Identifying Physical Defects
Remember that defects in the film depend upon:
- the chemical and physical properties of the different bases and emulsions
- how it has been processed or printed previously
- - how it has been treated in a projector [if it is a print)
- - how it has been handled by an operator [probably the greatest risk]
- - the conditions in which it has been stored
In order to view the physical state of the film most technicians use either a simple still frame projector fitted with a roll film holder [sometimes called a diascopic film checker] or use a x10 hand lens over a flat bed winder. There is a lot to be said for both systems but in motion picture laboratories a hand lens is most widely used as it allows the assembler to view both emulsion and backing of the film separately by reflected light which gives the best views of scratches and dust and surface defects. An archivist is more interested in the picture and so more often uses a projection viewer. A black cloth is sometimes used as a background for viewing surface defects.
Increasingly as the quality of modern film processing improves, many laboratories use binocular microscopes with x10 to x60 zoom lens systems and fibre optic light sources. These are rarely necessary for old archive films but will be increasing necessary as the quality of film increases. Eventually the almost blemish free images of today will have to be reconstructed in the archive!
