[LRflex] Re: Breathing easier, now.

  • From: David Young <dsy@xxxxxxxxxxxxxxx>
  • To: leicareflex@xxxxxxxxxxxxx
  • Date: Thu, 05 Feb 2009 07:52:42 -0800

Guilherme wrote:


Hi Miha
I agree with you that the laser is thinner, about 50%, but this carachterists about blu ray disc is real. It tends to disperse the laser in a lower degree because the thinner filter on the surface and with the near laser cannon with the data you won't have inclination problems like with dvd. 

Hi Guilherme!
The thinner laser does allow more data per disc and the different wavelength may prevent/reduce some of the dispersion problems.
However, the main problem with home recordable DVD's and CD's is that they use a thin layer of organic dyes, which turn dark when exposed to the laser. 

This leads to several problems:
1) If the discs are exposed to light, the lighter areas can darken, corrupting the data.
2) If a disc is dropped, or suffers any damage in manufacturing or during shipment to you, microscopic cracks can occur, which allow air into the organic dye layer, leading to premature failure.
3) over time, air seeps through the polycarbonate layers, by osmosis, causing failure of the dyes. This is the main reason why recordable DVDs & CDs have a finite life.
My understanding, from reading all the links given here as well as other materials. seem to say that the write once, Blu-Ray recordable discs burn ridges into a paper substrate. This, it would seem to me, would be more reliable, in the long term, than dyes. (More stable - less susceptibility to exposure to air and light.)
The flaw is that the protective polycarbonate layer is much, much thinner than on DVDs or CD's, making Blu-Ray discs much more susceptible to physical damage. There is a lot of discussion about how various makers have been developing hard, anti-scratch coatings for their Blue-Ray discs ... something not needed for DVDs and CDs.
However, re-recordable Blu-Ray discs use organic dyes, like DVD's and CDs, which, combined with the smaller pit area, would potentially lead to more problem, not less. 

So, it seems the Jury is still out on this one.
For myself, I will avoid Blu-Ray until it is more proven, simply because of it's increased capacity. It becomes more like a Hard Drive... if it fails, many more photos are lost. Thus, there is still a need for multiple backups. Personally, I will stay with 3. One for daily use. One for backup. And one archived in a friends basement, to protect the photos in case of fire or theft.
All this being said, I will be happy for someone to show me my concerns are groundless; and I look forward to hearing how the Blu-Ray works for you, Guilherme. Please do let us know! 

Cheers!
---

David Young,
Logan Lake, CANADA

Limited Edition Prints at: www.furnfeather.net
Personal Web-site at: www.main.furnfeather.net



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