On Wed, Mar 18, 2009 at 1:27 PM, William Robb <[email protected]> wrote: > > ----- Original Message ----- From: "Adam Maas" > Subject: Re: has anyone tried optibrite with a katzeye screen? > > > > > Many of the people over there still think that camera meters are > calibrated for 18% gray just because that's what Kodak gray cards are. > > Funny you should mention that. > I've never been able to get a straight answer. I've heard 12%, 18%, and a > few other numbers. > What is the reflectivity standard for meter calibration? > > William Robb >
The ISO standard is variable (there's a range of valid choices), but 12% is the most common for reflective meters in cameras although 16% is anothr possible result using the most common calibration constants. 18% is within the possible range (and given the common choices in values for C and K, the incident and reflective calibration constants, 18% is likely correct for the Pentax Spot Meters) -- M. Adam Maas http://www.mawz.ca Explorations of the City Around Us. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
