Abstract:
An apparatus for detecting an edge opening (22, 24) in a web (12) of photographic film includes a frame (84, 138, 140); an edge guide (156, 158) supported by the frame, the edge guide having a surface (160) for engaging an edge surface of a web moving past the edge guide; an aperture (334) in the surface; a guide track (325, 327) supported by the frame; an optical sensor (328) mounted on the guide track, the sensor comprising a probe (330) extended through the aperture to a point near the surface; and a mechanism (318-322) for moving the sensor along the guide track to position the probe for accurate detection of an edge opening.