What are the performance criteria for the processor densitometric evaluation?

• A. Base + Fog: +/- 0.10; Mid-Density: +/- 0.05; Density Difference: +/- 0.05
• B. Base + Fog: +/- 0.05; Mid-Density: +/- 0.15; Density Difference: +/- 0.15
• C. Base + Fog: +/- 0.05; Mid-Density: +/- 0.10; Density Difference: +/- 0.10
• D. Base + Fog: +/- 0.02; Mid-Density: +/- 0.05; Density Difference: +/- 0.08

Answer: (C)

Tight control of film densitometry readings is essential for consistent processor performance. When evaluating a processor densitometrically, you look at three values: base plus fog, mid-density, and density difference. The base plus fog reflects the minimum density from the base stock and any fog; it should stay very stable because it’s not driven by image content and is most sensitive to processing conditions. Keeping this variation small, such as ±0.05, helps reveal drift from the base material or cleaning issues.

Mid-density represents a mid-tone density and is influenced more by processing conditions and exposure than the base+fog value. Allowing a moderate variation, ±0.10, accommodates normal day-to-day fluctuations while still detecting meaningful changes in processor performance.

Density difference measures the contrast between densities at different steps. It should also be tightly controlled to ensure the processor maintains consistent contrast, and a tolerance of ±0.10 provides that balance between stability and practicality.

Other options that loosen the mid-density or density difference tolerances (or tighten the base+fog tolerance excessively) risk masking processor drift or demanding impractical precision, so the combination of Base+Fog within ±0.05, Mid-Density within ±0.10, and Density Difference within ±0.10 is the best fit.