Film_speed

qas: question: What does the film's quantum efficiency limit? 
answers: text: sensitivity
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question: What speed of film is produced by insensitive film? 
answers: text: slow film
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question: What leads to lower quality images?
answers: text: reduction of exposure
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question: What types of film are considered fast films?
answers: text: Highly sensitive films
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question: What effect does highly sensitive film have on images?
answers: text: reduced image quality
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question: What does insensitive film with a faster speed index need?
is_impossible: yes

question: What does a sensitive film more of?
is_impossible: yes

question: How is digital photography different from film?
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question: Higher sensitivity leads to greater what?
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question: What does a grainier image limit?
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question: With what type of metering can the Standard Output Sensitivity not be used?
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question: What speed of film is the Ilford Delta 3200?
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question: What scientist suggested comparing the systems?
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context: 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.

qas: question: What consists of 25 pigmented squares touching a plate below a phosphorescent tablet under the light of a burning Magnesium ribbon?
answers: text: The Warnerke Standard Sensitometer
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question: What do degrees Warnerke measure?
answers: text: The speed of the emulsion
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question: How much speed is associated with each degree Warnerke?
answers: text: an increase of 1/3 in speed
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question: What were usual ranges of Warnerke speeds? 
answers: text: between 10° and 25° Warnerke
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question: What does the last exposed number on the plate represent? 
answers: text: 'degrees' Warnerke
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question: The Warnerke Standard Sensitometer has 25 opaque what?
is_impossible: yes

question: What measures the number of pigmented squares on the photographic plate?
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question: Degrees Warneke represented the first what?
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question: What was the range of the number of squares in a Sensitometer?
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question: Each number represented a decrease of what?
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question: What were ANSI values often called in the beginning?
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question: What is film speed combined with to produce optical density?
is_impossible: yes

question: How many techniques are available because of ISO 12232:2006?
is_impossible: yes
context: 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.

qas: question: Who created the Scheinergrade system? 
answers: text: the German astronomer Julius Scheiner
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question: What is the Scheinergrade system used for?
answers: text: comparing the speeds of plates used for astronomical photography
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question: What do degrees Scheiner indicate?
answers: text: the speed of a plate
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question: What is the range of Scheiner speeds?
answers: text: from 1° Sch. to 20° Sch
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question: Approximately how many degrees indicate double the sensitivity? 
answers: text: an increment of 3° Sch
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question: What was the second use of the Scheinergrade system?
is_impossible: yes

question: What did an increment of 1 degree Sch. correspond to?
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question: What was 20 degrees Sch. indicative of?
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question: What measured the visible darkening of a developing photograph?
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question: When did the Scheinergrade system become outdated?
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question: When should the noise-based speed be used?
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question: What option does the Recommended Exposure Index give manufacturers? 
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question: What standards did DIN abandon?
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context: The Scheinergrade (Sch.) system was devised by the German astronomer Julius Scheiner (1858–1913) in 1894 originally as a method of comparing the speeds of plates used for astronomical photography. Scheiner's system rated the speed of a plate by the least exposure to produce a visible darkening upon development. Speed was expressed in degrees Scheiner, originally ranging from 1° Sch. to 20° Sch., where an increment of 19° Sch. corresponded to a hundredfold increase in sensitivity, which meant that an increment of 3° Sch. came close to a doubling of sensitivity.

qas: question: Who developed a device that improved on the shortcomings of Scheiner's invention?
answers: text: Austrian scientist Josef Maria Eder (1855–1944) and Flemish-born botanist Walter Hecht (de)
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question: What did the Eder-Hecht device measure?
answers: text: emulsion speeds
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question: What method did manufacturers use much of the time to compare film speeds?
answers: text: comparing with competing products
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question: What type of measurement methods began to proliferate?
answers: text: modified semi-Scheiner-based systems
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question: What eliminated comparability?
answers: text: modified semi-Scheiner-based systems
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question: Who caused the shortcomings in the Scheiner invention?
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question: What device allowed manufacturers to reliably determine speed?
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question: What was revised to a measure a tighter range?
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question: What made comparability a more common option?
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question: What scientist suggested comparing the systems?
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question: What does the higher speed do for the images produced?
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question: What is the range of Scheiner speeds?
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question: What safety factors were done away with beginning with the modifications to the standards?
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context: The system was later extended to cover larger ranges and some of its practical shortcomings were addressed by the Austrian scientist Josef Maria Eder (1855–1944) and Flemish-born botanist Walter Hecht (de) (1896–1960), (who, in 1919/1920, jointly developed their Eder–Hecht neutral wedge sensitometer measuring emulsion speeds in Eder–Hecht grades). Still, it remained difficult for manufactures to reliably determine film speeds, often only by comparing with competing products, so that an increasing number of modified semi-Scheiner-based systems started to spread, which no longer followed Scheiner's original procedures and thereby defeated the idea of comparability.

