The loss of definition resulting from geometric factors of the radiographic equipment
and setup is refered to as “geometric unsharpness”. It occurs because the radiationdoes not originate from a single point but rather over an area. The three factors
controlling unsharpness are source size, source to object distance, and object to
detector (film) distance. The effects of these three factors on image defenetion is
illustrated by the images below (source size effect; compare A & B, source to object
distance; compare B & D, and object to detector distance; compare B & C).