center is an asorbance of 0.5, corresponding to 0.1 mg of substance. The absorbance
scale is logarithmic, so that even from a digital display the readings are more reliable at
the low end of the scale. However, at very low absorbances one or more unknown
factors, such as a defect in the sample tube or cuvette, will have a more profound effect
on the absorbance value than at higher absorbances. At the upper end of the range the
color reagent approaches saturation, so that not only do you have less resolution among
absorbance readings, but the reagent is less sensitive to differences in protein
concentration