qas: question: When was the DIN system established? 
answers: text: January 1934
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question: Who created the DIN system?
answers: text: Deutsches Institut für Normung
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question: What was proposed at the VIII International Congress of Photography?
answers: text: a standardized method of sensitometry
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question: Who presented the idea that grew into the DIN?
answers: text: Robert Luther (de) (1868–1945) and Emanuel Goldberg (1881–1970)
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question: Where was the VIII International Congress of Photography held?
answers: text: Dresden
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question: When were the drafts by Deutscher Normenausschuß für Phototechnik made?
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question: What was the abbreviation for the Deutscher Normenausschuß für Phototechnik drafts?
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question: When was Deutsche Gesellschaft für photographische Forschung founded?
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question: Where was Emanuel Goldberg from?
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question: Who founded the VIII. International Congress of Photography?
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question: What is a definition of signal-to-noise ratio?
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question: How many techniques are available because of ISO 12232:2006?
is_impossible: yes

question: What is another name for film speed?
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context: The DIN system, officially DIN standard 4512 by Deutsches Institut für Normung (but still named Deutscher Normenausschuß (DNA) at this time), was published in January 1934. It grew out of drafts for a standardized method of sensitometry put forward by Deutscher Normenausschuß für Phototechnik as proposed by the committee for sensitometry of the Deutsche Gesellschaft für photographische Forschung since 1930 and presented by Robert Luther (de) (1868–1945) and Emanuel Goldberg (1881–1970) at the influential VIII. International Congress of Photography (German: Internationaler Kongreß für wissenschaftliche und angewandte Photographie) held in Dresden from August 3 to 8, 1931.

qas: question: What unit was used in the DIN to express speeds? 
answers: text: degrees
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question: How was sensitivity expressed at first in the DIN system?
answers: text: as a fraction with 'tenths' (for example "18/10° DIN")
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question: When did the degree symbol fall out of use in the DIN system?
answers: text: with DIN 4512:1961-10
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question: Why did the definition of film speeds change considerably?
answers: text: to accommodate then-recent changes in the American ASA PH2.5-1960 standard
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question: What happened to film speeds of black-and-white negative film?
answers: text: would become doubled
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question: What replaced the American ASA PH2.5-1960 standard?
is_impossible: yes

question: What system reintroduced the degree symbol?
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question: What American standard abandoned the tenths method?
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question: With emulsion changes, what did 18° DIN become?
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question: What happened to film speeds after the introduction of the DIN 4512:1957-11?
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question: What is film speed combined with to produce optical density?
is_impossible: yes

question: What do choices do camera designs not offer?
is_impossible: yes

question: What medal did Edward Faraday Weston win?
is_impossible: yes
context: As in the Scheiner system, speeds were expressed in 'degrees'. Originally the sensitivity was written as a fraction with 'tenths' (for example "18/10° DIN"), where the resultant value 1.8 represented the relative base 10 logarithm of the speed. 'Tenths' were later abandoned with DIN 4512:1957-11, and the example above would be written as "18° DIN". The degree symbol was finally dropped with DIN 4512:1961-10. This revision also saw significant changes in the definition of film speeds in order to accommodate then-recent changes in the American ASA PH2.5-1960 standard, so that film speeds of black-and-white negative film effectively would become doubled, that is, a film previously marked as "18° DIN" would now be labeled as "21 DIN" without emulsion changes.

qas: question: What took the place of the German DIN 4512 system?
answers: text: ISO 6:1974, ISO 2240:1982, and ISO 5800:1979
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question: How is sensitivity shown in the ISO systems?
answers: text: in linear and logarithmic form as "ISO 100/21°"
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question: What standards did the DIN begin to use?
answers: text: ISO standards
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question: When were the ISO standards first adopted?
answers: text: in the 1980s
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question: When were the last ISO standards adopted? 
answers: text: July 2002
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question: What did the German DIN 4512 supersede?
is_impossible: yes

question: What German system wrote in a linear and logarithmic form?
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question: What standards did DIN abandon?
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question: When did the ISO adopt the DIN standards?
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question: When did DIN 4512-5:1990-11 replace DIN ISO 5800:1998-06?
is_impossible: yes

question: What is the only technique that can be used when multi-zone metering is used?
is_impossible: yes

question: What is another speed that can also be reported by the camera?
is_impossible: yes

question: What does the amplifier prevent from increasing?
is_impossible: yes
context: On an international level the German DIN 4512 system has been effectively superseded in the 1980s by ISO 6:1974, ISO 2240:1982, and ISO 5800:1979 where the same sensitivity is written in linear and logarithmic form as "ISO 100/21°" (now again with degree symbol). These ISO standards were subsequently adopted by DIN as well. Finally, the latest DIN 4512 revisions were replaced by corresponding ISO standards, DIN 4512-1:1993-05 by DIN ISO 6:1996-02 in September 2000, DIN 4512-4:1985-08 by DIN ISO 2240:1998-06 and DIN 4512-5:1990-11 by DIN ISO 5800:1998-06 both in July 2002.

