Which instrument combination is used for darkroom condition testing?

• A. Hygrometer only
• B. Thermometer and hygrometer
• C. Caliper and ruler
• D. Thermometer only

Answer: (C)

Darkroom condition testing focuses on environmental factors that affect film processing, mainly temperature and humidity. Temperature influences chemical activity and development times, while humidity impacts film handling, curl, and static. To reliably assess these conditions, you use a thermometer to measure temperature and a hygrometer to measure humidity. A hygrometer alone doesn’t tell you the temperature, and a thermometer alone misses humidity. Calipers and rulers measure physical dimensions, not environmental conditions, so they aren’t used for this purpose. Combining thermometer and hygrometer gives you the needed two data points to ensure the darkroom environment stays within acceptable limits.