I was talking about using the same time steps numbers as apperture numbers which some people do with paper exposures of test strips (i.e. 2.8, 5.6, 11, 22 are not accurate doubling steps whereas 1/25, 1/50, 1/100 are strict one stop steps in time). Of course 2, 4, 5.6, 8, 11, etc... are accurate F numbers for doubling the amount of light with fixed exposure time. I was wondering about the time steps, nor apperture steps in camera.