qas: question: What system was used previous to the ASA system?
answers: text: the system of Weston film speed ratings
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question: Who devised the Weston film speed ratings? 
answers: text: Edward Faraday Weston (1878–1971) and his father Dr. Edward Weston (1850–1936)
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question: What company did Dr. Edward Weston start? 
answers: text: the US-based Weston Electrical Instrument Corporation
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question: When was the Weston model 617 created?
answers: text: August 1932
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question: Who is credited with creating the film and meter system?
answers: text: William Nelson Goodwin, Jr.
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question: Who introduced the ASA system?
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question: When was the ASA system introduced?
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question: When was William Nelson Goodwin Jr. born?
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question: What medal did Edward Faraday Weston win?
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question: What did Howard N. Potts invent in 1932?
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question: What is the upper limit of saturation determined by?
is_impossible: yes

question: What is film speed combined with to produce optical density?
is_impossible: yes

question: What can too much exposure lead to?
is_impossible: yes
context: Before the advent of the ASA system, the system of Weston film speed ratings was introduced by Edward Faraday Weston (1878–1971) and his father Dr. Edward Weston (1850–1936), a British-born electrical engineer, industrialist and founder of the US-based Weston Electrical Instrument Corporation, with the Weston model 617, one of the earliest photo-electric exposure meters, in August 1932. The meter and film rating system were invented by William Nelson Goodwin, Jr., who worked for them and later received a Howard N. Potts Medal for his contributions to engineering.

qas: question: Which cameras were first of their type to adopt the ASA scale?
answers: text: The Weston Cadet (model 852 introduced in 1949), Direct Reading (model 853 introduced 1954) and Master III (models 737 and S141.3 introduced in 1956)
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question: What were updated Weston values based on?
answers: text: the ASA system
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question: How were Weston values changed to ASA values?
answers: text: by subtracting 1/3 exposure stop
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question: Beginning with which year was the Weston to ASA conversion not necessary?
answers: text: 1956
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question: Until what year did other models use the original Weston scale?
answers: text: 1955
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question: Which two models were introduced in 1949?
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question: When did models move back to the Weston scale?
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question: What was added to convert Weston values to the older meters?
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question: What was necessary on meters manufactured after 1956?
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question: When was the ASA scale established?
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question: When was the SOS technique applied to raw images?
is_impossible: yes

question: What scientist suggested comparing the systems?
is_impossible: yes

question: Who is credited with creating the film and meter system?
is_impossible: yes
context: The Weston Cadet (model 852 introduced in 1949), Direct Reading (model 853 introduced 1954) and Master III (models 737 and S141.3 introduced in 1956) were the first in their line of exposure meters to switch and utilize the meanwhile established ASA scale instead. Other models used the original Weston scale up until ca. 1955. The company continued to publish Weston film ratings after 1955, but while their recommended values often differed slightly from the ASA film speeds found on film boxes, these newer Weston values were based on the ASA system and had to be converted for use with older Weston meters by subtracting 1/3 exposure stop as per Weston's recommendation. Vice versa, "old" Weston film speed ratings could be converted into "new" Westons and the ASA scale by adding the same amount, that is, a film rating of 100 Weston (up to 1955) corresponded with 125 ASA (as per ASA PH2.5-1954 and before). This conversion was not necessary on Weston meters manufactured and Weston film ratings published since 1956 due to their inherent use of the ASA system; however the changes of the ASA PH2.5-1960 revision may be taken into account when comparing with newer ASA or ISO values.

qas: question: Which company adopted the ASA scale in 1946?
answers: text: General Electric
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question: Beginning what year were cameras built with the ASA meter?
answers: text: 1946
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question: How did older models convert to ASA scale?
answers: text: replaceable hoods with ASA scales
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question: How was the ASA scale shown on models built after 1946?
answers: text: labeled "Exposure Index"
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question: What were recommended film values lined up with after 1946?
answers: text: they were now aligned to the ASA scale
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question: What company stopped using ASA in 1946?
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question: When were the DW-48 and DW-49 models made?
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question: What were models pre-1946 labeled with?
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question: Who refused to create replaceable hoods with ASA scales?
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question: What did the recommended film values no longer follow after 1946?
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question: How is the exposure of film changed?
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question: Who is credited with creating the film and meter system?
is_impossible: yes

question: What system uses ratios?
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context: General Electric switched to use the ASA scale in 1946. Meters manufactured since February 1946 were equipped with the ASA scale (labeled "Exposure Index") already. For some of the older meters with scales in "Film Speed" or "Film Value" (e.g. models DW-48, DW-49 as well as early DW-58 and GW-68 variants), replaceable hoods with ASA scales were available from the manufacturer. The company continued to publish recommended film values after that date, however, they were now aligned to the ASA scale.

qas: question: Who pioneered research that led to the new ANSI values?
answers: text: Loyd Ancile Jones
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question: What standards were the ANSI developed from?
answers: text: Weston film speed ratings and General Electric film values
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question: What types of film did the ANSI measure?
answers: text: black-and-white negative films
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question: When did the ANSI define its new measure?
answers: text: 1943
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question: What were ANSI values often called in the beginning?
answers: text: American standard speed numbers or ASA exposure-index numbers
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question: Who did research for General Electric?
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question: What was Kodak renamed as?
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question: What were the Weston Film speed ratings inspired by?
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question: When did Jones publish his research?
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question: When was ASA PH2.5-1954 released?
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question: What is a definition of signal-to-noise ratio?
is_impossible: yes

question: How can the saturation speed be increased?
is_impossible: yes

question: What is the upper limit of saturation determined by?
is_impossible: yes
context: Based on earlier research work by Loyd Ancile Jones (1884–1954) of Kodak and inspired by the systems of Weston film speed ratings and General Electric film values, the American Standards Association (now named ANSI) defined a new method to determine and specify film speeds of black-and-white negative films in 1943. ASA Z38.2.1-1943 was revised in 1946 and 1947 before the standard grew into ASA PH2.5-1954. Originally, ASA values were frequently referred to as American standard speed numbers or ASA exposure-index numbers. (See also: Exposure Index (EI).)

