On Sunday 22 May 2005 01:10 pm, Bob Friesenhahn wrote: > The most scientific description I have found for film > is available at > "http://wwwau.kodak.com/US/en/motion/support/h1/structureP.shtml";.
Figure 24 and the text describing figure 24 in the above is basically the Ansel Adams zone system. Zero is pure black and X is a specular highlight. Each increment represents one stop. Interesting to see how the more things change the more they stay the same. > There is also useful information in the document at > "http://www.filmlight.ltd.uk/documents/FL-TN-00-002.pdf";. > > Note that regardless of whether the film is mounted in your 35mm SLR > or part of a movie reel, the film is comprised of the same basic stuff > so there is likely general value for understanding its behavior. > > Even though digital cameras are currently the rage, a traditional film > camera coupled with a high-quality negative scanner should be able to > produce images with much better dynamic range. Bob is right on the money about the dynamic range of film. Let me add some detail. Most color negative films have 10 to 15 stops of dynamic range. Fuji Reala, which I use, has 15 stops of dynamic range. This is way beyond what is currently possible with single exposure digital technology which at best is about 6 to 7 stops. Color slide film typically has a dynamic of 7 to 8 stops. In high contrast scenes shot with slide film you are either going to blow out the highlites or you are going to lose shadow detail. You can not have good detail in both shadow and highlites and this is clearly true for single exposure digital technology. The old adage is expose for the highlites with slide film and expose for the shadows with negative film. I think that digital technology should be treated much the same way as slides with respect to exposure. In addition color negative film is fairly easy to scan as the density of the darkest (highlites) parts of the negative have relatively low densities compared to the darkest parts of slide film. In the above paper Kodak listed the Dmax of B&W negative film as about 1.8 where as B&W positive film (slides) was about 2.4. For color film these values are about 2.4 for negatives and 3.4 for positives. As you can see the difference in Dmax for color negative vs. color slide film is about 1 which is an order of magnitude. Many scanners manufactures claim to have a dynamic range that will handle Dmax > 4 some making claims as high as 4.6. But this is marketing hype and even the very best can only handle a density of about 3.5 before scanner noise becomes significant. The high Dmax of slides makes them hard to scan as the darker parts of the image will tend to have significant amounts of scanner noise and the noise will be in the darker parts of the image where it is more visible with anything but the very best film scanners. But even with modest low cost scanners color negatives with very high dynamic range can be scanned with very scanner little noise. It is still common for those that are shooting 360x180 panoramas to shoot with high dynamic range negative film because these scenes typically include both the sun and deep shadows. Even with film that is capable of a 15 stop dynamic range these scenes are a real challenge to photograph without loosing some much detail at either end of the spectrum. Digital photographers shooting these same scenes must resort to using bracketed multipule exposures and using special HDR software such as Photoshop CS to get enough dynamic range. Hal ------------------------------------------------------- This SF.Net email is sponsored by Oracle Space Sweepstakes Want to be the first software developer in space? Enter now for the Oracle Space Sweepstakes! http://ads.osdn.com/?ad_id=7412&alloc_id=16344&op=click _______________________________________________ Lcms-user mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/lcms-user
