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A camera is a device used to capture images, either as still photographs or
as sequences of moving images (movies or videos). The term as well as the
modern-day camera evolved from the Latin camera obscura for "dark chamber" for
an early mechanism of projecting images where an entire room functioned as a
real-time imaging system.
Cameras may work with the light of the visible spectrum or with other portions
of the electromagnetic spectrum. A camera generally consists of an enclosed
hollow with an opening (aperture) at one end for light to enter, and a recording
or viewing surface for capturing the light at the other end. Most cameras have a
lens positioned in front of the camera's opening to gather the incoming light
and focus all or part of the image on the recording surface. The diameter of the
aperture is often controlled by a diaphragm mechanism, but some cameras have a
fixed-size aperture.
Exposure control
The size of the aperture and the brightness of the scene control the amount of
light that enters the camera during a period of time, and the shutter controls
the length of time that the light hits the recording surface. Equivalent
exposures can be made with a larger aperture and a faster shutter speed or a
corresponding smaller aperture and with the shutter speed slowed down.
Focus
Due to the optical properties of photographic lenses, only objects within a
certain range of distances from the camera will be reproduced clearly. The
process of adjusting this range is known as changing the camera's focus. There
are various ways of focusing a camera accurately. The simplest cameras have
fixed focus and use a small aperture and wide-angle lens to ensure that
everything within a certain range of distance from the lens, usually around 3
metres (10 ft) to infinity, is in reasonable focus. Fixed focus cameras are
usually inexpensive types, such as single-use cameras. The camera can also have
a limited focusing range or scale-focus that is indicated on the camera body.
The user will guess or calculate the distance to the subject and adjust the
focus accordingly. On some cameras this is indicated by symbols
(head-and-shoulders; two people standing upright; one tree; mountains).
Rangefinder cameras allow the distance to objects to be measured by means of a
coupled parallax unit on top of the camera, allowing the focus to be set with
accuracy. Single-lens reflex cameras allow the photographer to determine the
focus and composition visually using the objective lens and a moving mirror to
project the image onto a ground glass or plastic micro-prism screen. Twin-lens
reflex cameras use an objective lens and a focusing lens unit (usually identical
to the objective lens) in a parallel body for composition and focusing. View
cameras use a ground glass screen which is removed and replaced by either a
photographic plate or a reusable holder containing sheet film before exposure.
Modern cameras often offer "auto-focus" systems to focus the camera
automatically by a variety of methods.
Image capture
Traditional cameras capture light onto photographic film or photographic plate.
Video and digital cameras use electronics, usually a charge coupled device (CCD)
or sometimes a CMOS sensor to capture images which can be transferred or stored
in tape or computer memory inside the camera for later playback or processing.
Cameras that capture many images in sequence are known as movie cameras or as
ciné cameras in Europe; those designed for single images are still cameras.
However these categories overlap, as still cameras are often used to capture
moving images in special effects work and modern digital cameras are often able
to trivially switch between still and motion recording modes. A video camera is
a category of movie camera that captures images electronically (either using
analogue or digital technology).
A Stereo camera can take photographs that appear "three-dimensional" by taking
two different photographs that can be combined to create the illusion of depth
in the composite image. Stereo cameras for making 3D prints or slides have two
lenses side by side. Stereo cameras for making lenticular prints have 3, 4, 5,
or even more lenses. Some film cameras feature date imprinting devices that can
print a date on the negative itself.
History
History of the camera
The forerunner to the camera was the camera obscura. The camera obscura is an
instrument consisting of a darkened chamber or box, into which light is admitted
through a double convex lens, forming an image of external objects on a surface
of paper or glass, etc., placed at the focus of the lens. The camera obscura was
first invented by the Iraqi scientist Ibn al-Haytham (Alhazen) as described in
his Book of Optics (1015-1021). English scientist Robert Boyle and his assistant
Robert Hooke later developed a portable camera obscura in the 1660s.