qas: question: In what year were big changes made to the ANSI?
answers: text: 1960
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question: What did the 1960 changes to film speed measures lead to?
answers: text: effectively doubling the nominal speed of many black-and-white negative films
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question: Which other system were these changes applied to?
answers: text: the DIN system
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question: In what year was the BS system modified?
answers: text: 1963
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question: What safety factors were done away with beginning with the modifications to the standards?
answers: text: safety factors against under-exposure
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question: When were new safety factors put in place?
is_impossible: yes

question: The nominal speed of what films were halved by abandoning safety factors?
is_impossible: yes

question: A 400 ASA became what after 1960?
is_impossible: yes

question: When were changes applied to the DIN system?
is_impossible: yes

question: The Ilford HP3 changes were applied to what in the following years?
is_impossible: yes

question: What medal did Edward Faraday Weston win?
is_impossible: yes

question: What does insensitive film with a faster speed index need?
is_impossible: yes

question: What scientist suggested comparing the systems?
is_impossible: yes
context: The ASA standard underwent a major revision in 1960 with ASA PH2.5-1960, when the method to determine film speed was refined and previously applied safety factors against under-exposure were abandoned, effectively doubling the nominal speed of many black-and-white negative films. For example, an Ilford HP3 that had been rated at 200 ASA before 1960 was labeled 400 ASA afterwards without any change to the emulsion. Similar changes were applied to the DIN system with DIN 4512:1961-10 and the BS system with BS 1380:1963 in the following years.

qas: question: What is the plot from which film speed is derived called?
answers: text: the D–log H curve or Hurter–Driffield curve
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question: How many regions does the Hurter-Driffield curve have?
answers: text: five
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question: What is plotted in the Hurter-Driffield curve?
answers: text: a plot of optical density vs. log of exposure for the film
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question: What is denoted when the specified contrast condition is met?
answers: text: The exposure Hm, in lux-s
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question: What are the five regions of the Hurter-Driffield curve?
answers: text: the base + fog, the toe, the linear region, the shoulder, and the overexposed region
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question: What is film speed combined with to produce optical density?
is_impossible: yes

question: What is a plot of film speed vs. log of exposure called?
is_impossible: yes

question: How many speed points are there in a black and white film?
is_impossible: yes

question: What is the point at which density is 0.1 less than the base + fog?
is_impossible: yes

question: What is the ISO arithmetic speed?
is_impossible: yes

question: What does the amplifier prevent from increasing?
is_impossible: yes

question: Until what year did other models use the original Weston scale?
is_impossible: yes

question: 3200 is the true ISO of what film?
is_impossible: yes
context: Film speed is found from a plot of optical density vs. log of exposure for the film, known as the D–log H curve or Hurter–Driffield curve. There typically are five regions in the curve: the base + fog, the toe, the linear region, the shoulder, and the overexposed region. For black-and-white negative film, the “speed point” m is the point on the curve where density exceeds the base + fog density by 0.1 when the negative is developed so that a point n where the log of exposure is 1.3 units greater than the exposure at point m has a density 0.8 greater than the density at point m. The exposure Hm, in lux-s, is that for point m when the specified contrast condition is satisfied. The ISO arithmetic speed is determined from:

qas: question: What is the effective f-number proportional to?
answers: text: the ratio between the lens focal length and aperture diameter
is_impossible: no

question: What is used to discover the right exposure parameters?
answers: text: Film speed
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question: What variables help the photographer produce the desired effect?
answers: text: lighting, film speed, f-number (aperture size), and shutter speed (exposure time)
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question: A lens with a setting of f/1.4 lets how much to hit the focal plane compared with a setting of f/2?
answers: text: twice as much
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question: In the APEX system, the increment that doubles the exposure is called what?
answers: text: "stop"
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question: What are appropriate exposure parameters used to find?
is_impossible: yes

question: What is another name for film speed?
is_impossible: yes

question: What system uses ratios?
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question: The ratio between the diameter and square root of the aperture is called what?
is_impossible: yes

question: How much does light does an f/2 let in as compared to an f/4?
is_impossible: yes

question: What, besides a faster processor, prevents processing from happening when a photo is taken?
is_impossible: yes

question: When was the SOS technique applied to raw images?
is_impossible: yes

question: How are ways of finding an emulsion's sensitivity possible?
is_impossible: yes
context: Film speed is used in the exposure equations to find the appropriate exposure parameters. Four variables are available to the photographer to obtain the desired effect: lighting, film speed, f-number (aperture size), and shutter speed (exposure time). The equation may be expressed as ratios, or, by taking the logarithm (base 2) of both sides, by addition, using the APEX system, in which every increment of 1 is a doubling of exposure; this increment is commonly known as a "stop". The effective f-number is proportional to the ratio between the lens focal length and aperture diameter, the diameter itself being proportional to the square root of the aperture area. Thus, a lens set to f/1.4 allows twice as much light to strike the focal plane as a lens set to f/2. Therefore, each f-number factor of the square root of two (approximately 1.4) is also a stop, so lenses are typically marked in that progression: f/1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, etc.

