praj-17/QA-MCQ-Open-ended huggingface dataset:
Title: Film_speed
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.

question: What does the film's quantum efficiency limit?  

answer: sensitivity

question: What speed of film is produced by insensitive film?  

answer: slow film

question: What leads to lower quality images? 

answer: reduction of exposure

question: What types of film are considered fast films? 

answer: Highly sensitive films

question: What effect does highly sensitive film have on images? 

answer: reduced image quality
Title: Film_speed
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.

question: What consists of 25 pigmented squares touching a plate below a phosphorescent tablet under the light of a burning Magnesium ribbon? 

answer: The Warnerke Standard Sensitometer

question: What do degrees Warnerke measure? 

answer: The speed of the emulsion

question: How much speed is associated with each degree Warnerke? 

answer: an increase of 1/3 in speed

question: What were usual ranges of Warnerke speeds?  

answer: between 10° and 25° Warnerke

question: What does the last exposed number on the plate represent?  

answer: 'degrees' Warnerke
Title: Film_speed
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.

question: Who created the Scheinergrade system?  

answer: the German astronomer Julius Scheiner

question: What is the Scheinergrade system used for? 

answer: comparing the speeds of plates used for astronomical photography

question: What do degrees Scheiner indicate? 

answer: the speed of a plate

question: What is the range of Scheiner speeds? 

answer: from 1° Sch. to 20° Sch

question: Approximately how many degrees indicate double the sensitivity?  

answer: an increment of 3° Sch
Title: Film_speed
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.

question: Who developed a device that improved on the shortcomings of Scheiner's invention? 

answer: Austrian scientist Josef Maria Eder (1855–1944) and Flemish-born botanist Walter Hecht (de)

question: What did the Eder-Hecht device measure? 

answer: emulsion speeds

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

answer: comparing with competing products

question: What type of measurement methods began to proliferate? 

answer: modified semi-Scheiner-based systems

question: What eliminated comparability? 

answer: modified semi-Scheiner-based systems
Title: Film_speed
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.

question: When was the DIN system established?  

answer: January 1934

question: Who created the DIN system? 

answer: Deutsches Institut für Normung

question: What was proposed at the VIII International Congress of Photography? 

answer: a standardized method of sensitometry

question: Who presented the idea that grew into the DIN? 

answer: Robert Luther (de) (1868–1945) and Emanuel Goldberg (1881–1970)

question: Where was the VIII International Congress of Photography held? 

answer: Dresden
Title: Film_speed
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.

question: What unit was used in the DIN to express speeds?  

answer: degrees

question: How was sensitivity expressed at first in the DIN system? 

answer: as a fraction with 'tenths' (for example "18/10° DIN")

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

answer: with DIN 4512:1961-10

question: Why did the definition of film speeds change considerably? 

answer: to accommodate then-recent changes in the American ASA PH2.5-1960 standard

question: What happened to film speeds of black-and-white negative film? 

answer: would become doubled
Title: Film_speed
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.

question: What took the place of the German DIN 4512 system? 

answer: ISO 6:1974, ISO 2240:1982, and ISO 5800:1979

question: How is sensitivity shown in the ISO systems? 

answer: in linear and logarithmic form as "ISO 100/21°"

question: What standards did the DIN begin to use? 

answer: ISO standards

question: When were the ISO standards first adopted? 

answer: in the 1980s

question: When were the last ISO standards adopted?  

answer: July 2002
Title: Film_speed
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.

question: What system was used previous to the ASA system? 

answer: the system of Weston film speed ratings

question: Who devised the Weston film speed ratings?  

answer: Edward Faraday Weston (1878–1971) and his father Dr. Edward Weston (1850–1936)

question: What company did Dr. Edward Weston start?  

answer: the US-based Weston Electrical Instrument Corporation

question: When was the Weston model 617 created? 

answer: August 1932

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

answer: William Nelson Goodwin, Jr.
Title: Film_speed
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.

question: Which cameras were first of their type to adopt the ASA scale? 

answer: 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)

question: What were updated Weston values based on? 

answer: the ASA system

question: How were Weston values changed to ASA values? 

answer: by subtracting 1/3 exposure stop

question: Beginning with which year was the Weston to ASA conversion not necessary? 

answer: 1956

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

answer: 1955
Title: Film_speed
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.

question: Which company adopted the ASA scale in 1946? 

answer: General Electric

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

answer: 1946

question: How did older models convert to ASA scale? 

