Sensitometric strips should be exposed to which type of light?

• A. X-ray light
• B. Visible room light
• C. Sensitometric light only
• D. Sunlight

Answer: (C)

Sensitometric measurements rely on a controlled, calibrated light source that’s specifically designed for exposing film to known amounts of light—the sensitometer. This light is uniform, stable, and selected to produce precise exposures without fogging the emulsion. Only this sensitometric light should illuminate the strips because it gives repeatable, accurate data for constructing the film’s density versus exposure curve.

Exposure to other light sources would ruin the measurement: X-ray light isn’t used for this optical exposure, room light would introduce unpredictable fogging and density changes, and sunlight is uncontrolled and intense. The result would be densities that don’t reflect the intended exposure steps, making the sensitometry data unreliable.