Видимо, имеется в виду следующее: EI=1.20 для кадра № 12.

SpeedIndex, or Mid-Density, is an indication of the processor-film-sensitometer combination speed. It ismeasured at the ***step*** on the sensitometric film with an optical density closest to 1.0 above base + fog (ifthe base + fog optical density is 0.18, speed is measured at the step having an optical density closest to1.18). This ***step*** may be somewhere around ***step 11*** on a 21-step sensitometric strip.
http://www.crcpd.org/PDF/12-92qac.pdf

EI - Exposure index - is the film speed setting that should be used practically with a film to allow for the conditions of exposure and development.
photography.about.com/library/glossary/bldef_ei.htm