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128-476: Until the late 1960s, cameras did not have built-in exposure meters , and many photographers did not have external exposure meters. Consequently, it often was necessary to calculate exposure from lighting conditions. The relationship of recommended photographic exposure to a scene's average luminance is given by the camera exposure equation where Use of the symbol B {\displaystyle B} for luminance reflects photographic industry practice at

256-558: A "ladies camera" – a Rolleiflex that used 35 mm film . This was the first Rolleiflex to come on the market that used a crank handle to advance the film, a popular feature that emerged on the 6×6 model shortly thereafter. The Rolleiflex 4×4 – known as the Babyflex outside of Germany – used 127 format film and came in two versions with either a f/3.5 and a f/2.8 Tessar lens with a focal length of 60 mm. Unfortunately, sales were disappointing, so production never resumed after

384-508: A 'TAv' exposure mode to automatically set the ISO speed depending on the desired aperture and shutter settings, and 'Sv' (for sensitivity priority) to pre-set the ISO speed and let the camera choose the other parameters. Some meters, such as Pentax spot meters , directly indicate the exposure value for ISO 100 film speed. For a given film speed, exposure value is directly related to luminance, although

512-472: A built-in meter that measures a scene-wide light level and are able to make an approximate measure of appropriate exposure based on that. Photographers working with controlled lighting and cinematographers use handheld light meters to precisely measure the light falling on various parts of their subjects and use suitable lighting to produce the desired exposure levels. Exposure meters generally are sorted into reflected-light or incident-light types, depending on

640-416: A camera would make studio work more straightforward; at that time, the photographer had to stoop under a black cloth to adjust the camera, and then address the subject from this awkward position. Nevertheless, after the failure of the Babyflex , the company proceeded with caution by initially building some prototypes. One was delivered to Kahn, and the others were shipped abroad in pairs – one to be retained by

768-507: A chart of appropriate aperture and shutter speed combinations for a given film speed . Extinction meters tended to provide inconsistent results because they depended on subjective interpretation and the light sensitivity of the human eye , which can vary from person to person. Later meters removed the human element and relied on technologies incorporating selenium , CdS , and silicon photodetectors . Selenium and silicon light meters use sensors that are photovoltaic : they generate

896-529: A film format that Kodak , the market leader, did not support was foolhardy. Needless to say, the quality of the engineering in the Rollei ;16 matched its high price; it had a push-pull viewfinder with automatic parallax correction up to 40 cm, whereby extending the viewfinder also wound on the film and cocked the shutter. In addition, Mutar wide-angle (0.5×) and telephoto (1.7×) conversion lenses were available as accessories. An improved successor,

1024-442: A film whose spectral sensitivity is not a good match to that of the light meter, for example orthochromatic black-and-white or infrared film, the meter may require special filters and re-calibration to match the sensitivity of the film. There are other types of specialized photographic light meters. Flash meters are used in flash photography to verify correct exposure. Color meters are used where high fidelity in color reproduction

1152-456: A flat receptor with a reflected-light measurement of a uniformly illuminated flat surface of constant reflectance. Using values of 12.5 for K {\displaystyle K} and 250 for C {\displaystyle C} gives With a K {\displaystyle K} of 14, the reflectance would be 17.6%, close to that of a standard 18% neutral test card. In theory, an incident-light measurement should agree with

1280-445: A flat subject. For determining practical photographic exposure, a hemispherical receptor has proven more effective. Don Norwood , inventor of incident-light exposure meter with a hemispherical receptor, thought that a sphere was a reasonable representation of a photographic subject. According to his patent ( Norwood 1938 ), the objective was to provide an exposure meter which is substantially uniformly responsive to light incident upon

1408-805: A further 700 workers. It was completed in 1938, and by the end of that year the 300,000th camera had come off the production line. In retrospect, Reinhold Heidecke regarded the Rolleiflex Automat as his favourite camera. During World War II , the company was required by the Nazis to support the war economy . As a result, Rollei was unable to develop any new models from 1940, and production of its stereo camera finally came to an end. Rollei also suffered massive losses resulting from its inability to collect monies owed by debtors from "enemy states". Furthermore, bureaucratic formalities and controls hindered exports to neutral countries. This situation, combined with

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1536-520: A hemispherical receptor indicate "effective scene illuminance." It is commonly stated that reflected-light meters are calibrated to an 18% reflectance, but the calibration has nothing to do with reflectance, as should be evident from the exposure formulas. However, some notion of reflectance is implied by a comparison of incident- and reflected-light meter calibration. Combining the reflected-light and incident-light exposure equations and rearranging gives Reflectance R {\displaystyle R}

1664-498: A hemispherical receptor when metering with an off-axis light source. In practice, additional complications may arise. Many neutral test cards are far from perfectly diffuse reflectors, and specular reflections can cause increased reflected-light meter readings that, if followed, would result in underexposure. It is possible that the neutral test card instructions include a correction for specular reflections. Light meters or light detectors are also used in illumination . Their purpose

1792-399: A light meter consists of a radiometer (the electronics/readout), a photo-diode or sensor (generates an output when exposed to electromagnetic radiation/light) a filter (used to modify the incoming light so only the desired portion of incoming radiation reaches the sensor) and a cosine correcting input optic (assures the sensor can see the light coming in from all directions accurately). When

1920-459: A longer exposure time or a smaller f {\displaystyle f} -number. The sense of exposure compensation is opposite that of the EV scale itself. An increase in exposure corresponds to a decrease in EV, so an exposure compensation of +1 EV results in a smaller EV; conversely, an exposure compensation of −1 EV results in a greater EV. APEX has seen a partial resurrection in

2048-490: A new electronic shutter at photokina 2012 . DHW itself filed for insolvency on 15 August 2014 and was dissolved in April 2015, thereby temporarily ending any further production of cameras, lenses and accessories. A new, smaller company called DW Photo was formed with reduced staffing, and more or less the same people leading the business; the manufacturing and sale of projectors and twin-lens reflex cameras, as well as that of

