The darkroom should be properly illuminated, with film correctly matched to illumination using a lamp of what wattage range?

• A. 60-75 watt
• B. 7.5 to 15 watt
• C. 2-5 watt
• D. 100-150 watt

Answer: (B)

Safelight intensity must be low enough to prevent fogging of unexposed film while still giving you enough light to handle and inspect it. A lamp in the 7.5 to 15 watt range, typically used with a deep red or amber filter, provides that safe balance. Higher wattages, like 60–75 W or 100–150 W, are bright enough to cause fogging and unwanted exposure of the film. Too little light, as with 2–5 W, makes handling and locating small details difficult. So, the recommended range is 7.5–15 W to keep the film unexposed while you work.