answer: replaceable hoods with ASA scales

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

answer: labeled "Exposure Index"

question: What were recommended film values lined up with after 1946? 

answer: they were now aligned to the ASA scale
Title: Film_speed
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).)

question: Who pioneered research that led to the new ANSI values? 

answer: Loyd Ancile Jones

question: What standards were the ANSI developed from? 

answer: Weston film speed ratings and General Electric film values

question: What types of film did the ANSI measure? 

answer: black-and-white negative films

question: When did the ANSI define its new measure? 

answer: 1943

question: What were ANSI values often called in the beginning? 

answer: American standard speed numbers or ASA exposure-index numbers
Title: Film_speed
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.

question: In what year were big changes made to the ANSI? 

answer: 1960

question: What did the 1960 changes to film speed measures lead to? 

answer: effectively doubling the nominal speed of many black-and-white negative films

question: Which other system were these changes applied to? 

answer: the DIN system

question: In what year was the BS system modified? 

answer: 1963

question: What safety factors were done away with beginning with the modifications to the standards? 

answer: safety factors against under-exposure
Title: Film_speed
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:

question: What is the plot from which film speed is derived called? 

answer: the D–log H curve or Hurter–Driffield curve

question: How many regions does the Hurter-Driffield curve have? 

answer: five

question: What is plotted in the Hurter-Driffield curve? 

answer: a plot of optical density vs. log of exposure for the film

question: What is denoted when the specified contrast condition is met? 

answer: The exposure Hm, in lux-s

question: What are the five regions of the Hurter-Driffield curve? 

answer: the base + fog, the toe, the linear region, the shoulder, and the overexposed region
Title: Film_speed
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.

question: What is the effective f-number proportional to? 

answer: the ratio between the lens focal length and aperture diameter

question: What is used to discover the right exposure parameters? 

answer: Film speed

question: What variables help the photographer produce the desired effect? 

answer: lighting, film speed, f-number (aperture size), and shutter speed (exposure time)

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? 

answer: twice as much

question: In the APEX system, the increment that doubles the exposure is called what? 

answer: "stop"
Title: Film_speed
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.

question: What determines the effect on the emulsion after exposure? 

answer: the amount of light energy that reaches the film

question: In what range of exposures does reciprocity usually work? 

answer: between 1/1000 second to 1/2 second

question: How is the exposure of film changed? 

answer: by varying the camera's shutter speed and aperture

question: How are ways of finding an emulsion's sensitivity possible? 

answer: because reciprocity holds

question: What happens outside the 1/1000 second to 1/second exposure range? 

answer: reciprocity failure
Title: Film_speed
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.

question: What are two examples of films that are marketed with speeds above their true ISO speed? 

answer: Ilford Delta 3200 and Kodak T-MAX P3200

question: What speed of film is the Ilford Delta 3200? 

answer: ISO 1000

question: Which two companies produced E6 films meant for "pushing"? 

answer: Kodak and Fuji

question: What is the base speed of Ektachrome P800/1600 and Fujichrome P1600? 

answer: ISO 400

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

answer: high-speed black-and-white films
Title: Film_speed
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.

question: What is another name for an exposure index rating? 

answer: ISO setting

question: How do some camera designs give some EI choices? 

answer: by adjusting the sensor's signal gain in the digital realm

question: Who provides the exposure index rating? 

answer: the manufacturer

question: What are digital photo cameras also called? 

answer: digital still cameras
Title: Film_speed
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.

question: What types of cameras have proven to be much more sensitive to light than film? 

answer: Digital cameras

question: What ISO equivalent speeds can digital cameras obtain? 

answer: 409,600

question: What is responsible for these vast increases in speed? 

answer: Faster processors, as well as advances in software noise reduction techniques

question: What is one thing that limited speeds of older digital hardware? 

answer: prohibitively time consuming to process

question: What does the higher speed do for the images produced? 

answer: a higher level of refinement
Title: Film_speed
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.

question: How many techniques are available because of ISO 12232:2006? 

answer: five

question: What techniques did CIPA DC-004 provide? 

answer: two new techniques allowing for measurement of JPEG output files

question: What factors affect the exposure index rating? 

answer: the sensor sensitivity, the sensor noise, and the appearance of the resulting image

question: What does the standard of ISO 12232:2006 specify? 

answer: the measurement of light sensitivity of the entire digital camera system and not of individual components

question: In what year did Kodak start using a different way of characterizing two sensors? 

answer: 2001