You're right... I am talking about doing slide shows on a DVD player for Presentation purposes only... As far as for image archiving any format will keep the same quality level that you saved the file in.
I would like to see some reports on how long home burnt DVD's are supposed to last from a reliability standpoint though. As all storage mediums can become corrupted over time. Personally I love the Idea of backing up my images to DVD's but I am a little leary of it yet without keeping things on a separate hard drive as well and the same for CD's but to a much lesser degree as the data density is much lower so slight degradation in the media would have a much less severe effect on the data. A little food for thought based on the different storage technologies, this pertains to CD's but I'm pretty sure that the technology is the same for DVD's, only the density is increased:
The Differences:
Pre Recorded (ie Store bought with Data on them):
The pre-recorded CD's that we buy are quite different in construction from the ones that we burn ourselves. In the case of these CD's the plastic on the CD is encoded with pits and flats that are then coted with aluminum that a laser can be bounced off of and read (ie pit= No reflection, Flat= Reflection- the equivalent of binary "1" and "0" which is how all computer data is stored). This makes for a very durable CD as the data is written into the Polycarbonate of the disk itself, which is hard to damage and very slow to degrade.
CDR:
With CDR's there is a major difference in how your data is stored from the above mentioned Pre-Recorded CDs. Have you ever wondered why we use the term "Burn" to make a CD? Well here's the explanation... CDR's have a completely flat data track which has a layer of organic pigment on top of it. This pigment is special in that it is clear until heated and then darkens. On top of this layer is a layer of aluminum to give the reflective background for your CD's laser to bounce off of. When we "Burn" a CD your CDR drive's laser intensity is raised high enough so that when it fires is burns a dark spot in the pigment.. this is how the data is written Dark spot=lower reflection through the burnt pigment (incidentally with about a 20% decrease in the difference between the two states compared with a manfuctured data CD). Does this impact data pernanence? YES Definitely! First the pigment layer does age and will discolor over time... I have heard life expectancies of 5-10 years, but have never seen good hard data on this, and for good reason- CDR's life expectancy can vary widely based on what kind of heat the CDR is exposed to, as well as Humidity etc. (I even read in a tech forum one time about people in some tropical areas having problems with microbiological degradation.. ie microbes eating the organic dye layers of CDR's and causing data loss in extreme storage conditions). So I would take it that CDR's have decent but not permanent longevity provided they are stored properly in a cool / dry place.
CDRW:
CDRW is yet another completely different technology from CDR. In this case there is no organic dye, but instead the metal reflective layer is special and melts at a lower temperature. In this case your CDRW drive's laser has two power levels it uses to write and re-write. The higher level heats the metal on the CDRW disk to a fully liquid state so that when it cools it has a mirror surface, and the lower power setting heats the metal layer of the CDRW disk to a semi liquid state so that when it cools it becomes rough / foggy (for those familiar with soldering the difference is equivalent to a good vs a "Cold" solder joint). This is why you can re-write, you can go back over your data with the higher laser setting and re-mirror the surface to erase the data. Additionally with CDRW's there is even less of a difference in reflectivity between the rough and smooth areas on the CDRW disk than with either of the other two (with about a 40-60% decrease in the difference between the two states, which is why some older CD drives will not read a CDRW as they are not sensitive enough to detect the difference). I believe that this format may be more durable than a regular CDR since there is no organic layer to age, but I am not sure which of the two is more temperature sensitive from a degradation perspective.
DVDR / DVDRW's:
As I mentioned before, I don't believe that there is any difference in the way that DVDR/DVDRW's are burned, I believe the only real difference is more precise control of the laser and better electronics, as well as a finer grade of metal or pigment used in the disks manufacture (ie smaller grain size for higher data density). So the same principals should apply with slightly higher risk due to the fact that the more dense the data is, the less degradation to the physical media it takes to cause data loss / corruption.
Sorry to be so long winded, but I really wanted to share this info, as there really isn't a perfect solution to long term archiving aside from keeping your data in multiple formats And preferably in physically separate locations. And I know for me it would be a big personal tragedy if all of the images and slices of time that I have captured of my Children's childhood were lost. Especially since that's the main reason most of us take pictures in the first place... to preserve a moment in time.... So burn some DVD's or CD's, but if you want to do the long term guarantee thing I would either rent server space as well, or buy a good external hard drive (until replaced by somethig better) and keep multiple copies of all the special stuff. Thanks, Milan
