PhotographyLesson 2 of 2 in the course Exposure

Film Speed and ISO: Measurement, Exposure, and Digital Ratings

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

Save course
Lesson progress
0 / 5

Your progress is kept in this browser only.Sign up to save it

Summary

Film speed describes how sensitive a photographic emulsion is to light. It matters because it affects the exposure needed to make an image and, often, the image’s grain and detail.

Film speed is a measure of a film emulsion’s sensitivity to light. A more sensitive, or faster, emulsion needs less exposure to produce an acceptable image. A less sensitive, or slower, emulsion needs more exposure.

All flashcards

What is sensitometry?
The measurement of how photographic materials respond to controlled exposure and processing.
What does a D–log H curve show?
Optical density plotted against the logarithm of exposure.
How do the arithmetic and logarithmic ISO scales relate?
Doubling the arithmetic value corresponds to an increase of about 3° on the logarithmic scale.
What is exposure index (EI)?
A chosen speed setting for a film and shooting situation that may differ from its measured ISO speed.
What does digital camera ISO represent?
A system-level rating shaped by sensor signal gain and image processing, rather than a property of the sensor alone.

Quiz questions

  1. When arithmetic ISO doubles, how does the corresponding logarithmic ISO value change approximately?Answer: It increases by about 3 degrees.
  2. What happened to many black-and-white negative film ratings under the 1960 ASA revision?Answer: Their nominal ratings effectively doubled without an emulsion change.
  3. What is reciprocity failure in photographic film?Answer: A breakdown in the usual relationship between exposure time and light intensity.
  4. A photographer rates ISO 400 film at EI 800 for a particular shoot. What does EI 800 indicate?Answer: The chosen exposure setting for that film and situation.
  5. Why is digital camera ISO considered a system-level rating?Answer: Sensor gain and image processing both affect how captured light becomes image values.

Based on the Wikipedia article Film speed, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

More in Photography

All Photography lessons
PhotographyRule of Thirds: Composition, History, and Evidence5 flashcards · 5 quiz questions · 4 gamesPlay free →PhotographyPhotographic Flash: Systems, History, Synchronization, and Lighting5 flashcards · 5 quiz questions · 4 gamesPlay free →PhotographyPhotographic Lighting: Portrait Patterns, Natural Light, and Studio Control5 flashcards · 5 quiz questions · 4 gamesPlay free →PhotographyGolden-Hour and Blue-Hour Lighting in Photography5 flashcards · 5 quiz questions · 4 gamesPlay free →PhotographyPhotography: Light Capture, Historical Processes, and Visual Uses5 flashcards · 5 quiz questions · 4 gamesPlay free →PhotographyVisual Composition: Design Elements, Space, and Arrangement5 flashcards · 5 quiz questions · 4 gamesPlay free →