2176-420: A noisy factory operating within a residential area and pressured the company to move its factory elsewhere. Accordingly, on 10 January 1923 the company purchased a 60,000 m (15 acres) plot of land on Salzdahlumer Straße, which at that time lay just beyond the city limits. Hyperinflation had devalued the currency so much that the land purchase cost practically nothing. Once the new factory had been built, much

2304-622: A number of photographs, for which the exposure was known, obtained under various conditions of subject manner and over a range of luminances. In practice, the variation of the calibration constants among manufacturers is considerably less than this statement might imply, and values have changed little since the early 1970s. ISO 2720:1974 recommends a range for K {\displaystyle K} of 10.6 to 13.4 with luminance in cd/m . Two values for K {\displaystyle K} are in common use: 12.5 ( Canon , Nikon , and Sekonic ) and 14 ( Minolta , Kenko , and Pentax );

2432-461: A one degree circular angle of view . An experienced photographer can take multiple readings over the shadows, midrange, and highlights of the scene to determine optimal exposure, using systems like the Zone System . Many modern cameras include sophisticated multi-segment metering systems that measure the luminance of different parts of the scene to determine the optimal exposure. When using

2560-421: A picture, two separate steps were required to advance the film and cock the shutter . The Rolleiflex Automat combined the two, whereby advancing the film automatically cocked the shutter. Not only did this innovation speed up the whole process, it also eliminated accidental double exposures resulting from inadvertently forgetting to wind on the film. It also had a film-feeler mechanism that automatically started

2688-400: A power source such as batteries to operate. CdS light meters use a photoresistor sensor whose electrical resistance changes proportionately to light exposure. These also require a battery to operate. Most modern light meters use silicon or CdS sensors. They indicate the exposure either with a needle galvanometer or on an LCD screen. Many modern consumer still and video cameras include

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2816-420: A reading would incorrectly compensate for the difference in reflectance and lead to underexposure. Badly underexposed sunset photos are common exactly because of this effect: the brightness of the setting sun fools the camera's light meter and, unless the in-camera logic or the photographer take care to compensate, the picture will be grossly underexposed and dull. This pitfall (but not in the setting-sun case)

2944-452: A reflected-light measurement and an incident-light measurement is valid for any position of the light source. However, the response of a hemispherical receptor to an off-axis light source is approximately that of a cardioid rather than a cosine , so the 12% "reflectance" determined for an incident-light meter with a hemispherical receptor is valid only when the light source is on the receptor axis. Calibration of cameras with internal meters

3072-601: A reflected-light measurement of a test card of suitable reflectance that is perpendicular to the direction to the meter. However, a test card seldom is a uniform diffuser, so incident- and reflected-light measurements might differ slightly. In a typical scene, many elements are not flat and are at various orientations to the camera, so that for practical photography, a hemispherical receptor usually has proven more effective for determining exposure. Using values of 12.5 for K {\displaystyle K} and 330 for C {\displaystyle C} gives With

3200-478: A result, Rollei developed the Rolleimarin , an ingenious underwater camera housing rated for depths up to 100 m. It was made from two cast metal parts. The top part contained a glass prism that was attached to the camera's focusing screen . There were also knobs on top of the housing for adjusting the exposure and aperture settings. On the bottom, left-hand side of the housing was the focusing knob, and on

3328-426: A scene. Light meters also are used in the general field of architectural lighting design to verify proper installation and performance of a building lighting system, and in assessing the light levels for growing plants. If a light meter is giving its indications in luxes , it is called a " luxmeter ". The earliest exposure meters were called actinometers (not to be confused with the scientific instrument with

3456-577: A single, fixed normal lens, although the Rollei Magnar tele-converter lens with 4x magnification was available as an accessory. This could be attached to the front of the primary lens while a mask (which did not magnify the image) was placed over the focusing screen. In addition, Zeiss offered two double lens converters which attached to the viewfinder filter bayonet and the primary lens bayonet. The 5-element Mutar tele-converter magnified 1.5×, weighed 327 g and could render an image accurately in

3584-465: A slightly revised definition of reflectance, this result can be taken as indicating that the average scene reflectance is approximately 12%. A typical scene includes shaded areas as well as areas that receive direct illumination, and a wide-angle averaging reflected-light meter responds to these differences in illumination as well as differing reflectances of various scene elements. Average scene reflectance then would be where "effective scene illuminance"

3712-502: A variety of models. The company expanded its production facilities and product range at the end of the 1960s beyond what a small company like Rollei could manage. Rollei's decision to start manufacturing in Singapore in 1970 was regarded as a pioneering achievement by the photographic industry. Unfortunately, it also damaged the companies reputation as a German precision manufacturer. In 1982, after many failed attempts at restructuring ,

3840-494: A voltage proportional to light exposure. Selenium sensors generate enough voltage for direct connection to a meter; they need no battery to operate and this made them very convenient in completely mechanical cameras. Selenium sensors however cannot measure low light accurately (ordinary lightbulbs can take them close to their limits) and are altogether unable to measure very low light, such as candlelight, moonlight, starlight etc. Silicon sensors need an amplification circuit and require

3968-523: A wide margin. Even though it was quite an expensive product, orders for 800 cameras were received in the first month alone. A Rolleiflex fitted with a f/4.5 lens cost 198  ℛ︁ℳ︁ , with a f/3.8 lens it cost 225 ℛ︁ℳ︁. This success made it possible to obtain credit to buy a new factory and thrive in the midst of the Great Depression . In the old factory, a further 23,720 cameras were produced up until 1932. In 1930,

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4096-424: A wide-angle averaging reflected-light measurement may not indicate the correct exposure. To simulate an average scene, a substitute measurement sometimes is made of a neutral test card, or gray card . At best, a flat card is an approximation to a three-dimensional scene, and measurement of a test card may lead to underexposure unless adjustment is made. The instructions for a Kodak neutral test card recommend that

