+(defun coc (imager-size &key (lpm 5) (minimum-distance 250)
+ (viewing-distance 250)
+ (print-size (output-dimensions :8x10in)))
+ "Returns circle of confusion in mm and print magnification for a format.
+Default resolving power is 5 lpm at 25cm."
+
+ (let* ((imager-max (max (car imager-size) (cdr imager-size)))
+ (imager-min (min (car imager-size) (cdr imager-size)))
+ (print-max (max (car print-size) (cdr print-size)))
+ (print-min (min (car print-size) (cdr print-size)))
+ (magnification (max (/ print-max imager-max) (/ print-min imager-min)))
+ (resolution-factor (/ (* magnification lpm minimum-distance) viewing-distance))
+ (coc (/ 1.0d0 resolution-factor)))
+ (values coc magnification)))