The first camera that was small and portable enough to be practical for
photography was built by Johann Zahn in 1685, though it would be almost 150
years before technology caught up to the point where this was practical. Early
photographic cameras were essentially similar to Zahn's model, though usually
with the addition of sliding boxes for focusing. Before each exposure, a
sensitized plate would be inserted in front of the viewing screen to record the
image. Jacques Daguerre's popular daguerreotype process utilized copper plates,
while the calotype process invented by William Fox Talbot recorded images on
paper.
The first permanent photograph was made in 1826 by Joseph Nicéphore Niépce using
a sliding wooden box camera made by Charles and Vincent Chevalier in Paris.
Niépce built on a discovery by Johann Heinrich Schultz (1724): a silver and
chalk mixture darkens under exposure to light. However, while this was the birth
of photography, the camera itself can be traced back much further. Before the
invention of photography, there was no way to preserve the images produced by
these cameras apart from manually tracing them.
The development of the collodion wet plate process by Frederick Scott Archer in
1850 cut exposure times dramatically, but required photographers to prepare and
develop their glass plates on the spot, usually in a mobile darkroom. Despite
their complexity, the wet-plate ambrotype and tintype processes were in
widespread use in the latter half of the 19th century. Wet plate cameras were
little different from previous designs, though there were some models, such as
the sophisticated Dubroni of 1864, where the sensitizing and developing of the
plates could be carried out inside the camera itself rather than in a separate
darkroom. Other cameras were fitted with multiple lenses for making cartes de
visite. It was during the wet plate era that the use of bellows for focusing
became widespread.
The first colour photograph was made by James Clerk Maxwell, with the help of
Thomas Sutton, in 1861.
Camera brands
* Agfa
* ARCA-Swiss
* Agilux
* Alpa
* Argus
* Asahiflex
* Balda
* Bolex
* Braun (company)
* Bronica
* Burke & James
* Cambo
* Canon
* Casio
* Contax
* Corfield
* Coronet
* Ducati
* Diana camera
* Ebony
* Edixa
* Ensign
* Exakta
* FED
* Folmer & Schwing
* Fujifilm
* Fujica
* Gami
* Gateway, Inc.
* Graflex
* Hasselblad
* Hewlett Packard
* Holga
* Honeywell
* Horseman
* Ilford
* Imaging Solutions Group (ISG)
* Kodak
* Konica
* Leica
* Linhof
* Lomo
* Lumix
* Minolta
* Mamiya
* Minox
* MPP
* Miranda
* Mustek
* Newman & Guardia
* Nikon
* Olympus
* Oregon Scientific
* Osaka
* Panasonic
* Pentax
* Petri
* Polaroid
* Plaubel Makina
* Praktica
* Promaster
* Reid
* Ricoh
* Rollei
* Samsung
* SatuGO
* Seagull
A rangefinder camera is a camera fitted with a rangefinder: a range-finding
focusing mechanism allowing the photographer to measure the subject distance and
take photographs that are in sharp focus. Most varieties of rangefinder show two
images of the same subject, one of which moves when a calibrated wheel is
turned; when the two images coincide and fuse into one, the distance can be read
off the wheel. Older, non-coupled rangefinder cameras display the focusing
distance and require the photographer to transfer the value to the lens focusing
ring; cameras without built-in rangefinders could have an external rangefinder
fitted into the accessory shoe. Earlier cameras of this type had separate
viewfinder and rangefinder windows; later the rangefinder was incorporated into
the viewfinder. More modern designs have rangefinders coupled to the focussing
mechanism, so that the lens is focussed correctly when the rangefinder images
fuse.
Most digital cameras, and some film cameras, measure distance using
electroacoustic or electronic means and focus automatically (autofocus);
however, it is not customary to speak of this functionality as a rangefinder.
History
The first rangefinders, sometimes called "telemeters", appeared in the
nineteenth century; the first rangefinder camera to be marketed was the 3A Kodak
Autographic Special of 1916; the rangefinder was coupled.