qas: question: What determines the effect on the emulsion after exposure?
answers: text: the amount of light energy that reaches the film
is_impossible: no

question: In what range of exposures does reciprocity usually work?
answers: text: between 1/1000 second to 1/2 second
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question: How is the exposure of film changed?
answers: text: by varying the camera's shutter speed and aperture
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question: How are ways of finding an emulsion's sensitivity possible?
answers: text: because reciprocity holds
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question: What happens outside the 1/1000 second to 1/second exposure range?
answers: text: reciprocity failure
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question: What determines the amount of light energy that reaches the film?
is_impossible: yes

question: Multiplying the brightness of a light by a factor and decreasing the exposure by the same factor causes what to change?
is_impossible: yes

question: How is the brightness of a light changed?
is_impossible: yes

question: Reciprocity only works outside of what ranges?
is_impossible: yes

question: Reciprocity holds because of what system?
is_impossible: yes

question: Who is credited with creating the film and meter system?
is_impossible: yes

question: Who provides the exposure index rating?
is_impossible: yes

question: What type of films are Ilford Delta 3200 and Kodak T-MAX P3200?
is_impossible: yes
context: Upon exposure, the amount of light energy that reaches the film determines the effect upon the emulsion. If the brightness of the light is multiplied by a factor and the exposure of the film decreased by the same factor by varying the camera's shutter speed and aperture, so that the energy received is the same, the film will be developed to the same density. This rule is called reciprocity. The systems for determining the sensitivity for an emulsion are possible because reciprocity holds. In practice, reciprocity works reasonably well for normal photographic films for the range of exposures between 1/1000 second to 1/2 second. However, this relationship breaks down outside these limits, a phenomenon known as reciprocity failure.

qas: question: What are two examples of films that are marketed with speeds above their true ISO speed?
answers: text: Ilford Delta 3200 and Kodak T-MAX P3200
is_impossible: no

question: What speed of film is the Ilford Delta 3200?
answers: text: ISO 1000
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question: Which two companies produced E6 films meant for "pushing"?
answers: text: Kodak and Fuji
is_impossible: no

question: What is the base speed of Ektachrome P800/1600 and Fujichrome P1600?
answers: text: ISO 400
is_impossible: no

question: What type of films are Ilford Delta 3200 and Kodak T-MAX P3200?
answers: text: high-speed black-and-white films
is_impossible: no

question: What cameras have speeds above what they are marketed as?
is_impossible: yes

question: 3200 is the true ISO of what film?
is_impossible: yes

question: What is the true speed of the Kodak T-MAX P3200 according to the data sheet?
is_impossible: yes

question: What is the Delta 3200 designed for? 
is_impossible: yes

question: Ilford Delta and Fuji marketed what kind of film?
is_impossible: yes

question: What do choices do camera designs not offer?
is_impossible: yes

question: What type of films are Ilford Delta 3200 and Kodak T-MAX P3200?
is_impossible: yes

question: What did the Eder-Hecht device measure?
is_impossible: yes
context: Some high-speed black-and-white films, such as Ilford Delta 3200 and Kodak T-MAX P3200, are marketed with film speeds in excess of their true ISO speed as determined using the ISO testing method. For example, the Ilford product is actually an ISO 1000 film, according to its data sheet. The manufacturers do not indicate that the 3200 number is an ISO rating on their packaging. Kodak and Fuji also marketed E6 films designed for pushing (hence the "P" prefix), such as Ektachrome P800/1600 and Fujichrome P1600, both with a base speed of ISO 400.

qas: question: What is another name for an exposure index rating?
answers: text: ISO setting
is_impossible: no

question: How do some camera designs give some EI choices?
answers: text: by adjusting the sensor's signal gain in the digital realm
is_impossible: no

question: Who provides the exposure index rating?
answers: text: the manufacturer
is_impossible: no

question: What are digital photo cameras also called?
answers: text: digital still cameras
is_impossible: no

question: What is an sRGB image file commonly called?
is_impossible: yes

question: The lightness of an sRGB file is designed to be different from what?
is_impossible: yes

question: What is adjusted prior to conversion to analog?
is_impossible: yes

question: What do choices do camera designs not offer?
is_impossible: yes

question: What does the choice of lightness parameters prevent?
is_impossible: yes

question: What was retracted in the 2006 standards?
is_impossible: yes

question: What measured the visible darkening of a developing photograph?
is_impossible: yes

question: What scientist suggested comparing the systems?
is_impossible: yes
context: For digital photo cameras ("digital still cameras"), an exposure index (EI) rating—commonly called ISO setting—is specified by the manufacturer such that the sRGB image files produced by the camera will have a lightness similar to what would be obtained with film of the same EI rating at the same exposure. The usual design is that the camera's parameters for interpreting the sensor data values into sRGB values are fixed, and a number of different EI choices are accommodated by varying the sensor's signal gain in the analog realm, prior to conversion to digital. Some camera designs provide at least some EI choices by adjusting the sensor's signal gain in the digital realm. A few camera designs also provide EI adjustment through a choice of lightness parameters for the interpretation of sensor data values into sRGB; this variation allows different tradeoffs between the range of highlights that can be captured and the amount of noise introduced into the shadow areas of the photo.

