Relatively insensitive film, with a correspondingly lower speed index, requires more exposure to light to produce the same image density as a more sensitive film, and is thus commonly termed a slow film. Highly sensitive films are correspondingly termed fast films. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality (via coarser film grain or higher image noise of other types). In short, the higher the sensitivity, the grainier the image will be. Ultimately sensitivity is limited by the quantum efficiency of the film or sensor.

The Warnerke Standard Sensitometer consisted of a frame holding an opaque screen with an array of typically 25 numbered, gradually pigmented squares brought into contact with the photographic plate during a timed test exposure under a phosphorescent tablet excited before by the light of a burning Magnesium ribbon. The speed of the emulsion was then expressed in 'degrees' Warnerke (sometimes seen as Warn. or W.) corresponding with the last number visible on the exposed plate after development and fixation. Each number represented an increase of 1/3 in speed, typical plate speeds were between 10 and 25 Warnerke at the time.

1. What is the speed of a insensitive film?
2. What does it require more of?
3. What is another name for it?
4. What is a fast film?
5. What is a sensitive film?
6. So what happens if it has higher sensitivity?
7. How does that do to the image?
8. What causes the image to be grainier?
9. What is sensitivity limited by?
10. What did the Warnerke Standard Sensitometer consist of?
11. What else did it have?
12. What did it connect with?
13. What was the speed expressed in?
14. Was there an abbreviation for it?
15. What did each number represent?
16. An increase of 1/3 represented what?
17. What were typical plate speeds?

Numbered answers:
1. lower speed
2. exposure to light
3. slow film.
4. no
5. fast films
6. reduced image quality
7. via coarser film grain or higher image noise of other types
8. high sensitivity
9. the quantum efficiency of the film or sensor.
10. a frame
11. an opaque screen with an array of typically 25 numbered, gradually pigmented squares
12. a photographic plate during a timed test exposure under a phosphorescent table
13. degrees
14. Warn. or W
15. corresponding with the last number visible on the exposed plate after development and fixation.
16. Each number
17. 10 and 25 Warnerke