Message text written by INTERNET:[EMAIL PROTECTED] >Nope nope 18% is not in the center, unless you say white paper can not relect mor than 72%. As you can see above 12% is the center of a 7 stop range and 6% is the center of a 9 stop range. Actually, IIRC, Adams selected 9% as zone V which would make 18% zone VI.<
it's based on what will reproduce on decent slide film. 5 stop range where 2 1/2 stops above average will be featureless white and 2 1/2 stops below average will be featureless black. 18% is half way on that scale. table and chart on page 25 of John Shaw's Nature Photography Field Guide. optical density range on my Gretag Macbeth Color Checker is 90% reflectance for pure white and 3% reflectance for pure black. total range is about 30x or about 5 stops. Herb...