Not itself a rangefinder camera, the Leica I of 1925 had popularized the use of
accessory rangefinders. The Leica II and Zeiss Contax I, both of 1932, were
great successes as 35mm rangefinder cameras. The Contax II (1936) integrated the
rangefinder in the center of the viewfinder.
Rangefinder cameras were common from the 1930s to the 1970s, but the more
advanced models lost ground to single-lens reflex (SLR) cameras.
Rangefinder cameras have been made in all sizes and all film formats over the
years, from 35mm through medium format (rollfilm) to large-format press cameras.
Until the mid-1950s most were generally fitted to more expensive models of
cameras. Folding bellows rollfilm cameras, such as the Balda Super Baldax or
Mess Baldix, the Kodak Retina II, IIa, IIc, IIIc, and IIIC cameras and the Hans
Porst Hapo 66e (a cheaper version of the Balda Mess Baldix), were often fitted
with rangefinders.
The best-known rangefinder cameras take 35mm film, use focal plane shutters, and
have interchangeable lenses. These are Leica screwmount (also known as M39)
cameras developed for lens manufacturer Leitz Wetzlar by Oscar Barnack (which
gave rise to very many imitations and derivatives), Contax cameras manufactured
for Carl Zeiss Optics by camera subsidiary Zeiss-Ikon and, after Germany's
defeat in World War II, produced again and then developed as the Ukrainian
Kiev), Nikon S-series cameras from 1951-1962 (with design inspired by the Contax
and function by the Leica), and Leica M-series cameras.
The Nikon rangefinder cameras were "discovered" in 1950 by Life magazine
photographer David Douglas Duncan, who covered the Korean War. Because of the
high optical quality of the Nikon lenses, Nikon rangefinder cameras became the
American standard for photojournalists in the 1950s. Canon manufactured several
models from the 1930s until the 1960s; models from 1946 onwards were more or
less compatible with the Leica thread mount. (From late 1951 they were
completely compatible; the 7 and 7s had a bayonet mount for the 50 mm f/0.95
lens in addition to the thread mount for other lenses.)
Other such cameras include the Casca (Steinheil, West Germany, 1948), Detrola
400 (USA, 1940–41), Ektra (Kodak, USA, 1941–8), Foca (OPL, France, 1947–63),
Foton (Bell & Howell, USA, 1948), Opema II (Meopta, Czechoslovakia, 1955–60),
Perfex (USA, 1938–49), Robot Royal (Robot-Berning, West Germany, 1955–76), and
Witness (Ilford, Britain, 1953). Among the longer lasting marques, all but the
Leica M succumbed in the marketplace to pressure from SLRs. The most recent in
the M-series are the M7, the first of the series to feature automatic exposure
and an electronic shutter; and the all-mechanical MP, an updated M6 with an
M3-style rewind knob; and the new M8, Leica's first digital rangefinder.
In the United States the dependable and cheap Argus (especially the ubiquitous
C-3 "Brick") was far and away the most popular 35mm rangefinder, with millions
sold.
Interchangeable-lens rangefinder cameras with focal-plane shutters are greatly
outnumbered by fixed-lens leaf-shutter rangefinder cameras. The most popular
design in the '50s were folding designs like the Kodak Retina and the Zeiss
Contessa.
In the 1960s many fixed-lens 35mm rangefinder cameras for the amateur market
were produced by several manufacturers, mainly Japanese, including Canon, Fujica,
Konica, Mamiya, Minolta, Olympus, Ricoh, and Yashica. Distributors such as
Vivitar and Revue often sold rebranded versions of these cameras. While designed
to be compact like the Leica, they were much less expensive. Many of them, such
as the Minolta 7sII and the Vivitar 35ES, were fitted with high-speed, extremely
high quality optics. Though eventually replaced in the market with newer compact
autofocus cameras, many of these older rangefinders continue to operate, having
outlived most of their newer (and less well-constructed) successors.
