This message is in response to a previous subscriber who suggested that film archiving should 
be carried out digitally (my computer went wrong and I can't retrieve the quote)...
 
 
There are two reasons why not.  Firstly, by performing an analogue to digital conversion, you 
fundamentally change the image chracteristics produced by silver halide (or colour dyes) sitting 
on a cellulose nitrate base.  Admittedly, digital film manipulation systems such as Kodak's Cineon 
claim to offer a resolution comparable to that of 35mm film, but you will still lose the visual 
characteristics of the source medium by making an image of it on a totally different medium.
 
Secondly, what are you proposing to save the digits onto?  Magnetic tape has a notoriously low 
shelf life compared to that of film (hence the fact that many leading archivists believe that the 
only way to preserve video in the long term is by continual format migration, i.e. copying material 
at regular intervals).  Optical discs (CDs and the like) are still a relatively unknown quantity.  For 
all its faults, we have a mass of information about what happens to cellulose triacetate and 
polyester film when stored over long periods of time, and can reliably predict shelf lives of 100 
years or more.
 
It is possible to record digital data optically onto 35mm film (which is how the Dolby SR-D and 
Sony SDDS digital sound-on-film systems work), but surely it is better to archive photographic 
images photographically than change the way an image is stored when this is not strictly 
necessary.
 
Besides, not only is it better, it's a lot cheaper: someone recently told me that state-of-the-art 
digitisation of film images costs about $1,000 per 35mm frame.  Compared to that, a complete set 
of 35mm preservation masters (fine grain positive colour separations, internegative separations 
and colour internegative for both picture and sound) can be had for around UK£50,000
lot less if the film is black and white (thus only single-strip intermediate material is needed) and if 
there is only one type of soundtrack or the film is silent.
 
__________________________________
Leo Enticknap
Postgraduate Common Room
School of English and American Studies
University of Exeter
Queen's Building, The Queen's Drive
Exeter
Devon EX4 4QJ
United Kingdom
email: [log in to unmask]
 
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Online resources for film/TV studies may be found at ScreenSite
http://www.tcf.ua.edu/screensite