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Scratch Test: Difference between revisions
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A [[slap scratch]] or standing scratch occurs when the film slaps against a surface of the projector once per frame. The most common cause is an upper or lower loop being too big or too small, but slap scratches can also occur in the gate from excessive vibration or mechanical misalignment. | A [[slap scratch]] or standing scratch occurs when the film slaps against a surface of the projector once per frame. The most common cause is an upper or lower loop being too big or too small, but slap scratches can also occur in the gate from excessive vibration or mechanical misalignment. | ||
Vertical scratching can occur in the gate, on flywheels, on rollers | Vertical scratching can occur in the gate, on flywheels, on rollers, or simply by brushing against part of the projector. | ||
Some examples: | Some examples: | ||
If a straight vertical scratch appears near the center of the frame, the film is likely being scratched in the gate. Check that the lateral guide rollers are turning freely and that the studio guides are not too tight and are not pinching the film inwards. | If a straight vertical scratch appears near the center of the frame, the film is likely being scratched in the gate. Check that the lateral guide rollers are turning freely and that the studio guides are not too tight and are not pinching the film inwards. | ||