Starting with a camera made by the small Japanese company Yasuhara in the 1990s,
there has been something of a revival of rangefinder cameras. Aside from the
Leica M series, rangefinder models from this period include the Konica Hexar RF,
Cosina, who makes the Voigtl?nder Bessa T/R/R2/R3/R4 (the last three are made in
both manual or aperture automatic version, which use respectly the "m" or "a"
sign in model), and the Hasselblad Xpan/Xpan 2. Zeiss has a new model called the
Zeiss Ikon, also made by Cosina, while Nikon has also produced expensive limited
editions of its S3 and SP rangefinders to satisfy the demands of collectors and
aficionados. Cameras from the former Soviet Union — the Zorki and FED, based on
the screwmount Leica, and the Kiev — are plentiful in the used market.
Medium-format (rollfilm) rangefinder cameras continue to be produced. Recent
models include the Mamiya 6 and 7I/7II, the Bronica RF645 and the Fuji G, GS and
GSW series.
In 1994, Contax introduced an autofocus rangefinder camera, the Contax G.
Digital rangefinder
Digital imaging technology was applied to rangefinder cameras for the first time
in 2004, with the introduction of the Epson R-D1 the first ever digital
rangefinder camera, which was made as a result of collaboration between Epson
and Cosina. The latter has also obtained rights to the name Voigtl?nder and
currently manufactures rangefinder lenses with that name. The R-D1 and later
R-D1s use Leica M-mount lenses, or earlier Leica screw mount lenses with an
adapter. Leica released its first digital rangefinder camera, the Leica M8, in
2006. As of November 2007 no other digital rangefinder cameras have been made.
All three models take the same rangefinder interchangeable lenses used on their
film counterparts. They are all expensive compared to average dSLRs, and do not
support live preview on their LCD displays.
The Epson R-D1 with a Leica lens
The Leica M8
Pros and cons
SLRs are usually marketed as technically more advanced than rangefinder cameras:
they normally have more system options, which tends to make them more
profitable. Sales appeal and profits aside, SLRs display the image through the
camera's lens, allowing any lens to be used without a special viewfinder for it,
and eliminating parallax errors at any subject distance allowing macro
photography.
The viewfinder of a rangefinder camera is necessarily offset from the taking
lens, so that the image shown is not exactly what will be recorded on the film;
this parallax error is negligible at large subject distances, and increases as
the distance decreases. More advanced rangefinder cameras project into the
viewfinder a brightline frame that moves as the lens is focussed, correcting
parallax error down to the minimum distance at which the rangefinder functions
(not as close as the minimum focusing distance of an SLR lens with the same
focal length and film format). The angle of view of a given lens also changes
with distance, and the brightline frames in the finders of a few cameras
(including some leaf-shutter 35mm Konicas, starting with the Konica IIIA of
1958) automatically adjust for this as well. For extreme close-up photography,
the rangefinder camera is awkward to use, as the viewfinder becomes useless.
The only true zoom lenses for rangefinder cameras is the Contax G2 Carl Zeiss
35-70mm Vario-Sonnar T* Lens with built-in zoom viewfinder , though a very few
lenses such as the Konica M-Hexanon Dual or Leica Tri-Elmar let the user select
among two or three focal lengths; the viewfinder must be designed to work with
all focal lengths of any lens used.
Rangefinder cameras have advantages over SLRs for certain applications. Since
there is no moving mirror, as used in SLRs, there is no momentary blackout of
the subject being photographed, the camera is often quieter (particularly with
leaf shutters) and usually smaller and less obtrusive. These qualities make
rangefinders more attractive for theater photography, some portrait photography,
action-grabbing candid shots and street photography, and where portability
matters. The lack of a mirror allows lenses to project deep into the camera
body, making high-quality wide-angle lenses easier to design. (The Voigtl?nder
12mm lens was the widest-angle rectilinear lens in general production for a long
time, with a 121 degree angle of view, but recently the Sigma 12-24mm for SLR
cameras has matched its angle with 122 degrees.) Rangefinder focusing is more
accurate for wide-angle lenses (whereas an SLR is more accurate with telephoto
lenses). The rangefinder may become misaligned, leading to incorrect focussing,
a problem absent from SLRs.