4224-663: A year, Franke and Heidecke had taken over the entire building. By 1922, business was so good that they were able to take out a loan to purchase the property outright. To get the company going, Franke and Heidecke decided to manufacture a stereo camera in the short term. Cameras of this type were popular, and Reinhold Heidecke was very familiar with them. As they were also in Voigtländer's product range, however, Franke and Heidecke did not want to look as if they were simply copying theirs. They purchased several Voigtländer units, and from what they learned by dismantling these, constructed

4352-433: Is avoided by incident-light meters which measure the amount of light falling on the subject using a diffuser with a flat or (more commonly) hemispherical field of view placed on top of the light sensor. Because the incident-light reading is independent of the subject's reflectance, it is less likely to lead to incorrect exposures for subjects with unusual average reflectance. Taking an incident-light reading requires placing

4480-424: Is covered by ISO 2721:1982 ; nonetheless, many manufacturers specify (though seldom state) exposure calibration in terms of K {\displaystyle K} , and many calibration instruments (e.g., Kyoritsu-Arrowin multi-function camera testers ) use the specified K {\displaystyle K} to set the test parameters. If a scene differs considerably from a statistically average scene,

4608-405: Is defined as A uniform perfect diffuser (one following Lambert's cosine law ) of luminance L {\displaystyle L} emits a flux density of π {\displaystyle \pi } L {\displaystyle L} ; reflectance then is Illuminance is measured with a flat receptor. It is straightforward to compare an incident-light measurement using

4736-429: Is discussed briefly by Adams (1981 , 39). Modern cameras no longer display exposure values as such, but continue to offer exposure modes, which support users in employing the concept of counter-adjusting shutter speed and aperture at a fixed point of exposure. This can be found in features such as Manual Shift on some Minolta , Konica Minolta and Sony Alpha or Hyper Manual on some Pentax (D)SLRs since 1991, where

4864-599: Is in agreement with the APEX value for B {\displaystyle B} , but would imply K = 1 / N {\displaystyle K=1/N} , or 3.125 with B {\displaystyle B} in footlamberts. With B {\displaystyle B} in cd/m, this becomes 10.7, which is slightly less than the value of 12.5 recommended by ISO 2720:1974 and currently used by many manufacturers. The difference possibly arises from rounding B {\displaystyle B} in

4992-422: Is named Empfindlichkeitsleitwert , and the brightness value B v {\displaystyle B_{v}} is known as Objekthelligkeit .) APEX made exposure computation a relatively simple matter; the foreword of ASA PH2.5-1960 recommended that exposure meters, exposure calculators, and exposure tables be modified to incorporate the logarithmic values that APEX required. In many instances, this

5120-571: Is reasonable because several of the quantity symbols ( E {\displaystyle E} , B {\displaystyle B} , and I {\displaystyle I} for exposure, luminance, and illuminance) used at the time APEX was proposed are in conflict with current preferred SI practice. A few artifacts of APEX remain. Canon , Pentax and Leica cameras use 'Av' and 'Tv' to indicate relative aperture and shutter speed as well as to symbolize aperture priority and shutter priority modes. Some Pentax DSLRs even provide

5248-437: Is required. Densitometers are used in photographic reproduction. In most cases, an incident-light meter will cause a medium tone to be recorded as a medium tone, and a reflected-light meter will cause whatever is metered to be recorded as a medium tone. What constitutes a "medium tone" depends on meter calibration and several other factors, including film processing or digital image conversion. Meter calibration establishes

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5376-401: Is that measured by a meter with a hemispherical receptor. ISO 2720:1974 calls for reflected-light calibration to be measured by aiming the receptor at a transilluminated diffuse surface, and for incident-light calibration to be measured by aiming the receptor at a point source in a darkened room. For a perfectly diffusing test card and perfectly diffusing flat receptor, the comparison between

5504-401: Is to measure the illumination level in the interior and to switch off or reduce the output level of luminaires . This can greatly reduce the energy burden of the building by significantly increasing the efficiency of its lighting system. It is therefore recommended to use light meters in lighting systems, especially in rooms where one cannot expect users to pay attention to manually switching off

5632-533: The Mamiya C-Series from Japan appeared in 1956. Mamiya initially offered three sets of interchangeable double lenses for it: normal, telephoto and wide-angle. Later on, additional double lenses with focal lengths of 55 mm and 250 mm were introduced; one even had a dimmable viewfinder lens, which enabled depth of field adjustment through the viewfinder. By comparison, the Rolleiflex only had

5760-584: The Exif standard, which calls for storing exposure data using APEX values. There are some minor differences from the original APEX in both terminology and values. The implied value (1/3.125) for the speed scaling constant N {\displaystyle N} given in the Exif 2.2 specification ("Exif 2.2"; JEITA 2002 ) differs slightly from the APEX value of 2 − 7 / 4 {\displaystyle 2^{-7/4}} (0.2973); with

5888-579: The Magic II , cost 498 DM and also featured manual exposure control. Some accessories manufactured for Rollei TLRs: By the end of 1950s, the market for twin-lens medium format cameras had gradually become saturated. More and more amateur photographers and photojournalists were using 35 mm format cameras, while studio photographers preferred single-lens medium format cameras. Although they were more expensive, single-lens cameras offered film holders , which could quickly be swapped (an assistant loaded

6016-511: The Rollei 16S , was released in 1965. To help return the company to profitability, Rollei's management sought advice from a number of experts. One of them, Heinrich Peesel , a physicist from Hamburg, produced a concise, 5-page report that so impressed Rollei management that they offered him the chairmanship of the board, thereby accepting that far-reaching changes were necessary. Peesel, then 38 years old, thus succeeded Horst Franke as chairman of

6144-590: The Soviet occupation zone . Franke & Heidecke started over with 72 workers, and by Christmas 1945 the workforce had grown to 172 employees. Everything the company made in 1945 was delivered to the British Ministry of Defence . The difficult supply situation forced Rollei into using lenses from the West German manufacturer Schneider as well. However, this was not a problem as Schneider's quality control

