Speed accuracy of some camera drive systems
Tobin Cinema Systems crystal motors: ±3 ppm (0,0003%)
Cinema Products CP-16R: ±8ppm (0,0008%)
éclair ACL 1: ±50ppm (0,005%)
éclair ACL II: Thomson CSF motor ±8ppm (0,0008%)
éclair NPR: Perfectone CIBLO motor ±200ppm (0,2%), BEALA motor ±10ppm (0,001%)
ppm stands for parts-per-million.
AatonCode Glossary tells the ppm as the ratio of frequency deviation with respect to normal frequency. It refers to the accuracy of the electronic crystal inside each Timecode capable device on set. The lower the number, the more accurate over time the device. The more accurate the device, the less Timecode drift will occur over time.
The accuracy of the crystal used in all Aaton cameras and Timecode generators, as well as the crystal used in a growing number of DAT recorders (such as the HHB with MS1000 Timecode module) is rated at 1ppm. This translates to an accuracy of approximately 0.5 a frame drift or less over 7 hours.