If filters which absorb much light or change the colour of the image are used it
is difficult to compose, view, and focus on an SLR, but the image through a
viewfinder is unaffected. On the other hand some filters, such as graduated
filters and polarizers, are best used with SLRs as the effect they create can be
viewed directly.
The single-lens reflex (SLR) camera utilizes an automatic moving mirror system
which permits the photographer to see exactly what will be captured by the film
or digital imaging system, as opposed to non-SLR cameras where the view through
the viewfinder could be significantly different from what was captured on film.
Prior to the development of SLR, all cameras with viewfinders had two optical
light paths: one path through the lens to the film, and another path positioned
slightly off to the side seen by the photographer. Because the viewfinder and
the film lens cannot share the same optical path, the viewfinder is aimed to
intersect with the film lens at a fixed point somewhere in front of the camera.
This is more or less helpful for pictures taken at a middle or longer distance
but a close-up shot framed in the viewfinder will not look the same as the film
image. Moreover, focusing the lens of a non-SLR camera when it is opened to
wider apertures (such as in low light or whilst using low speed film) is not
easy.
SLR cameras permit direct viewing using a pentaprism situated above the optical
path through the lens to the film plane. Light is reflected by a movable mirror
upwards into the pentaprism where it is reflected several times until it aligns
with the viewfinder. When the shutter is released, the mirror moves out of the
light path and the light shines directly onto the film, or in the case of a DSLR,
the CCD or CMOS imaging sensor.
The focus can be adjusted manually by the photographer or automatically by the
autofocus system. The viewfinder can include a matte focusing screen located
just above the mirror system to diffuse the light. This system permits accurate
viewing, composing and focusing, especially useful with interchangeable lenses.
Up until the 1990s, SLR was the most advanced photographic preview system
available. But the recent development and refinement of digital imaging
technology with an on-camera live LCD preview screen has overshadowed SLR's
popularity. Nearly all inexpensive compact digital cameras now include an LCD
preview screen allowing the photographer to see exactly what the CCD is
capturing. However, SLR is still popular in high-end and professional cameras,
because the pixel resolution, contrast ratio, and color gamut of an LCD preview
screen cannot compete with the clarity and shadow detail of a direct-viewed
optical SLR viewfinder.
Optical components of an SLR camera
Cross-section view of SLR system: 1 - Front-mount Lens (4 element Tessar design)
2 - Reflex Mirror at 45 degree angle 3 - Focal Plane Shutter 4 - 35 mm Film or
Sensor 5 - Focusing Screen 6 - Condenser Lens 7 - Optical Glass Pentaprism (or
Pentamirror) 8 - Eyepiece (can have diopter correction ability)
Cross-section view of SLR system:
1 - Front-mount Lens (4 element Tessar design)
2 - Reflex Mirror at 45 degree angle
3 - Focal Plane Shutter
4 - 35 mm Film or Sensor
5 - Focusing Screen
6 - Condenser Lens
7 - Optical Glass Pentaprism (or Pentamirror)
8 - Eyepiece (can have diopter correction ability)
A cross-section (or 'side-view') of the optical components of a typical SLR
camera shows how the light passes through the lens assembly (1), is reflected by
the mirror (2) and is projected on the matte focusing screen (5). Via a
condensing lens (6) and internal reflections in the roof pentaprism (7) the
image appears in the eyepiece (8). When an image is taken, the mirror moves
upwards from its critical 45 degree angle in the direction of the arrow, the
focal plane shutter (3) opens, and the image is projected onto the film or
sensor (4) in exactly the same manner as on the focusing screen.
This feature distinguishes SLRs from other cameras as, the photographer sees the
image composed exactly as it will be captured on the film or sensor (see
Advantages below).