6272-760: The Stereo Heidoscop . It included two Carl Zeiss Tessar lenses (f/4.5, 55 mm) and, mounted between them, a Carl Zeiss Super Triplet (f/3.2) viewfinder. At that time, Tessar lenses were widely regarded as the best available; they were often used in the United States, even though locally produced alternatives were available. Zeiss had an excellent reputation world-wide, which Franke & Heidecke leveraged for their own products. More importantly, they differentiated themselves from cheaper alternatives. The camera projected an image onto glass plates of dimensions 45 mm × 107 mm. The name Heidoscop

6400-578: The "Rollei" and "Rolleiflex" brands. Finally, Rollei Metric GmbH took over the photogrammetry business. In early 2009, Franke & Heidecke GmbH, Feinmechanik und Optik declared itself insolvent. Since 2009 Rolleiflex medium format cameras, Rollei 35 and Rolleivision slide projectors were being produced by the DHW Fototechnik GmbH —a company founded by Rolf Daus, Hans Hartje and Frank Will, former Franke & Heidecke employees. DHW Fototechnik presented two new Rolleiflex cameras and

6528-678: The "Rollei" label in Europe. Rollei was a German company that established a worldwide reputation with the Rolleiflex , a twin-lens reflex camera . Rollei was founded in 1920 as the Werkstatt für Feinmechanik und Optik, Franke & Heidecke in order to make a twin-lens reflex camera . The company changed its name and legal form many times: to Rollei-Werke Franke & Heidecke in 1962, to Rollei-Werke Franke & Heidecke GmbH & Co. KG in 1979, to Rollei Fototechnic GmbH & Co. KG in 1981, and finally to Rollei GmbH in 2004. In 2006,

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6656-468: The 9 cm × 9 cm film format. Kahn explained as a pretext, that his customers liked to keep the negatives because they had doubts about the durability of prints. Moreover, roll film was much easier to archive than glass plates. In fact, Kahn had concealed the real rationale behind his request because Franke & Heidecke supported the Nazi Party in order to get the workers they needed. Fearing

6784-532: The Appendix). The incorporation of exposure meters in many cameras in the late 1960s eliminated the need to compute exposure, so APEX saw little actual use. With the passage of time, formatting of APEX quantities has varied considerably; although the v {\displaystyle v} originally was subscript, it sometimes was given simply as lower case, and sometimes as uppercase. Treating these quantities as acronyms rather than quantity symbols probably

6912-556: The Exif value, an ISO arithmetic film speed of 100 corresponds exactly to a speed value S v {\displaystyle S_{\mathrm {v} }} of 5. The relationship between B v {\displaystyle B_{\mathrm {v} }} and luminance depends on both the speed scaling constant N {\displaystyle N} and the reflected-light meter calibration constant K {\displaystyle K} : Because Exif 2.2 records ISO arithmetic speed rather than film sensitivity,

7040-407: The amount of light. In photography , an exposure meter is a light meter coupled to either a digital or analog calculator which displays the correct shutter speed and f-number for optimum exposure , given a certain lighting situation and film speed . Similarly, exposure meters are also used in the fields of cinematography and scenic design , in order to determine the optimum light level for

7168-411: The aperture value A v {\displaystyle A_{v}} is referred to as Blendenleitwert L W k {\displaystyle LWk} , and the time value T v {\displaystyle T_{v}} as Zeitleitwert L W t {\displaystyle LWt} . The film speed value S v {\displaystyle S_{v}}

7296-481: The bulk of the companies resources, some regular product development was still possible, and work on tempered glass lenses as well as flash synchronization continued, albeit on a small scale. The cameras were used inter alia in military reconnaissance . As Braunschweig was one of the centres of the German armaments industry , it was subjected to frequent, sometimes heavy aerial bombardment , which seriously damaged

7424-404: The calibration constant K {\displaystyle K} is missing, but with luminance in cd/ft, the value was unity ( ASA Z38.2.6-1948 specified a range of 1–1.35; ASA PH2.12-1961 specified 1.06 ± 0.16. The current recommendation in ISO 2720:1974 would be 0.98–1.24 with luminance in cd/ft). Exposure meter A light meter (or illuminometer ) is a device used to measure

7552-410: The camera, both made of aluminium, had to be handled with care, which remained the case until the camera went into production. One more prototype was produced in 1928, and then the big moment finally arrived: on 10 August, the first camera went into series production. Altogether, 14 units were made that year. Then, at 11am on Monday, 11 December, selected journalists were invited to a press conference in

7680-497: The challenge from Mamiya, Rollei created a camera comparable to the C Series and gave it to photojournalists to test. Although they were enthusiastic, Rollei did not believe – much to the astonishment of industry experts – that it could manufacture removable lenses with the required precision. Instead, as a compromise, the company introduced in 1959 the Tele-Rolleiflex with a Zeiss Sonnar f/4, 135 mm lens. This camera

7808-474: The city. On 1 and 15 January 1944, and again on 13 August, Rollei too suffered air raid damage to its factories. By the time the war ended on 12 April 1945, almost 65% of its plant and machinery had been destroyed. After the war, Braunschweig ended up in the British occupation zone . The allied occupying forces wanted Rollei to survive as a company, even helping it procure lenses from Zeiss, which had ended up in

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7936-442: The collapse in overseas trade, forced Paul Franke to reduce the workforce to 600 people. Alongside its renowned cameras, Rollei – like its neighbour Voigtländer – was now engaged in the manufacture of equipment deemed important to the German war effort: precision optics for binoculars , periscopes , telescopic sights (for sniper rifles , for example), and theodolites for directing artillery . Although these products consumed

8064-715: The company finally achieved success by focusing on medium format cameras along with a few other products. Surveying systems were added to the product range in 1986, and modern digital and compact cameras were included from 1991. Over the years, many great photographers have used Rollei cameras: David Bailey and Diane Arbus (Rolleiflex 3.5F TLR with 75 mm f/3.5 Planar), Brett Weston (Rolleiflex SL66 and SL66E SLR), and Helmut Newton (Rolleiflex 2.8GX), amongst others. Rollei cameras typically used Carl Zeiss or Schneider Kreuznach lenses, as well as lenses manufactured by Rollei based on designs by Zeiss, and occasionally lenses made by Japanese manufacturers. While Reinhold Heidecke