qas: question: What types of cameras have proven to be much more sensitive to light than film?
answers: text: Digital cameras
is_impossible: no

question: What ISO equivalent speeds can digital cameras obtain?
answers: text: 409,600
is_impossible: no

question: What is responsible for these vast increases in speed?
answers: text: Faster processors, as well as advances in software noise reduction techniques
is_impossible: no

question: What is one thing that limited speeds of older digital hardware?
answers: text: prohibitively time consuming to process
is_impossible: no

question: What does the higher speed do for the images produced?
answers: text: a higher level of refinement
is_impossible: no

question: How has film surpassed digital cameras?
is_impossible: yes

question: What is the highest ISO speed a film camera can reach?
is_impossible: yes

question: What, besides a faster processor, prevents processing from happening when a photo is taken?
is_impossible: yes

question: What could earlier generations of digital cameras store?
is_impossible: yes

question: Which generation of cameras are capable of storing higher refined images?
is_impossible: yes

question: How are the two ratios found?
is_impossible: yes

question: What is an sRGB image file commonly called?
is_impossible: yes

question: What is the noise-based speed?
is_impossible: yes
context: Digital cameras have far surpassed film in terms of sensitivity to light, with ISO equivalent speeds of up to 409,600, a number that is unfathomable in the realm of conventional film photography. Faster processors, as well as advances in software noise reduction techniques allow this type of processing to be executed the moment the photo is captured, allowing photographers to store images that have a higher level of refinement and would have been prohibitively time consuming to process with earlier generations of digital camera hardware.

qas: question: How many techniques are available because of ISO 12232:2006?
answers: text: five
is_impossible: no

question: What techniques did CIPA DC-004 provide?
answers: text: two new techniques allowing for measurement of JPEG output files
is_impossible: no

question: What factors affect the exposure index rating?
answers: text: the sensor sensitivity, the sensor noise, and the appearance of the resulting image
is_impossible: no

question: What does the standard of ISO 12232:2006 specify?
answers: text: the measurement of light sensitivity of the entire digital camera system and not of individual components
is_impossible: no

question: In what year did Kodak start using a different way of characterizing two sensors?
answers: text: 2001
is_impossible: no

question: When was ISO 12232:2006 made public?
is_impossible: yes

question: How many JPEG techniques were introduced in 1998?
is_impossible: yes

question: What are the three techniques that affect ISO?
is_impossible: yes

question: How many techniques depend on sensor sensitivity?
is_impossible: yes

question: When did Kodak stop using variations of sensitivity?
is_impossible: yes

question: What did the Eder-Hecht device measure?
is_impossible: yes

question: What method did manufacturers use much of the time to compare film speeds?
is_impossible: yes

question: What standards did the DIN begin to use?
is_impossible: yes
context: The ISO standard ISO 12232:2006 gives digital still camera manufacturers a choice of five different techniques for determining the exposure index rating at each sensitivity setting provided by a particular camera model. Three of the techniques in ISO 12232:2006 are carried over from the 1998 version of the standard, while two new techniques allowing for measurement of JPEG output files are introduced from CIPA DC-004. Depending on the technique selected, the exposure index rating can depend on the sensor sensitivity, the sensor noise, and the appearance of the resulting image. The standard specifies the measurement of light sensitivity of the entire digital camera system and not of individual components such as digital sensors, although Kodak has reported using a variation to characterize the sensitivity of two of their sensors in 2001.

qas: question: What option does the Recommended Exposure Index give manufacturers? 
answers: text: to specify a camera model’s EI choices arbitrarily
is_impossible: no

question: What is another name for multi-zone metering?
answers: text: pattern metering
is_impossible: no

question: What distinction does the Recommended Exposure Index have?
answers: text: the only technique available under the standard for output formats that are not in the sRGB color space
is_impossible: no

question: When was the Recommended Exposure Index introduced?
answers: text: 2006
is_impossible: no

question: What is the only technique that can be used when multi-zone metering is used?
answers: text: Recommended Exposure Index (REI) technique
is_impossible: no

question: What standardized EI choices?
is_impossible: yes

question: When was multi-zone metering introduced?
is_impossible: yes

question: REI and what are the only techniques available under standard outputs?
is_impossible: yes

question: What was retracted in the 2006 standards?
is_impossible: yes

question: Who created the 2006 standard?
is_impossible: yes

question: What was revised to a measure a tighter range?
is_impossible: yes

question: What does the amplifier prevent from increasing?
is_impossible: yes

question: What standards changed what Japanese camera makers have to specify?
is_impossible: yes
context: The Recommended Exposure Index (REI) technique, new in the 2006 version of the standard, allows the manufacturer to specify a camera model’s EI choices arbitrarily. The choices are based solely on the manufacturer’s opinion of what EI values produce well-exposed sRGB images at the various sensor sensitivity settings. This is the only technique available under the standard for output formats that are not in the sRGB color space. This is also the only technique available under the standard when multi-zone metering (also called pattern metering) is used.