Pentaprisms and penta-mirrors
Most SLRs use a roof pentaprism or penta-mirror to direct the light to the
eyepiece, but there are other finder viewing capabilities, such as the
waist-level finder, the interchangeable sports finders used on the Canon F1, F1n
and new F1; the Nikon F, F2, F3, F4 and F5; and the Pentax LX
Another prism design was the porro prism system used in the Olympus Pen F, the
Pen FT, the Pen FV half-frame 35 mm SLR cameras. This was later utilized on the
digital Olympus EVOLT E-300 and E-330 DSLR cameras.
Lastly, a photographer can also purchase a right-angle finder which slips onto
the eyepiece of most SLR's and D-SLR's and allows viewing sans a waist-level
finder. There is also a finder which provides EVF remote capability.
Shutter mechanisms
Focal plane shutters
Almost all contemporary SLRs use a focal plane shutter located in front of the
film plane, which prevents the light from reaching the film even if the lens is
removed, except when the shutter is actually released during the exposure. There
are various designs for focal plane shutters. Typical focal plane shutters
designed in the fifties and continuing through part of the 1990's consisted of
cloth material with two curtains: an opening shutter curtain followed by a
closing shutter curtain. During fast shutter speeds, the focal plane shutter
would form a 'slit' whereby the second shutter curtain was closely following the
first opening shutter curtain to produce a narrow, vertical opening, with the
shutter slit moving horizontally. The slit would get narrower as shutter speeds
were increased.
Other focal plane shutter designs such as the Copal, travelled vertically. These
were constructed of titanium foil and were metal-bladed (resembling something
like a 'venetian blind'), and resulted in faster flash synchronization. Certain
horizontally travelling focal plane shutters were also constructed of titanium
foil as is the case with the Nikon F, F2, F3, F4, F5 and F6 35mm SLR cameras,
and the Canon F-1 camera series. A unique focal plane shutter design was the
rotary shutter used in the Olympus Pen half-frame 35 mm SLR camera system. This
shutter system was also titanium foil but consisted of one piece of metal with a
fixed opening, and this shutter system allowed electronic flash (EF)
synchronization up to and including its top shutter speed of 1/500 of a second,
thereby rivaling leaf-shutter EF capabilities.
Leaf shutters - Two Types
Another shutter system is the leaf shutter, whereby the shutter is constructed
of diaphragm-like blades and can be situated either between the lens or behind
the lens. If the shutter is part of a lens assembly some other mechanism is
required to ensure that no light reaches the film between exposures. The leaf
shutter can either be situated between the lens or behind the lens assembly.
An example of a behind-the-lens leaf shutter is found in the 35 mm SLR's
produced by Kodak, with their Retina Reflex camera line; Topcon, with their Auto
100; and Kowa with their SE-R and SET-R reflexes.
A primary example of a medium-format SLR with a between-the-lens leaf shutter
system would be Hasselblad, with their 500C, 500CM, 500 EL-M (a motorized
Hasselblad) and other models (producing a 2 1/4" square negative {or 6 cm x 6cm
metric}). Hasselblads use an auxiliary shutter blind situated behind the lens
mount and the mirror system to prevent the fogging of film.
Other medium-format SLRs also using leaf shutters include the now discontinued
Zenza-Bronica camera system lines such as the Bronica ETRs, the ETRs'i (both
producing a 6 cm. x 4.5 cm. image), the SQ and the SQ-AI (producing a 2 1/4" or
6 x 6 cm. image like the Hasselblad), and the Zenza-Bronica G system (2 1/4" x 2
3/4" inch or 6 cm. x 7 cm.). Certain Mamiya medium-format SLRs, discontinued
camera systems such as the Kowa 6 and a few other camera models also used
between-the-lens leaf shutters in their lens systems.
Thus, anytime a photographer purchased a lens for the Hasselblad, with the
exception of the older Hasselblad 1000f and other focal-plane shutter
Hasselblads; or the Zenza-Bronica ETR, ETR-S, ETR-Si, the SQ, the SQ-Ai, the
SQ-B, and the G series (with the exception of older Bronica cameras such as the
Bronica Deluxe, the Bronica S, the Bronica S2), or the bigger system Mamiya
RB-67, RB-67 Pro, RB-67 Pro S (mechanical) and RZ (electronically controlled
shutter) cameras, that lens included a leaf shutter in its lens mount.
