Photography I / Developing the Negative
Practice question · Estimate

A film needs 10 minutes at 20 degrees Celsius. Using the multiplier table, how many minutes does it need at 24 degrees?

Estimate on a scale from 0 minutes (0) to 15 minutes (15).

Hints
  1. Find the multiplier for 24 degrees in the table.
  2. Multiply 10 by 0.72.
Show the answer

7.2 (answers within ±0.5 count)

Why

About 7.2 minutes, or 7 minutes 12 seconds. Four degrees costs nearly thirty per cent of the time, which is why a thermometer checked once at the start of a session and never again is one of the commonest causes of unaccountably dense negatives on a warm afternoon.

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