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TRIGGERING A PAIR OF MINOLTA DIMAGE 7's Prof. John Hart Program in Atmospheric and Oceanic Sciences University of Colorado Boulder, CO 80302 December 2001 nimbus.colorado.edu/hart/science.htm
In our laboratory at the University of Colorado we have tested parallel triggering a pair of 5 megapixel Minolta Dimage 7 digital cameras. The scientific application is two-camera 3D imaging of rapidly moving turbulent flows where flash freezing of the motion is critical. Tests were done to see how well digital cameras can be synchronized. The D7 camera is fired by a hardwired remote switch, the RC-1000. For applications in fluid dynamics, of viewing turbulent flows at different angles, or in 3D, it is important that the cameras fire simultaneously. In these tests two cameras are attached to the same switch (see the Twin-Cams page). They then shoot images of a rapidly rotating wheel (going at 4 Hz.) The images are read to get the interval between pictures for the two cameras.
Figure 1. The test setup. Each interval on the screen scale corresponds to 1/80 sec.
Figure 2. Results of the tests. Left camera Lead vs. reading. Conclusions: These tests were done using Manual Mode (where both shutter and aperture are preset). For this mode synchronization is better than plus or minus 1/30 of second. This is not good enough to use flash. There are some periods where the synchronization is quite good (e.g. around 80 on the horizontal axis). The reason for this sort of behavior is described in detail in the Coolpix Technote. Other exposure modes behaved poorly, with errors routinely of order 0.2 seconds. Not recommended for close -triggering applications. |