Because leaf shutters synchronized electronic flash at all shutter speeds
especially at fast shutter speeds of 1/500 of a second or faster, cameras
utilizing leaf shutters were more desired by studio photographers who used
sophisticated studio electronic flash systems.
Some manufacturers of medium-format 2 1/4" SLR cameras also made leaf-shutter
lenses for their focal plane shutter models. Rollei made at least two such
lenses for their Rolleiflex SL-66 medium format, 2 1/4" camera, which was a
focal-plane shutter SLR. Rollei later switched to a camera system of
leaf-shutter design, (i.e., the 6006 and 6008 reflexes to name a few) and their
current medium-format SLR's are now all of the between-the-lens shutter design.
Rotary shutter
One unusual design, the Olympus Pen half-frame 35 mm SLR system, manufactured by
Olympus in Japan, used a rotary focal plane shutter mechanism which was
extremely simple and elegant in design, and enabled the photographer to
synchronize electronic flash at all shutter speeds, including the shutter's
limit to 1/500 of a second. The camera started out meterless with the
introduction of the Olympus Pen F; this camera required a two-stroke advance of
the advance lever. The later models, the Olympus Pen FT and the Olympus Pen FV
only required a single stroke of the film advance lever to position the film to
the next frame. The Olympus Pen FT has a behind-the-lens metering system and was
composed of a number of impressive optics from a 20 mm lens up to an 800 mm
catadioptric (mirror) telephoto lens. The system included 'fast' lenses such as
the 38mm f/1.8 Zuiko, the 40mm f/1.4 Zuiko and the 42mm f/1.2 Zuiko, all
considered 'normal' lenses for this format. Olympus also made a 38mm f/3.5 macro
lens, and a bellows extension attachment. There were also various lens adapters
and other accessories for this camera.
As a further, minor note on rotary shutters, only one other 35 mm camera system
used a rotary shutter, and this camera system was the Robot Royal cameras, most
of which were rangefinder 35 mm cameras. Some of these cameras were full-frame;
some were half-frame, and at least one Robot camera produced an unusual
square-sized image on the 35 mm frame.
Further developments
Since the technology became widespread in the 1970s, SLRs have become the main
photographic instrument used by dedicated amateur photographers and
professionals. Some photographers of static subjects (such as architecture,
landscape, and some commercial subjects), however, prefer view cameras because
of the capability to control perspective. With a triple-extension bellows 4" x
5" camera such as the Linhof SuperTechnika V, the photographer can correct
certain distortions such as 'keystoning', where the image 'lines' converge
(i.e., photographing a building by pointing a typical camera upward to include
the top of the building). Perspective correction lenses are available in the 35
mm and medium formats to correct this distortion with film cameras, and it can
also be corrected after the fact with photo software when using digital cameras.
The photographer can also extend the bellows to its full length, tilt the front
standard and perform photomacrography (commonly known as 'macro photography'),
producing a sharp image with depth-of-field without stopping down the lens
diaphgram.
History
M History of the single-lens reflex camera
The (Pentax) Asahiflex
The 35 mm film-based Nikon F
Olympus The 35 mm film-based Olympus OM-2, which was the first SLR to measure
light for electronic flash off of the shutter curtain.
Two Classic 35 mm SLR film cameras: the Canon AE-1 and the Minolta X-700
Nikon F5 professional SLR
Large format SLR cameras were probably first sold in 1884. The Ihagee
Kine-Exakta was the first 35 mm SLR and it was truly influential. Further Exakta
models, all with waist-level finders, were produced up to and during World War
II. Another ancestor of the modern SLR camera was the Swiss-made Alpa, which was
innovative, and influenced the later Japanese cameras. The first eye-level LSR
viewfinder was patented in Hungary on August 23, 1943 by Jen? Dulovits, who then
designed the first 35 mm camera with one, the Duflex, which used a system of
mirrors to provide a laterally correct, upright image in the eye-level
viewfinder. The Duflex, which went into serial production in 1948, was also the
world's first SLR with an instant-return (a.k.a. autoreturn) mirror.
