Does anyone know what the film speed factor is for a Leitz yellow-green (marked GGr) filter?

-- Steve Jones (stephenjjones@btopenworld.com), March 20, 2002

Answers

It is simple to figure out. Point a handheld meter at a grey card and take a reading. Now take a reading through the filter. Divide the first reading into the second and you have your filter facter. Test under the different lighting conditions (overcast, sunlight, tungsten, etc) as the filter facter will vary with light temperature.

Films also have different spectral response so you may have to adjust your facter depending on which film you are using. Test, test and test.

-- John Collier (jbcollier@shaw.ca), March 20, 2002.