Practice question · Sort into groups
Sort each material by its colour sensitivity.
Groups: Blue-sensitive only · Orthochromatic · Panchromatic
- Total-darkness loaded film
- 1850s wet collodion
- Graded printing paper
- Red-safelight line-copy film
- Variable-grade paper
- Modern film: HP5 Plus, Tri-X
Hints
- Ask in each case what safelight the material tolerates.
- A variable-contrast paper has to see green, or its filters would do nothing.
Show the answer
Blue-sensitive only: 1850s wet collodion, Graded printing paper
Orthochromatic: Variable-grade paper, Red-safelight line-copy film
Panchromatic: Modern film: HP5 Plus, Tri-X, Total-darkness loaded film
Why
The third item explains the whole design of variable-contrast paper: it must respond differently to blue and to green, so it cannot be blue-sensitive only, and it therefore needs a safelight that emits neither. The safelight is a consequence of the sensitisation, not a separate convention.
Practise The Latent Image
The app has 5 more questions on this lesson, and keeps your place in the course. Photography I is free to start.
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