susceptible than silver halide film to damage by dirt,
finger marks or scratching as the image is more integral with the film. They
are not used for archival applications requiring the maximum possible
storage life, but they are certainly reliable for most commercial
applications and if protected from long-term exposure to UV light they are
suitable for applications requiring storage for up to 50 years or more.
Thin base polyester film is often used for 16mm diazo copies. It permits
double the length of film to be held in cartridges and cassettes than normal
thickness silver halide material. Thin base film is unsuitable for fiche and
jacket copies because it lacks the necessary rigidity.
Dry diazo film incorporates a developer in the film coating and only
requires heat to release it and develop the image. For fiche and jacket
duplication it is also possible to employ DOD paper coated with encapsulated
developer which is released by heat. These materials avoid the use of liquid
or aqueous ammonia but add to the cost of duplication.
Vesicular film is similar to diazo film in many of its characteristics. It
too employs diazo compounds, but the light sensitive content is incorporated
in a thermoplastic colloid.
When exposed to UV light and then heated to about 130ºC the diazonium salt
releases nitrogen gas and forms minute bubbles within the emulsion layer.
These bubbles scatter light and appear as dark areas on the enlarged image.
Unexposed areas are clear after development, so the film is sign-reversing
in that a master negative film will produce a positive vesicular copy and
The advantages of vesicular duplication include the absence of liquid
chemicals, daylight handling and its sign-reversing characteristics which
enable COM film to be conventionally processed to produce a positive master
and then reversed to negative distribution copies. Vesicular film has
reasonable resistance to scratching but is inferior to diazo in these
respects and if positive duplicates are produced from negative camera film
they tend to show finger marks and dust. While 3rd generation duplicate
copies can usually be produced from diazo films, it is difficult to produce
subsequent copies from a vesicular film, although it produces good paper
Vesicular film duplicators are similar to diazo units and some machines can
accept both materials. The difference is that vesicular film only requires
heat to develop the image after exposure to UV light, so the developing
section of the duplicator does not need to contain ammonia.
Experience confirms that vesicular copies are adequate for most commercial
applications although they are not normally recommended for applications
requiring more than 25 year storage life.
Silver halide copies are normally sign-reversed so that a negative master
produces a positive copy, but direct-duplicating silver halide film is also
available which does not reverse the image polarity. Alternatively, it is
possible to use reversal processing to produce negative copies from negative
Silver halide duplicating film, processed in accordance with BS/ISO
requirements, is fully archival with a claimed storage life in of 500 years -
much longer than the paper on which most of the original documents will have
been printed. It has a far wider tonal range than diazo or vesicular
material and is therefore more suitable when the master film contains images
with illustrations requiring this characteristic. Silver duplication is
widely used in libraries and archives where maximum storage life is an
Silver film duplicators usually only expose the copy film in close contact
with the master. Subsequent image development is in the same type of film
processor as is used for original camera film. The duplicator must either be
located in a dark-room or fitted with light-tight cassettes to hold the
duplicating film as it is very sensitive to daylight both before and after
exposure and prior to fixing.
Film duplicators fall into
two categories. Roll to roll duplicators accept a roll of 16, 35 or 105mm
master film and a roll of copy film of similar width. Sheet to sheet, or
card to card duplicators produce fiche, jacket or aperture card copies.
To automate the copying process, some duplicators designed for fiche and
jacket duplication contain a roll of 105mm duplicating film and cut it into
separate A6 copies. Aperture card duplicators usually hold a stack of master
cards and a stack of diazo copy cards, ready mounted with unexposed diazo
film; a method of reproducing printed or punched data is also usually
incorporated to generate exact copies of the master cards.
With hand-fed units the speed of duplication largely depends on the skill of
the operator. Some units can expose several fiche or jackets together to
speed up the process, development can be carried out in one section while
exposure is taking place in the other.
