Maintaining standard scales of reproduction in patient photography using digital cameras

The use of standard representational photography of patients and the control of the variables in that process, have long been the factor that separates the professional medical photographer from the DIY enthusiast. The published recommendations on how standard representational photography can be set up and maintained have been based on the use of 35-mm film cameras. The common use of digital cameras in departments of medical illustration have brought with them new problems, one of which is the variability of size of the CCD fitted to these cameras. As CCDs are, at the time of writing, smaller than the 35-mm frame size, established protocols need to be changed. This problem can be compounded if a department uses more than one type of camera, each with a different CCD. This paper sets out a method for calculating and calibrating the new scales of reproduction required for digital cameras.