Buried into another discussion was the possibility of using optical flow sensors for sensing film transport, and alternatively also for detecting sprockets.
The initial response was the complication of Optical Flow Sensors (OFS) to contact the film, in the case of sprocket detection. But later I found other OFS that use optics to avoid surface contact.
The ADNS3080 specifications indicate is capable of 6400 frames per second (fps) and detecting surface changes of 40 inches per second.
Here is an interesting video combining the use of OFS and laser for robotics… I think these are promising ingredients for an alternative approach to sprocket sensing.
Short term I do not have the bandwidth to prototype one, so the purpose of this topic is to explore alternatives and feasibility of using these. Seeking feedback in case anyone have experimented with these.