Quality control and
Quality control and finishing
operations require cartridge loaders, densitometers, inspection stations,
film cleaners, jacket fillers and splicers.
The quality of the films being produced or duplicated must
be monitored and equipment is available to assist and speed the process. If
old films are to be duplicated it is sensible to put them through a film
cleaner prior to duplication to prevent dust marks on the copy film.
Inspection tables for use
with roll formats often incorporate cartridge loaders and
space may also be provided for a film splicer. A magnifier or full microfilm reader may be
incorporated to assist verification and a powered take-up spool with foot
control is a common feature for roll applications.
In order to meet the conditions set out in BSI/ISO Standards for archival
permanence, silver halide film must be processed under strict quality
control. The aim when exposing, processing and duplicating microforms is to
achieve consistent results so that each image is easy to read and good
quality prints can be produced without adjusting the printer. If all images
are of near identical density good results can also be obtained from image
scanning with no need for test runs.
The density of silver halide images is measured with a
meters the amount of light transmitted through the material. Clear areas are
never perfectly transparent and some light can always pass through the dark
areas. A typical standard might call for a background density between 0.9 to
1.1 with negative film and a base fog density in the clear areas below 0.12.
For most applications it is best to aim for a background density of around
1.0. To simplify testing it is normal to film test patches at the start of
the film to provide large areas from which readings can easily be taken.
These can be incorporated within a test target which also includes five or
more resolution test charts.
Several variables can affect the density of microfilm images, these include
the lighting on the camera, the temperature and strength of the developing
solution and the length of time that the film is in contact with the
developer. Camera lamps produce less light as they age and they should be
regularly replaced; processing chemicals require replenishment to ensure
A reliable bureau will process film to within very strict limits and this
greatly assists quality control, since any variation will almost certainly
be due to the filming operation. The most effective test is to expose a
series of frames altering the camera lighting by one step for each frame.
After the film has been processed the best frame can be identified and the
setting used to produce it can be adopted for all film of the same type and
make. The test must be repeated periodically to ensure that ageing of the
camera lamps is not causing a variation.
If processing is conducted in-house, special pre-exposed “test wedges” are
available from all film suppliers. These are simply short lengths of film
which has been very precisely exposed. Any variation in the result of
processing a test wedge must, therefore, be due to the processing operation
as it can not be caused by exposure.
Resolution test targets permit the examination of processed film to see how
well closely spaced lines are defined. Good quality test charts are
essential and the standard for them is strict. They contain a series of L
shaped nested patterns in which the line thickness and the space between the
lines is equal, the size of the patterns reduces progressively and the
resolution of the image is defined as the number of the finest pattern in
which separate black and white lines can be distinguished, multiplied by the
reduction ratio used when the chart was filmed. Test charts are particularly
useful for checking duplicate film as they permit measurement of any quality
loss in the duplication process which should not exceed one pattern.
Resolution test targets are examined with a microscope which should have a
maximum magnification of about 100X. The actual magnification employed
should be between 0.5 and 1.0 times the number of line pairs per mm expected
on the smallest resolved pattern. The minimum acceptable resolution will
depend on the reduction ration employed so that with documents filmed on
fiche at 24:1 the 5.0 pattern should be resolved on the master film and the
4.5 pattern on a copy film, while drawings filmed at 15:1 require minimum
resolutions of 7.1 for the master and 6.3 for a duplicate copy.
The life of silver halide film is determined by the
conditions in which it is stored and the amount of thiosulphate remaining in
the emulsion after it has been processed. All reputable bureaux regularly
test for residual thiosulphate and many will accept films produced
externally for testing. The procedure is rather too complex to be undertaken
by the normal in-house microfilm unit.
Duplicate film must be examined to ensure that it is of
adequate quality. Silver copy film is subjected to the same tests as camera
film. The density of diazo film can be measured using suitable filters, but
readings are less precise because different densitometers can produce
different results. Nevertheless, for internal quality control where all
tests are made on the same instrument, diazo film density can be monitored
with the aid of a densitometer and a microscope can be employed to measure
the resolution of duplicated test patterns.
