Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "jakapecki" <jakapecki@...> wrote:
>
> In his discussion of "Kodak Years" vs. "Wilhelm Years", Mark uses the word "assume" with respect to ambient light levels. That needs some explanation. Kodak chose its 120 lux light level (for a 12 hour "day"), not by just assuming that value, but by doing the largest study of its kind ever undertaken, measuring light levels (along with temperature, humidity and ozone) continuously extended periods of time in a statistically-chosen sample homes throughout the world. The results from these millions of measurements were published in a referred, scientific journal so that other photographic scientists would know why, how, and where the data were collected. No one else has done this. Others have chosen their assumed lux level on the basis of single-reading spot measurements (which can vary by a factor of 1000 during the day) and without seasonality effects, which can also induce large variations. 


Jon ["jakapecki"], you are a very smart guy, and when we were both involved with the ISO committee's work on a new light fade testing standard, I took many of your comments and criticisms about the WIR 450 lux level to heart. They definitely influenced how I set up my own light fade testing protocols at AaI&A.  If you can still pass along this information to your colleagues representing Kodak on the ISO committee, I humbly suggest that AaI&A has offered WIR, Kodak, and the ISO committee a logical way out of this long standing pissing contest about who's average light level is the better one to use as  a "normative" light level in the real world.  Simply report megalux hours of exposure rather than "extrapolated years on display", provide an appropriate exposure dose-to-display environment conversion table (as AaI&A has done), and this absurd debate is resolved.  As for trying to integrate all the possible additional print degradation pathways together into a one-size-fits-all print life prediction, well, you and I both know that's a fool's game.

Cheers,

Mark
http://www.aardenburg-imaging.com