Pyro & selenium toning of negatives

"Lew" wrote in message
t...
there is a limit beyond which there is some, or even
total, loss.

Please explain. I see no reason why the chain of copying
the most recent copy should ever end, even using today's
materials.
-Lew

If you mean digital storage, there is some loss every time
material is transferred. The error correction routines can
regenerate a lot of lost data, but, if enough is damaged, it
can not be regenerated, however, current methods are pretty
rugged.
Any real archival storage, that is storage expected to
last for centuries, will need continuing care so I am not
sure digital is really at such a disadvantage in this
regard.


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Richard Knoppow
Los Angeles, CA, USA

I respectfully disagree. If I remember my technical readings from some years
ago correctly, when data is transferred between media checking routines
verify that the bytes that appear on the target media match those on the
source. Implementations of this idea further include checking the memory
used to buffer both sides of the transfer. Theses methods are employed
because the speeds of the source device and media, the speed of memory and
the speed of the target device and media are often quite different so a
"re-do it until you get it right" protocol is used. We call these
"error-checking" routines, but it's not correct to cite their existence in
support of the idea that some data is always lost. I am not aware of any
evidence that any other errors exist which can or do accumulate over time.
The only reasonable assessment I can see is that if the data on the target
media is a duplicate of source _after_ it has been removed from the copy
device, then we have a 100% accurate copy without loss. The existence of
these checking routines and their actually being used during a copy do not
constitute loss of data, they assure its accuracy.
Perhaps the photo archivalists who first read these explanations didn't
have the technical background to evaluate them, but as far as I can see,
unless newer information exists that I'm unaware of, the claims regarding
the inescapability of data loss are greatly exaggerated. The attendant
concern that the necessary software for reading graphics file formats may
disappear is equally incredible.The only limits I'm aware of stem from the
physical condition of media and the conditions under which they are stored,
not unlike photographic materials. Recommendations about redundancy and
recopying are valid.

"Richard Knoppow" wrote in message
ink.net...
f "Lew" wrote in message
t...
there is a limit beyond which there is some, or even total, loss.

Please explain. I see no reason why the chain of copying the most recent
copy should ever end, even using today's materials.
-Lew

If you mean digital storage, there is some loss every time material is
transferred. The error correction routines can regenerate a lot of lost
data, but, if enough is damaged, it can not be regenerated, however,
current methods are pretty rugged.
Any real archival storage, that is storage expected to last for
centuries, will need continuing care so I am not sure digital is really at
such a disadvantage in this regard.


--
---
Richard Knoppow
Los Angeles, CA, USA

Richard Knoppow wrote:
"Lew" wrote in message
t...

Eventually we well have digital storage methods capable
of centurys of life, but they are not available yet.



"Eventually"? So when my wifes' (theoretical) son gives *his* daughter a
CD-RW with a whole load of images on it, way after we have passed away,
that grand-daughter of mine will simply be able to put that CD right
into her computer and look at / print off the images, right? I mean, the
same way as I've some negs from *my* grandparents, yes? Of course, those
old negs of mine have deteriorated a bit, but the digital CD won't have.

Will that grand-daughter of mine actually be able to read a "CD"? Will
there still be those quaint "CD-ROM" drives around and working? Will
anyone actually remember what a CD-ROM was and be able to connect it to
their new imaging device?

Not that we have to worry, of course, since computer technology is
always advancing, with increasing reliability and ever-larger storage
media. I mean, everyone can still read the data off their 5-1/4" 360K
floppy disks, can't they? (I can). Even 8" 144K floppy discs are easy to
read off in a PC, aren't they? (I can). After all, that's only a few
years ago, so we must be all safe, mustn't we?

However I must leave it there, since I have to attend to some developing
in my darkroom, in which I use a hardening fixer for my B&W negatives
and a little formaline for my colour negatives. I think they'll still be
able to be seen and printed long after the CD-ROM has gone out of fashion.

My regards, F.C. Trevor Gale.