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21-654: The name Minolta was first used in 1932 on the 4.5×6 format Semi-Minolta using 120 film . The manufacturer was established in November 1928 by Kazuo Tashima  [ ja ] (1899-1985) as the Nichidoku Shashinki Shōten (Japan-German Camera Store) together with two Germans living in Japan, but reorganised as a joint stock company named the Molta Goshi Kaisha in the summer of 1931. It is likely that this inspired

42-496: A brief range of quite popular rangefinder models lasting until the end of the 1950s. In 1962 the company name was changed to Minolta Camera K.K. The Minolta SR-2 is well built and thoroughly constructed; including features that remained characteristic of the Minolta SLR camera range to follow until the advent of the auto focus cameras in the 1980s. The main features are a single stroke wind-on lever; an instant return mirror and

63-413: A film back magazine and this may end up on a frame; this is not a problem when 15 exposures are used as the gaps between exposed frames is larger, nor if the camera is not used intermittently. The 6×9 frame has the same aspect ratio as the standard 24×36 mm frame of 135 film . The 6×7 frame enlarges almost exactly to 8×10 inch paper, for which reason its proponents call it "ideal format". 6×4.5

84-411: A much wider flange, similar to the 116 spool, while the 117 spool's flange is slightly narrower than the 120. The 105 and 620 spools also have much thinner flanges than the 117 and 120 spools (0.635 mm (0.0250 in) vs. 1.524 mm (0.0600 in)); as a result, an unmodified 120 spool will not fit a camera designed for 105 film, such as a No. 1 Folding Pocket Kodak, as the overall length between

105-470: A red window. Also, since the film alone is thinner than a film with a backing paper, a special pressure plate may be required to achieve optimal focus if the film is registered against its back side. Some cameras capable of using both 120 and 220 film will have a two position adjustment of the pressure plate (e.g. the Pentax 6x7 , Mamiya C220 or Mamiya C330 ) while others will require different film backs e.g.

126-449: A sturdy three-pronged bayonet lens mount with an internal automatic aperture stop-down mechanism. This mount is the earliest example of a modern 35mm SLR bayonet lens mount , used throughout the entire lifespan of the Minolta manual focus camera area. The automatic aperture mechanism on this camera does not reopen the aperture after exposure, a feature at the time regarded as unnecessary, since

147-481: Is a point where light rays originating from a point on the object converge . Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle . This non-ideal focusing may be caused by aberrations of the imaging optics. Even in the absence of aberrations, the smallest possible blur circle is the Airy disc caused by diffraction from the optical system's aperture ; diffraction

168-492: Is readily available to both professionals and amateur enthusiasts. The 120 film format is a roll film which is nominally between 60.7 mm and 61.7 mm wide. Most modern films made today are roughly 61 mm (2.4 inches) wide. The film is held in an open spool originally made of wood with metal flanges, later with all-metal, and finally with all-plastic. The length of the film is nominally between 820 millimetres (32 in) and 850 millimetres (33 in), according to

189-472: Is sometimes defined using a " circle of confusion " criterion. A principal focus or focal point is a special focus: Diverging (negative) lenses and convex mirrors do not focus a collimated beam to a point. Instead, the focus is the point from which the light appears to be emanating, after it travels through the lens or reflects from the mirror. A convex parabolic mirror will reflect a beam of collimated light to make it appear as if it were radiating from

210-444: Is the smallest and least expensive roll-film frame size. The wide 6×12, 6×17, and 6×24 cm frames are produced by special-purpose panoramic cameras. Most of these cameras use lenses intended for large format cameras for simplicity of construction. Cameras using 120 film will often combine the numbers of the frame size in the name e.g. Pentax 6×7 (6×7), Fuji 617 (6×17), and many 645 s (6×4.5). The number '6' in general, and

231-449: Is the ultimate limit to the light focusing ability of any optical system. Aberrations tend to worsen as the aperture diameter increases, while the Airy circle is smallest for large apertures. An image, or image point or region, is in focus if light from object points is converged almost as much as possible in the image, and out of focus if light is not well converged. The border between these

