Practice question · Select all that apply
Which are true of the way a black-and-white negative film's ISO speed is determined?
Hints
- Three describe the standard; one puts the measurement in the wrong place.
- The steepest part is where gamma is measured, not speed.
Show the answer
- A. The standard also specifies the development, so the quoted speed assumes it
- B. The speed point is the exposure giving a density of 0.10 above base plus fog
- D. The speed point sits in the shadows, which is why underexposure empties them first
Why
The fourth confuses the two measurements. Speed is fixed low on the toe and contrast is measured on the straight line, which is why the two can be varied almost independently, the basis of the entire zone system.
Practise Film and the Characteristic Curve
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