8192-467: The company moved into the new factory on Salzdahlumer Straße. It comprised two floors with a total area of 2,000 square metres ( 1 ⁄ 2 acre), sufficient space to manufacture 20,000 cameras annually. Although the site was well served by public transport, it lay some distance from the city centre, so the company built a canteen and shop for its workforce, which now numbered 309 employees. Wilhelmine Heidecke, Reinhold Heidecke's wife, suggested building

8320-439: The consequences of leasing to a Jew, the owner of his studio had already shut off his water supply. This meant that Kahn had to develop his negatives at home, whereby roll film was easier to transport than plates. A roll film camera would also facilitate house calls. Having built a small Rolleiflex , the obvious next step was to make a larger version. Indeed, the slogan "you see what you get" had already been envisaged for it. Such

8448-571: The counter, so no red window was needed. The Rolleiflex Automat won the Grand Prix award at the Paris World's Fair in 1937, which generated a lot of interest. The company founders we so taken with their new creation that they immediately commissioned the construction of a second factory. The new factory, comprising three floors with a combined production area of 3,000 square metres ( 3 ⁄ 4 acre), provided sufficient space to house

8576-463: The development costs any more. One of his projects was the Magic , which required several expensive machine tools to be built – expenditure that could not be justified relative to the small number that were produced. In contrast, Agfa preferred the opposite approach, of always developing as many models as possible from an existing camera housing. The Magic , although intended for amateur photographers,

8704-533: The difference between the two values is approximately 1 ⁄ 6 EV . The earliest calibration standards were developed for use with wide-angle averaging reflected-light meters ( Jones and Condit 1941 ). Although wide-angle average metering has largely given way to other metering sensitivity patterns (e.g., spot, center-weighted, and multi-segment), the values for K {\displaystyle K} determined for wide-angle averaging meters have remained. The incident-light calibration constant depends on

8832-544: The end, Horst Franke relinquished his position as general manager. In 1960, Rollei introduced its first slide projector , the P11 . It included two slide trays: the left-hand tray was for 35 mm (5 cm×5 cm) slides, the right-hand tray was for medium format (7 cm×7 cm) slides. The Rollei Universal Projector sold for 398.60 DM, plus 97.50 DM for a standard lens. The P11 remained in production until 1978; many more projectors were subsequently added to

8960-649: The example table; it also is possible that the example data simply were copied from an old ASA or ANSI standard. To use the Exposure Formula, take the film speed number (on the ASA scale) and determine its approximate square root. This number is remembered as the key stop for that film. ... At the key stop, the correct shutter speed is the reciprocal of the luminance expressed in c/ft. Using these values for A {\displaystyle A} and T {\displaystyle T} gives Ostensibly,

9088-475: The exposure equation and separating numerators and denominators reduces exposure calculation to a matter of addition: where ASA standards covered incident-light meters as well as reflected-light meters; the incident-light exposure equation is where The use of I {\displaystyle I} for illuminance reflects photographic industry practice at the time of the 1961 ASA standard for exposure meters, ASA PH2.12-1961 ; current SI practice prefers

9216-550: The exposure equation, E v {\displaystyle E_{v}} denoted combinations of camera settings; when applied to the right-hand side, E v {\displaystyle E_{v}} denoted combinations of luminance and film speed. For a given film speed, the recommended exposure value was determined solely by the luminance. Once the exposure value was determined, it could be directly set on cameras with an E v {\displaystyle E_{v}} scale. Adjustment of exposure

9344-436: The exposure equation, it generally was assumed that doing so would prove too daunting for the casual photographer. The 1942 ASA exposure guide, ASA Z38.2.2-1942 , featured a dial calculator, and revisions in 1949 and 1955 used a similar approach. An alternative simplification also was possible: ASA PH2.5-1960 proposed extending the concept of exposure value to all exposure parameters. Taking base-2 logarithms of both sides of

9472-418: The exposure value, adjusting either the shutter speed or aperture made a corresponding adjustment in the other to maintain a constant exposure. On some models, the coupling of shutter speed and aperture setting was optional, so that photographers could choose their preferred method of working depending on the situation. Use of the E v {\displaystyle E_{v}} scale on such cameras

9600-443: The festively decorated production area. Paul Franke put together press packs for the occasion, which led one magazine to publish a test report without ever actually handling the camera. Although Franke had forgotten to prepare sample photographs to distribute to the press, he neatly avoided this oversight by distributing empty, labelled cartons around the building, just for show. Demand for the new camera exceeded production capacity by

9728-412: The film simply required inserting the leader into the appropriate slot in the camera. Since there was no take-up spool, the film coiled up loosely on itself. Without a doubt, limited film choice and availability adversely affected camera sales, consequently only 25,000 units were produced. As Rollei also spent a lot on advertising, this camera did little to alleviate its dire financial situation. Reliance on

9856-460: The film), as well as interchangeable lenses. Hasselblad was the market leader in this segment. The Swedish company introduced their first camera, the Hasselblad 1600F , in 1948. However, this model was regarded as being technically inferior because its shutter was unreliable. To solve this problem, the 1000F was released in 1952 with a reduced shutter speed range, but the focal-plane shutter

9984-501: The filtration matches the human eyes' response. Rollei Rollei ( German pronunciation: [ˈʁɔlaɪ] ) was a German manufacturer of optical instruments founded in 1920 by Paul Franke  [ de ] and Reinhold Heidecke  [ de ] in Braunschweig , Lower Saxony, and maker of the Rolleiflex and Rolleicord series of cameras. Later products included specialty and nostalgic type films for

10112-414: The flexibility required to adapt to changing circumstances; for example, he failed to reduce the workforce in difficult times, whereas Paul Franke had done so immediately at the onset of the war. To begin with, Rollei had no real competition, which yielded ever increasing sales of its cameras. In the 1950s, almost every press photographer owned a Rolleiflex , and quite a few amateurs did as well. The camera

