Back focus adjusting mechanism for imaging camera

A back focus adjusting mechanism for an imaging camera including a camera housing, a lens mount protruding in the camera housing and including a cylindrical portion formed with a guide, an imaging element and an imaging lens, the back focus adjusting mechanism comprising a coil spring provided around the cylindrical portion of the lens mount, an imaging element holder holding the imaging element so that the imaging element is moved along an optical axis of the imaging lens by the guide of the lens mount, an adjusting ring provided with a cam the imaging element holder engages and a positioning holder fixed in the camera housing and positioning the adjusting ring so that the adjusting ring is rotatable around the cylindrical portion of the lens mount, the imaging element holder abutting the cam by rotation of the adjusting ring being moved, the back focus adjusting mechanism further comprising:

• a spring member pressing the adjusting ring against the positioning holder and fixed in the camera housing;
• and
• a knob member operated outside the camera housing,
• wherein the adjusting ring is fixed at an adjustment position while being subjected to a pressing force of the spring member by the knob member.