>>4374476One more paper worth reading:
https://cdn.shopify.com/s/files/1/0143/5772/5241/files/SMPTE_HSStress.pdf>Eventually, the theory surfaced that fluctuations in tension on the film as it negotiated the right angle turn around the "Feed Idler Roller" immediately prior to engaging the drive sprocket were causing localized alterations in sensitivity of the emulsion. And the theory of High Speed Emulsion Stress Syndrome was born.>A hypothesis developed that the new tabular crystal structures, being relatively very thin, could actually be subject to fracturing and breaking if bent around a tight radius. This concept seemed a little far fetched, but the consequence of such an event would be consistent with the effect, in that the film exhibited a localized desensitization. Consider that if one could actually break one large crystal into two or more smaller ones, one would create a finer grained and slower emulsion, at least where the breakages occurred.>However, this theory was confounded when it became apparent that the desensitization was also transitory. That is, if the stress were applied and the film then allowed to "rest," it would recover its normal sensitivity. The tests at Apogee included both pre-stress tests and post-stress tests, and neither pre or post stress caused the same desensitization effect.>Eventually the hypothesis was modified to satisfactorily account for the transitory nature of the effect. Actual breakage of the crystal probably does not occur. Instead the crystal responds to the applied stress of bending around a tight radius in much the same way that piezoelectric crystals do: it transfers energy—electrons—temporarily. Thus, when the film bearing such crystals arrives at the camera gate for exposure to photons, it is simply not itself. The photons it absorbs under such conditions are unable to change the state of the affected crystals as they would normally and so some crystals remain - unexposed.Fascinating stuff, if you ask me.