10240-421: The greatest density that still allowed incident light to pass through. In another example, sold as Heyde's Aktino-Photometer starting from the early 1900s, the photographer views the scene through an eyepiece and turns the meter to vary the effective density until the scene can no longer be seen. The letter or number corresponding to the filter strength causing the "extinction" of the scene was used as an index into

10368-471: The headquarters of Rollei GmbH were moved to Berlin while production was transferred to Rollei Produktion GmbH , currently Franke & Heidecke GmbH , in Braunschweig. The company underwent more radical restructuring in 2007/2008. The frequent name-changes are an indication of a turbulent history: After the popularity of the twin lens reflex cameras declined, the Rolleiflex was supplemented with

10496-409: The imaging lens and surrounding the opening for the optical path was a large cogwheel which drove four smaller cogs located top left and right, and bottom left and right. Each of the four small cogs drove rack and pinions (toothed rails) attached to the lens assembly. This system functioned perfectly, and, thanks to high-quality components, also for many years of service. Only the viewfinder and back of

10624-535: The importer as a demonstration unit, the other to be delivered to a reputable studio. The project was eventually abandoned after Salomon Kahn was arrested and nobody else showed any interest in the studio camera. Of the 14 prototypes that were built, one still exists: it currently belongs to the Municipal Museum of Braunschweig. In 1933, the Rolleicord , a cheaper version of the Rolleiflex , came onto

10752-415: The incident-light exposure equation: where Determination of calibration constants has been largely subjective; ISO 2720:1974 states that The constants K {\displaystyle K} and C {\displaystyle C} shall be chosen by statistical analysis of the results of a large number of tests carried out to determine the acceptability to a large number of observers, of

10880-602: The indicated exposure be increased by 1 ⁄ 2 step for a frontlighted scene in sunlight. The instructions also recommend that the test card be held vertically and faced in a direction midway between the Sun and the camera; similar directions are also given in the Kodak Professional Photoguide . The combination of exposure increase and the card orientation gives recommended exposures that are reasonably close to those given by an incident-light meter with

11008-441: The insistence of his wife, he presented his concept to Paul Franke  [ de ] , a salesman and former colleague at Voigtländer. Franke was so enthusiastic he put up 75,000 M of his own money and went looking for more capital. After he secured additional funding of 200,000 M, they resolved to go into business together. In November 1919, they filed an application to register the company "Franke & Heidecke", which

11136-411: The lens because of an earlier, bad experience: around 1916, he conducted an experiment with a Kodak camera; he left it in a cellar, and when he later retrieved it, he found that rats had eaten the bellows. This convinced him that a camera designed for photojournalism and operation in the tropics had to work perfectly, which excluded components that might rot. He ruled out a cloth shutter curtain for

11264-497: The lights. Examples include hallways, stairs, and big halls. There are, however, significant obstacles to overcome in order to achieve a successful implementation of light meters in lighting systems, of which user acceptance is by far the most formidable. Unexpected or too frequent switching and too bright or too dark rooms are very annoying and disturbing for users of the rooms. Therefore, different switching algorithms have been developed: In Scientific Research & Development uses,

11392-507: The market. It had simpler Zeiss Triotar Lens, a steel back-plate, and a knob instead of a handle for winding on the film. The Rolleicord 1 cost 105  ℛ︁ℳ︁ ; altogether 2,699,505 Rolleicords were manufactured until production ceased in 1976. The later models (III - VB) uses Schneider Xenar lenses that have better optics. The release of the Rolleiflex Automat in the middle of June 1937 marked another significant milestone for Franke & Heidecke. Prior to this, after taking

11520-423: The meter at the subject's position and pointing it in the general direction of the camera, something not always achievable in practice, e.g., in landscape photography where the subject distance approaches infinity. Another way to avoid under- or over-exposure for subjects with unusual reflectance is to use a spot meter : a specialized reflected-light meter that measures light in a very tight cone , typically with

11648-410: The method used to measure the scene. Reflected-light meters measure the light reflected by the scene to be photographed. All in-camera meters are reflected-light meters. Reflected-light meters are calibrated to show the appropriate exposure for "average" scenes. An unusual scene with a preponderance of light colors or specular highlights would have a higher reflectance; a reflected-light meter taking

11776-399: The number and type of light sources; when each receptor is pointed at a small light source, a hemispherical receptor with C {\displaystyle C} = 330 will indicate an exposure approximately 0.40 step greater than that indicated by a flat receptor with C {\displaystyle C} = 250. With a slightly revised definition of illuminance, measurements with

11904-473: The period of hyperinflation in Germany, Paul Franke lived up to his reputation as a savvy financier: he invested the income from exports (in foreign currency) so astutely that the company came through this difficult period unscathed – a rather unlikely outcome if Heidecke, alone, had made these decisions. During this period the company acquired new premises. The City Council in Braunschweig did not really want

12032-481: The photo hobbyist market. Originally named Werkstatt für Feinmechanik und Optik, Franke & Heidecke , the company renamed into Rollei-Werke Franke & Heidecke GmbH in 1972, Rollei-Werke Franke & Heidecke GmbH & Co. KG , in 1979, and Rollei Fototechnic GmbH & Co. KG in 1981. After being purchased in 1995 by Samsung Techwin , part of the South Korean Samsung Group , it

12160-546: The photographer can change one of the parameters, and the camera will adjust the other accordingly for as long as the Auto-Exposure Lock (AEL) function is activated. In a wider sense, functions like Program Shift  [ de ] , Pa / Ps Creative Program Control (by Minolta, Konica Minolta and Sony) or Hyper Program (by Pentax) belong to this group of features as well. Although some photographers ( Adams 1981 , 66) routinely determined camera settings using

12288-567: The photographic subject from practically all directions which would result in the reflection of light to the camera or other photographic register. and the meter provided for "measurement of the effective illumination obtaining at the position of the subject." With a hemispherical receptor, ISO 2720:1974 recommends a range for C {\displaystyle C} of 320 to 540 with illuminance in lux; in practice, values typically are between 320 (Minolta) and 340 (Sekonic). The relative responses of flat and hemispherical receptors depend upon