qas: question: What year was the Standard Output Sensitivity technique introduced?
answers: text: 2006
is_impossible: no

question: What does the Standard Output Sensitivity technique apply to?
answers: text: sRGB images—typically JPEG
is_impossible: no

question: What is the output level measured in?
answers: text: the sRGB output from the camera
is_impossible: no

question: With what type of metering can the Standard Output Sensitivity not be used?
answers: text: multi-zone metering
is_impossible: no

question: With what standard is the automatic exposure control system calibrated?
answers: text: ISO 2721
is_impossible: no

question: What technique was removed in the 2006 standards?
is_impossible: yes

question: When exposure is not automatically controlled, what is the gray set at?
is_impossible: yes

question: How are files in raw measured?
is_impossible: yes

question: Multi-zone metering uses what ISO calibration?
is_impossible: yes

question: When was the SOS technique applied to raw images?
is_impossible: yes

question: When was ASA PH2.5-1954 released?
is_impossible: yes

question: Why is the factor of 78 avoided?
is_impossible: yes

question: Ilford Delta and Fuji marketed what kind of film?
is_impossible: yes
context: The Standard Output Sensitivity (SOS) technique, also new in the 2006 version of the standard, effectively specifies that the average level in the sRGB image must be 18% gray plus or minus 1/3 stop when the exposure is controlled by an automatic exposure control system calibrated per ISO 2721 and set to the EI with no exposure compensation. Because the output level is measured in the sRGB output from the camera, it is only applicable to sRGB images—typically JPEG—and not to output files in raw image format. It is not applicable when multi-zone metering is used.

qas: question: Which methods are required by CIPA DC-004?
answers: text: REI or SOS techniques
is_impossible: no

question: In what year did the three EI techniques from ISO 12232:1998 largely stop being used?
answers: text: approximately 2007 and later
is_impossible: no

question: With what cameras can earlier techniques not be used?
answers: text: cameras that produce images only in JPEG format
is_impossible: no

question: What nation's cameras does the CIPA DC-004 apply to?
answers: text: Japanese
is_impossible: no

question: What does the DC-008 change?
answers: text: the Exif specification
is_impossible: no

question: How many techniques are widely used in new camera models?
is_impossible: yes

question: When was the CIPA DC-004 standard released?
is_impossible: yes

question: Which manufacturers are exempt from CIPA DC-004?
is_impossible: yes

question: After 2007, newer camera models started using what techniques again?
is_impossible: yes

question: The three EI techniques have to be used on cameras that only capture in what format?
is_impossible: yes

question: What was the abbreviation for the Deutscher Normenausschuß für Phototechnik drafts?
is_impossible: yes

question: When did the degree symbol fall out of use in the DIN system?
is_impossible: yes

question: What made comparability a more common option?
is_impossible: yes
context: The CIPA DC-004 standard requires that Japanese manufacturers of digital still cameras use either the REI or SOS techniques, and DC-008 updates the Exif specification to differentiate between these values. Consequently, the three EI techniques carried over from ISO 12232:1998 are not widely used in recent camera models (approximately 2007 and later). As those earlier techniques did not allow for measurement from images produced with lossy compression, they cannot be used at all on cameras that produce images only in JPEG format.

qas: question: What does the sensor usually determine?
answers: text: lower limit of the saturation speed
is_impossible: no

question: How can the saturation speed be increased?
answers: text: with the gain of the amplifier between the sensor and the analog-to-digital converter
is_impossible: no

question: What is indicated by the factor √2?
answers: text: there is half a stop of headroom to deal with specular reflections that would appear brighter than a 100% reflecting white surface
is_impossible: no

question: What can too much exposure lead to?
answers: text: clipped or bloomed camera output
is_impossible: no

question: The lower limit of saturation speed leads to what?
is_impossible: yes

question: What does the amplifier prevent from increasing?
is_impossible: yes

question: Why is the factor of 78 avoided?
is_impossible: yes

question: A grey level of 12.7 results in what saturation?
is_impossible: yes

question: What is the upper limit of saturation determined by?
is_impossible: yes

question: How was the ASA scale shown on models built after 1946?
is_impossible: yes

question: What is an sRGB image file commonly called?
is_impossible: yes

question: The ISO 12232 requires manufacturures to specify what about a sensitivity rating?
is_impossible: yes
context: where  is the maximum possible exposure that does not lead to a clipped or bloomed camera output. Typically, the lower limit of the saturation speed is determined by the sensor itself, but with the gain of the amplifier between the sensor and the analog-to-digital converter, the saturation speed can be increased. The factor 78 is chosen such that exposure settings based on a standard light meter and an 18-percent reflective surface will result in an image with a grey level of 18%/√2 = 12.7% of saturation. The factor √2 indicates that there is half a stop of headroom to deal with specular reflections that would appear brighter than a 100% reflecting white surface.

