Errors in Streak Photography Measurements Caused by Subject and Camera Misalighment,

THAL MISALIGNMENT, THE TRAJECTORY TILTED RELATIVE TO THE CAMERA AXIS, AND IMPROPER FOCUS, RESULTING IN A MAGNIFICATION ERROR. For the velocity range of projectiles fired from the 4-in. air gun 400 to 800 ftsec and the optical parameters of the HDL streak camera, angles of trajectory cant up to 10 degrees and displacements of the trajectory by as much as 10 percent from the normal object plane magnification error result in velocity and acceleration errors of less than 10 percent. Trajectory tilt, however, introduces pseudo-acceleration into the photograph even when the projectile moves with uniform velocity. For a 10-degree tilt angle, the pseudo-acceleration may be as high as 120,000 ftsec squared. Author