12416-435: The range, providing a major boost to Rollei's turnover. In 1963, Rollei introduced the Rollei 16 , its first all-new camera design since the war. It was a 16 mm camera in the format 12 mm × 17 mm with a Tessar f/2.8, 25 mm lens and cost 425 DM. In retrospect, it seems unlikely that such an unusual format might return Rollei to profitability. However, the German camera industry believed that this

12544-529: The relationship between subject lighting and recommended camera settings. The calibration of photographic light meters is covered by ISO 2720:1974 . For reflected-light meters, camera settings are related to ISO speed and subject luminance by the reflected-light exposure equation: N 2 t = L S K {\displaystyle {\frac {N^{2}}{t}}={\frac {LS}{K}}} where For incident-light meters, camera settings are related to ISO speed and subject illuminance by

12672-515: The relationship depends on the reflected-light meter calibration constant K {\displaystyle K} . Most photographic equipment manufacturers specify metering sensitivities in EV at ISO 100 speed (the uppercase 'V' is almost universal). It is common to express exposure increments in EV, as when adjusting exposure relative to what a light meter indicates ( Ray 2000 , 316). For example, an exposure compensation of +1 EV (or +1 step) means to increase exposure, by using either

12800-406: The right-hand side, the winding handle and a frame counter. There was also a filter turret. A special flash bulb could be attached for flash photography, in which case a battery pack had to be installed inside the housing. Of course, a viewfinder frame could also be screwed onto the housing. Although there were many imitators, none could match the quality of the original Rolleiflex – that is, until

12928-496: The same name ), first developed in the late 1800s after commercial photographic plates became available with consistent sensitivity. These photographic actinometers used light-sensitive paper; the photographer would measure the time required for the paper to darken to a control value, providing an input to a mechanical calculation of shutter speed and aperture for a given plate number. They were popular between approximately 1890 and 1920. The next exposure meters, developed at about

13056-462: The same reason, choosing instead a Compur mechanical shutter . Focusing in the "Rolleiflex" was achieved by moving the carriage that held both the viewfinder and the imaging lens, i.e. the camera had so-called "metallic bellows"; that is, the plate enclosed the sides of the case. It was crucial that the plate remained parallel as it moved during focusing; to achieve this, Heidecke developed an ingenious design which proved to be highly successful. Behind

13184-400: The same time but not displacing actinometers in popularity until the 1920s and 1930s, are known as extinction meters , evaluating the correct exposure settings by variable attenuation. One type of extinction meter contained a numbered or lettered row of neutral density filters of increasing density. The photographer would position the meter in front of their subject and note the filter with

13312-686: The series 6000, was stopped, to concentrate on the Hy6 and accessories. A new battery and charger for owners of the 6000 series were however released to the market in 2019, as the original NiCd batteries could age prematurely. As of 2015 the brands "Rollei" and "Rolleiflex" continue to be owned by the RCP Technik Verwaltungs GmbH . On 1 January 2015, the RCP-Technik GmbH & Co. KG refirmed as Rollei GmbH & Co. KG to market digital consumer cameras and accessories under

13440-495: The symbol E {\displaystyle E} . ASA PH2.12-1961 included incident-light metering in the APEX concept: where (German sources typically use L W {\displaystyle LW} (for Lichtwert or Belichtungswert — but not to be confused with the English term light value ) instead of the exposure value's symbol E v {\displaystyle E_{v}} . Consequently,

13568-401: The time of ASA PH2.5-1960 ; current SI practice prefers the symbol L {\displaystyle L} . German sources typically used k {\displaystyle k} for the relative aperture. Many authors now use N {\displaystyle N} and t {\displaystyle t} for relative aperture and exposure time. Recommendations for

13696-459: The time production ceased in 1968, over 67,000 units had been made. By this time few amateur photographers made contact prints any more, preferring instead to take 35 mm transparencies (slides), which could be viewed on a slide projector . In 1932, Salomon Kahn, the owner of the renowned Fotostudios Kardas in Berlin, approached Rollei, asking if they could build him a large Rolleiflex for

13824-461: The type of light receptor. Two receptor types are common: flat ( cosine -responding) and hemispherical ( cardioid -responding). With a flat receptor, ISO 2720:1974 recommends a range for C {\displaystyle C} of 240 to 400 with illuminance in lux ; a value of 250 is commonly used. A flat receptor typically is used for measurement of lighting ratios, for measurement of illuminance, and occasionally, for determining exposure for

13952-563: The value of N {\displaystyle N} affects the recorded value of B v {\displaystyle B_{\mathrm {v} }} but not the recorded film speed. Exif 2.2 does not recommend a range of values for K {\displaystyle K} , presumably leaving the choice to the equipment manufacturer. The example data in Annex C of Exif 2.2 give 1 footlambert for B v {\displaystyle B_{\mathrm {v} }} = 0. This

14080-461: The value of the calibration constant K {\displaystyle K} in applicable ANSI and ISO standards have varied slightly over the years; this topic is discussed in greater detail under Exposure meter calibration in the Light meter article. In an attempt to simplify choosing among combinations of equivalent camera settings, the concept of exposure values (German: Lichtwert )

14208-454: The viewfinder up to a distance of 4m from the object. The 4-element Mutar wide-angle converter magnified 0.7×, weighed 437 g and could render an object accurately from a distance of 1 meter. In all cases, for the best image quality, closing down the aperture two stops was recommended. This explains why conversion lenses of this type were only regarded as a makeshift solution in comparison to fully interchangeable lenses. In response to

14336-410: The war. The company management believed that many Rollei photographers only made contact prints from their negatives because they had no access to enlargers . However, this was not practical in the case of the Babyflex as the negatives were simply too small. As a result, it was not until 1957 that a new version came onto the market priced at DM 355, firstly in grey, and later (from 1963) in black. By