qas: question: Which ratios are employed to calculate noise-based speed?
answers: text: the 40:1 ("excellent image quality") and the 10:1 ("acceptable image quality") ratio
is_impossible: no

question: What is the noise-based speed?
answers: text: the exposure that will lead to a given signal-to-noise ratio on individual pixels
is_impossible: no

question: How are the two ratios found?
answers: text: subjectively determined based on a resolution of 70 pixels per cm (178 DPI) when viewed at 25 cm (9.8 inch) distance
is_impossible: no

question: What is a definition of signal-to-noise ratio?
answers: text: the standard deviation of a weighted average of the luminance and color of individual pixels
is_impossible: no

question: What factors influence the noise-based speed?
answers: text: the properties of the sensor and somewhat affected by the noise in the electronic gain and AD converter
is_impossible: no

question: Which ratio was subjectively determined?
is_impossible: yes

question: What are the individual pixels defined by?
is_impossible: yes

question: What is the signal-to-noise ration?
is_impossible: yes

question: How many pixels are in a 40:1 ratio image?
is_impossible: yes

question: The weighted average of the luminance and the noise in the electronic gain is defined as what?
is_impossible: yes

question: When was Deutsche Gesellschaft für photographische Forschung founded?
is_impossible: yes

question: With what type of metering can the Standard Output Sensitivity not be used?
is_impossible: yes

question: What is film speed combined with to produce optical density?
is_impossible: yes
context: The noise-based speed is defined as the exposure that will lead to a given signal-to-noise ratio on individual pixels. Two ratios are used, the 40:1 ("excellent image quality") and the 10:1 ("acceptable image quality") ratio. These ratios have been subjectively determined based on a resolution of 70 pixels per cm (178 DPI) when viewed at 25 cm (9.8 inch) distance. The signal-to-noise ratio is defined as the standard deviation of a weighted average of the luminance and color of individual pixels. The noise-based speed is mostly determined by the properties of the sensor and somewhat affected by the noise in the electronic gain and AD converter.

qas: question: When should the noise-based speed be used?
answers: text: the noise-based speed (40:1) is higher than the saturation-based speed
is_impossible: no

question: What is the range for exposure latitude?
answers: text: from the saturation-based speed to the 10:1 noise-based speed
is_impossible: no

question: What is another speed that can also be reported by the camera?
answers: text: SOS-based speed
is_impossible: no

question: Why should noise-based speed be rounded down to a lower standard?
answers: text: exposure according to the lower saturation-based speed would not result in a visibly better image
is_impossible: no

question: What does the standard specify?
answers: text: how speed ratings should be reported by the camera
is_impossible: no

question: A lower saturation-based speed would create a better what?
is_impossible: yes

question: What is the ratio for the saturation-based speed?
is_impossible: yes

question: Is the SOS rounded up or down?
is_impossible: yes

question: How are underexposed images created?
is_impossible: yes

question: Why are saturation-based speeds rounded down?
is_impossible: yes

question: Who caused the shortcomings in the Scheiner invention?
is_impossible: yes

question: When was the SOS technique applied to raw images?
is_impossible: yes

question: When was the ASA system introduced?
is_impossible: yes
context: The standard specifies how speed ratings should be reported by the camera. If the noise-based speed (40:1) is higher than the saturation-based speed, the noise-based speed should be reported, rounded downwards to a standard value (e.g. 200, 250, 320, or 400). The rationale is that exposure according to the lower saturation-based speed would not result in a visibly better image. In addition, an exposure latitude can be specified, ranging from the saturation-based speed to the 10:1 noise-based speed. If the noise-based speed (40:1) is lower than the saturation-based speed, or undefined because of high noise, the saturation-based speed is specified, rounded upwards to a standard value, because using the noise-based speed would lead to overexposed images. The camera may also report the SOS-based speed (explicitly as being an SOS speed), rounded to the nearest standard speed rating.

qas: question: What measures might the user "ISO" setting correspond to?
answers: text: the noise-based speed, saturation-based speed, or the specified output sensitivity, or even some made-up number for marketing purposes
is_impossible: no

question: What did the 1998 version of ISO 12232 not permit?
answers: text: measurement of camera output that had lossy compression
is_impossible: no

question: What types of sensitivity ratings can be specified by a camera?
answers: text: REI or SOS
is_impossible: no

question: What standards changed what Japanese camera makers have to specify?
answers: text: CIPA DC-004
is_impossible: no

question: In what year was CIPA DC-004 introduced?
answers: text: 2006
is_impossible: no

question: Cameras must indicate when the ISO setting refers to what?
is_impossible: yes

question: The 1998 ISO 12232 allowed for what type of compression?
is_impossible: yes

question: What publication affected Japanese digital still cameras in 1998?
is_impossible: yes

question: When was the TIFF file created?
is_impossible: yes

question: The ISO 12232 requires manufacturures to specify what about a sensitivity rating?
is_impossible: yes

question: With what type of metering can the Standard Output Sensitivity not be used?
is_impossible: yes

question: Beginning what year were cameras built with the ASA meter?
is_impossible: yes

question: What can too much exposure lead to?
is_impossible: yes
context: Despite these detailed standard definitions, cameras typically do not clearly indicate whether the user "ISO" setting refers to the noise-based speed, saturation-based speed, or the specified output sensitivity, or even some made-up number for marketing purposes. Because the 1998 version of ISO 12232 did not permit measurement of camera output that had lossy compression, it was not possible to correctly apply any of those measurements to cameras that did not produce sRGB files in an uncompressed format such as TIFF. Following the publication of CIPA DC-004 in 2006, Japanese manufacturers of digital still cameras are required to specify whether a sensitivity rating is REI or SOS.[citation needed]