Gregory Fraser <Gregory.Fraser@pwgsc.gc.ca> writes: > Why is the illumination difference in a 3:1 lighting ration 1 1/3 stops and not 1 1/2 stops? Is it because the f-stops on cameras and meters tend to be divided into thirds or is there a mathematical reason? Is it? According to my own [^_^] calculator... http://imaginatorium.org/stuff/stops.htm ... if you put 1/100 and 3/100 second exposure times, which presumably means a 3:1 "lighting ratio", then the difference in stops is 1.585 stops. Cross-check: 1 stop means "x2", so 0.5 stops means "x sqrt(2)", so 1.5 stops is an exposure ratio of approx. 2x1.4 = 2.8. So indeed 1:3 must be _more_ than 1 1/2 stops. What you wish for is the reason Japanese B paper sizes are wrong, and copiers need twice as many different reduction ratios as they do in a properly rational country (z.i. Churmany). <rant>Must write that thing about paper one day... Error: <rant> tag not matched. Brian Chandler ---------------- geo://Sano.Japan.Planet_3 Jigsaw puzzles from Japan at: http://imaginatorium.org/shop/
