Sorry for the blabla ;)

Olivier Thereaux (30 sept. 2007 - 16:41) :
> silver-based negatives, if properly stored, have a life expectancy
> clearly surpassing that of a DVD or hard drive.

Let's say that the digital age has not been long enough yet for  
proving this. ;)
150 years versus 50 years. It depends on which level we are talking.

  Information      Material Support
1 photo grain      film negative
2 photo code       dvd
3 photo code       magnetic system/hard drive

three cases,

1. traditional photo. The photo is part of the medium. The photo  
doesn't exist outside of the film negative and can't be reproduced in  
any way I think. If the negative is destroyed, the photo is destroyed  
for good.
It is high quality, and the information is partially accessible by  
eye with *mechanical* tools.  (very important in an unplugged  
scenario - global warming, etc. here insert here your catastrophe  
scenario)

2. Either coming from a film scan (loss copy) or a digital camera,  
the dvd is making a copy of the image on a device which is perceived  
as a permanent back-up. In fact it is not the policy for DVD should  
be the same than hard drives, and it's why it makes them in fact not  
practical. I think it might be the worse backup either, but has its  
own compacity for bookshelves and transportation. :)

3. Hard drive keeps somehow the policy of duplication and its  
automation a lot easier. The trouble for now is that there is no plug-
n-play system for the common consumer to back up system. Plus there's  
no real standard around archiving. A common format would help to  
develop software and hardwares which would work autonomously. If we  
keep reproducing the content of hard drives here and there, the life  
expectancy of the information could become longer than the film (if  
we still have energy for the devices.). The HD format doesn't matter  
as long as we keep transferring from hard drives to hard drives.

Never relies on only one hard drive.

The fact that the information on paper has a long life expectancy is  
not only because of the quality of the support, but also the fact  
that a text has been copied in many (book,magazine)-object and  
broadcast in many places. Here the strategy is not only to keep one  
copy, but many copies elsewhere in individual places.
Another strength. The information is accessible with our own eyes,  
without a reader.

> Pity one can't easily make duplicate negatives, though.

we can't. It is always a loss copy.


--
Karl Dubost - Tokyo, Japon
[email protected]