14464-417: The word light meter or photometer is used in place of radiometer or optometer, or it is often assumed the system was configured to see only visible light. Visible light sensors are often called illuminance or photometric sensors because they have been filtered to be sensitive only to 400-700 nanometers (nm) mimicking the human eyes' sensitivity to light. How accurately the meter measures often depends on how well

14592-411: Was chosen in part to remind the management at Voigtländer that they had restricted Heidecke in his work there. The Heidoscop was a great success, exceeding all expectations. In 1923, the company introduced a Heidoscop for 117 format (B1) roll-film. It was from this product, the "'Roll-film Heidoscop"', that the name Rollei was derived, which later became the name of company. Between 1914 and 1923,

14720-459: Was done: the 1973 and 1986 ANSI exposure guides, ANSI PH2.7-1973 and ANSI PH2.7-1986 , eliminated exposure calculator dials in favor of tabulated APEX values. However, the logarithmic markings for aperture and shutter speed required to set the computed exposure were never incorporated in consumer cameras. Accordingly, no reference to APEX was made in ANSI PH3.49-1971 (though it was included in

14848-482: Was entered into the German Trade Register on 1 February 1920. In need of factory space, they rented several rooms in a house at Viewegstraße 32, which became the companies first headquarters. The house survived World War II intact and stands to this day. Other rooms in the house were used by a dancing school, who had to abandon their dancing lessons because of noise from the factory. Within

14976-449: Was equal to that of Zeiss. Paul Franke's untimely death in the spring of 1950 had serious consequences for the company though. Not only did his passing mark the end of an era for Rollei, the loss of his business acumen also led the company to the edge of ruin on more than one occasion. After Paul Franke's death, his son Horst Franke succeeded him. Overall, he proved to be less effective as a manager than his father. In particular, he lacked

15104-552: Was expected of the new camera. However, Paul Franke proposed a temporary suspension of further development work because of the catastrophic economic situation. Heidecke concurred, believing that better times lay ahead. The first prototype of the new camera, named the Rolleiflex , was finally completed in 1927; it was built for absolute reliability and featured a rigid, injection-moulded housing made of aluminium . Heidecke wanted to avoid conventional leather bellows for focusing

15232-413: Was originally developed and proposed to other manufacturers by the German shutter manufacturer Friedrich Deckel in the early 1950s. Combinations of shutter speed and relative aperture that resulted in the same exposure were said to have the same exposure value E v {\displaystyle E_{v}} , a base-2 logarithmic scale defined by When applied to the left-hand side of

15360-649: Was particularly well-suited to portrait photography . Meanwhile, plans for another model with a 150 mm lens were abandoned. The Wide Angle Rolleiflex (also known as the Rolleiwide ) with an f/4, 55 mm lens followed in 1961. It only remained in production until 1967, which today makes it one of the rarest Rolleiflex cameras – excluding special editions. Its main advantage lay in its ability to photograph large crowds at heavily attended events. Reinhold Heidecke kept on making new cameras right up until his death in 1960, although no one bothered to admonish him over

15488-448: Was relatively expensive at 435 DM. It featured an automatic exposure control system driven by a coupled selenium light meter which could select shutter speeds from 1/30 sec to 1/300 sec and apertures from f/3.5 to f/22. There were only two manual controls: one for focusing, the other for selecting either a shutter speed of 1/30 sec (for flash photography), or Brief (for long-exposure night photography ). Its successor,

15616-516: Was simple, because a change of 1 E v {\displaystyle E_{v}} corresponded to a change of 1 exposure step , i.e., either a halving or doubling of exposure. Starting 1954, the so-called Exposure Value Scale (EVS), originally known as Light Value Scale (LVS), was adopted by Rollei , Hasselblad , Voigtländer , Braun , Kodak , Seikosha , Aires , Konica , Olympus , Ricoh and others, introducing lenses with coupled shutters and apertures, such that, after setting

15744-415: Was so popular that it bred over 500 imitations, more than half of them from Japan . The factory grew rapidly; by 1956 – the year the millionth camera was sold – the workforce numbered 1600, and by 1957 the workforce had grown to 2000 employees. Hans Hass , the underwater diving pioneer, approached Franke & Heidecke to see if they could make him a special housing suitable for underwater photography . As

15872-576: Was sold back to its internal management in 1999. In 2002, it was bought by a Danish investment group, and renamed Rollei GmbH in 2004. In 2005/2006, the company headquarters moved to Berlin and the company was split into two different companies: Rollei GmbH in Berlin, owner of the Rollei brand and selling various OEM equipment, and Rollei Produktion GmbH in Braunschweig, an equipment factory which became Franke & Heidecke GmbH, Feinmechanik und Optik . Following another restructuring in 2007, Rollei

16000-510: Was split into three companies. Franke & Heidecke GmbH, Feinmechanik und Optik focused on the production of professional medium format cameras and slide projectors , while RCP-Technik GmbH & Co. KG in Hamburg was responsible for Rollei consumer products like re-branded compact digital cameras in the European market, and with the RCP Technik Verwaltungs GmbH owning the rights to

16128-438: Was still prone to failure. While it was no threat to the fully developed Rolleiflex to begin with, that situation changed when the legendary Hasselblad 500C featuring a Compur leaf shutter appeared in 1957. The management of Rollei under Horst Franke were caught napping, having failed to produce a camera that could match the latest Hasselblad. As a consequence, sales plummeted and the company got into financial difficulties. In

16256-439: Was the way forward, and both Leica and Wirgin (through their Edixa brand) produced similar designs. The Rollei 16 used special Super 16 film cartridges with a capacity of 18 frames. As no film manufacturer was interested in making this film format, Rollei had to manufacture the film itself. A roll of B/W film cost 5 DM, while slide film (available until 1981) cost 12.50 DM, including development. Loading

16384-452: Was working as a production manager at Voigtländer in Braunschweig around 1916, he got the idea to manufacture a new type of roll-film camera. However, the company rejected his proposal because they thought there would be problems keeping the film perfectly flat . Besides, their current camera range, which used conventional photographic plates , was selling well. Heidecke tried unsuccessfully to secure financing to start his own company, so, at

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