Lighting and Exposing for HD
17.1 An HD Camera’s Equivalent ASA Speed, or ISO Rating
I check the speed, or sensitivity, of any High Definition (HD) camera using the same technique I would use when testing a film stock’s ASA (American Standards Association) or ISO (International Standards Organization) rating. Note that the numbers will be the same. When checking a film stock’s ASA speed, I set the camera up facing an 18 percent reflectance gray card and make a range of exposures, noting the setting on my meter for each one. Then I ask the laboratory to make me a middle of the range one-light print. Whichever exposure most exactly matches the tonality of the original gray card I deem to be the correct rating for that particular film ...