Similarly, the characteristics of vesicular film give rise
to variations between different instruments, but densitometers are available
which permit satisfactory monitoring of vesicular film density for internal
quality control purposes.
All film production operations should be conducted in a
clean environment. If film that has been used in reading equipment requires
duplication it should first be passed through a film cleaner to remove any
dust it may have accumulated. Staff should wear clean cotton gloves when
handling film to avoid fingerprints and particular care must be taken to
ensure that processed film is not handled with gloves that are dampened by
contact with chemicals.
The majority of modern microfilm applications rely on a
bureau for filming, processing and production. Quality control then becomes
the responsibility of the bureau, but it is sensible to insist that regular
tests are conducted and to ensure that test charts and density patches are
included at the start of each roll so that quality can be monitored
Modern micrographic materials have considerable tolerance
so that it is not difficult to produce consistent results, but tests are
desirable before any substantial quantity of unusual input is filmed,
particularly if it involves coloured paper or faint carbon copies.
Those responsible for the in-house production of
microforms should closely adhere to British or ISO micrographic
standards, most of which are now
Very few new jacket applications are reported because
electronic document management systems are superior for systems requiring
constant addition to individual records. There are, however, large
applications still in use and this creates a small demand for replacement
jacket fillers. As these machines have few moving parts this market is
largely being filled by reconditioned units.
are needed to join separate lengths of roll film, the two popular widths
being 16mm and 35mm. A splice may take the form of an adhesive patch or a
weld. Adhesive splices. which may be supplied as separate tabs or in roll
format, can be used on any type of film. Ultrasonic welding has the
advantage of not increasing the film thickness, It is excellent on polyester
film but it is not suitable for some acetate film bases.
Microfilm Readers and
optically enlarge the microfilm image for viewing only. Input may be limited
to one microformat but many models can accept multiple formats by using
adaptors to hold different types of film. Motorised
film transport facilities normally relate only to roll formats.
As a general rule, readers with square or portrait shaped screens are
suitable for camera-filmed documents - if they are fitted with an image
rotation facility they can display images in comic or cine-mode. Those with
wide screens are used for COM generated film and (for large screen models) the
simultaneous display of two portrait pages. An alternate method of reading
microfilm is to scan the images and convert them to digital data which can
be displayed, copied, stored or distributed on a computer system. Film
scanners are available for all formats.
Microfilm Reader-Printers -
Optical reader-printers enlarge the microfilm
image on to a viewing screen and can produce a print directly without being
connected to a computer system. They are only suitable for small to medium
volumes of printout. Factors to consider include the choice of lenses, film
carrier options, image retrieval methods available and the cost of prints. Features
include the ability to rotate the image, alter image polarity, mask any part
of the image, correct skewed images and superimpose repetitive data on
prints. As with readers, the trend is towards the use of film scanners to
digitise microfilm images which can then be displayed or printed out using
conventional computer systems.
Those seeking paper printout from microforms can obtain
A4 or A3 prints from the majority of the
microfilming services listed in this
website. Large format printout from microfilm is a more specialised
operation and suitable providers will be found under
large format printout.
These are available for low volume applications requiring
occasional reference to microfilmed images or large volume conversion of
film to digital format. Data sheets are provided for the models available in
the UK under aperture card scanners,
roll film scanners and
universal film scanners which can
accept any microform but may involve the use of adaptors.
Used and reconditioned
Obsolete, second-hand and
reconditioned micrographic equipment is widely available. Some machines are
no longer being manufactured due to low demand, but a flourishing
second-hand market in the UK offers fully reconditioned units and obsolete items.
Our listing is not comprehensive but most of the main suppliers will be
found under Used and/or Reconditioned Equipment.
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2. Microfilm today
Input and output