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252-450: The Pentax 645 or Kowa Six . The specifications for 120 and 220 film are defined in the ISO 732 standard. Earlier editions of ISO 732 also provided international standards for the 127 and 620 film formats. 120 film allows several frame sizes. (cm) User selectable on newer cameras, if a roll is only partially used then a "kink" may appear in the film where the roll touches rollers in

273-481: The outside of the flanges is too long to fit the width of the film chamber. The 620 format was introduced by Kodak in 1931 as an intended alternative to 120. Although mostly used by Kodak cameras, it became very popular. The 620 format is essentially the same film on a thinner and narrower all-metal spool (the 120 spool core was made of wood at that time): Hence the 620 is sometimes referred to as "small hole" 6×6 or 6×9 as opposed to 120 "large hole". The 620 format

294-549: The ISO 732:2000 standard. However, some films may be as short as 760 millimetres (30 in). The film is attached to a piece of backing paper longer and slightly wider than the film. The backing paper protects the film while it is wound on the spool, with enough extra length to allow loading and unloading the roll in daylight without exposing any of the film. Frame number markings for three standard image formats (6×4.5, 6×6, and 6×9 [4:3, 1:1, and 2:3 aspect ratios]; see below) are printed on

315-484: The backing paper. The 220 format was introduced in 1965 and is the same width as 120 film, but with about double the length of film and thus twice the number of possible exposures per roll. Unlike 120 film, however, there is no backing paper behind the film itself, just a leader and a trailer. This results in a longer film on the same spool, but there are no printed frame numbers. Because of this, 220 film cannot be used in cameras that rely on reading frame numbers through

336-427: The darkened finder might indicate the camera not being made ready for the next exposure. The SR-2 was joined a year later by the budget model SR-1, and was replaced in 1960 by the improved SR-3. This range was complemented by an increasing selection of high quality Minolta SR mount Rokkor lenses, within a few years ranging from 35mm to 600mm, and an RF 800mm f8 mirror lens in 1960, some of these even multicoated from

357-409: The focal point, or conversely, reflect rays directed toward the focus as a collimated beam. A convex elliptical mirror will reflect light directed towards one focus as if it were radiating from the other focus, both of which are behind the mirror. A convex hyperbolic mirror will reflect rays emanating from the focal point in front of the mirror as if they were emanating from the focal point behind

378-537: The name Minolta that later became a registered trade mark. However, in 1937 the company was reorganised as the Chiyoda Kogaku Seikō KK , CHIYOKO for short. Chiyoda Kogaku manufactured leaf shutters and photographic lenses, as well as melting their own optical glasses , an achievement very few camera makers ever have matched. In 1947, the Minolta-35 was launched as the company's first 35mm camera, resulting in

399-514: The very start. The characteristic features of the Minolta SR-2 The Rokkor lenses for the SR-2 120 film 120 is a film format for still photography introduced by Kodak for their Brownie No. 2 in 1901. It was originally intended for amateur photography but was later superseded in this role by 135 film . 120 film survives to this day as the only medium format film that

420-495: The word 'six' are also commonly used in naming cameras e.g. Kiev 60 and Pentacon Six . The 105 format was introduced by Kodak in 1898 for their first folding camera and was the original 6×9 cm format roll film. The 117 format was introduced by Kodak in 1900 for their first Brownie camera, the No.1 Brownie, 6×6 cm format. These formats used the same width film as 120 film, but with slightly different spools. The 105 spool has

441-414: Was discontinued by Kodak in 1995, but it is possible to rewind 120 film onto a 620 spool in the darkroom for use in 620 cameras. According to Kodak, the narrower metal spool allowed building smaller cameras. Nonetheless the 120 format cast-metal bodied Voigtländer Perkeo remains smaller than any 620 format camera. Focus (optics) In geometrical optics , a focus , also called an image point ,

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