In the digital photography system, the tonal characteristics of the system is evaluated by Camera-Through Sensitometry: CTS as the traditional photography. The tonal characteristics of reproduction image on the CRT monitor shot by digital steel camera, DSC was directly measure by colorimetric analysis. The lightness data on the displayed softcopy image of lightness linear single color step charts showed linear relation with the input data level. The slope of those characteristics indicated the qualitative tone characteristics of DSC. That relation for the chromatic magenta color chart was more distinctive than that of achromatic black and white step chart. The slope was also closely related to the tonal characteristics of reproduced object image on the photo-prints shot by DSC and reproduced by digital color printers.