Thanks Gary

am going to repeat as although results were nearer to expected a few were a little off in the "correct exposure" that is the figures in the blue channel were lower than the red and green

I have 131 132 and 116 at 1/60s, these changed

at middle to 131 130 110

at lower left to 125 124 and 103

which makes me believe that the light across the card was not uniform.