The first commercially produced SLR that employed a roof pentaprism was the East
German Contax S, announced on May 20, 1949.
The Japanese adopted and further developed the SLR. In 1952, Asahi developed the
Asahiflex and in 1954, the Asahiflex IIB. In 1957, the Asahi Pentax combined the
fixed pentaprism and the right-hand thumb wind lever. Nikon, Canon and Yashica
introduced their first SLRs in 1959 (the F, Canonflex, and Pentamatic,
respectively).
Through-the-lens light metering (also known as "behind-the-lens metering")
As a small matter of history, the first 35 mm camera (non-SLR) to feature
through the lens light metering may have been Nikon, with a prototype
rangefinder camera, the SPX. According to the below website, the camera used
Nikon 'S' type rangefinder lenses (See website: http://www.cameraquest.com/nrfstory.htm).
In the SLR design scheme, there were various placements made for the metering
cells, all of which utilized CdS (Cadmium sulfide) photocells. The cells were
either located in the pentaprism housing, where they metered light transmitted
through the focusing screen; underneath the reflex mirror glass itself, which
was Topcon's design; or in front of the shutter mechanism, which was the design
used by Canon with their Canon Pellix.
Pentax was the first manufacturer to produce and show the first working
prototype 35 mm behind-the-lens metering SLR camera, which they named the Pentax
Spotmatic. The camera was first shown at a Photokina show circa 1960-1961.
Later, Through-the-lens (TTL) light metering SLRs were introduced to the
photographic market in the early 1960s, starting with the 1963 production model
Topcon RE Super which metered the light directly from a CdS metering system
etched under the mirror/glass assembly. This system metered the light using an
average metering system. Approximately one year later, in 1964, a production
model of the Pentax Spotmatic was shown whose CdS light meter cells were housed
in the pentaprism housing, reading the light coming upwards through the focusing
screen. Pentax had reverted their original spot-metering design to an average
metering scheme.
Mamiya Sekor came out with cameras such as the Mamiya Sekor TL and various other
versions. Yashica introduced the TL Super. Both of these cameras used M42 screw
thread lenses as did the Pentax Spotmatic. Later on Fujica introduced their
ST-701, then ST-801 and ST-901 cameras. The ST-701 was the first SLR to use a
silicon cell photodiode, which was more sensitive than CdS and was immune to the
memory effect that the CdS cell suffered from in bright sunlight. Gradually,
other 35 mm SLR camera manufacturers changed their behind-the-lens meters from
CdS cells to Silicon Diode photocells.
Other manufacturers responded and introduced their own behind-the-lens metering
cameras. Nikon and Miranda, at first, simply upgraded their interchangeable
pentaprisms to include behind-the-lens metering (for Nikon F, and Miranda D, F,
Fv and G models) and these manufacturers also bought out other camera models
with built-in behind-the-lens metering capability, such as the Nikkormat FT and
the Miranda Sensorex (which used an external coupling diaphragm). Minolta
introduced the SRT-101, which used Minolta's proprietary system which they
referred to as "CLC", which was an acronym for "contrast light compensation",
which metered differently from an average metering behind-the-lens camera.
Some German manufacturers also introduced cameras such as the Zeiss Ikon
Contarex SE, which was the only 35 mm SLR to use interchangeable film backs.
Inexpensive leaf-shutter cameras also benefited from behind-the-lens metering
as, Topcon introduced the Auto 100 with front-mount interchangeable lenses
designed only for that camera, and one of the Zeiss Ikon Contaflex leaf shutter
cameras. Kowa manufactured their SET-R which had similar specifications.
Within months, manufacturers decided to bring out models that provided limited
area metering, such as Nikon's Photomic Tn finder, which concentrated 60% of the
CdS cells sensitivity on the inner circle of the focusing screen and 30% on the
surrounding area. Canon used spot metering in the unusual Canon Pellix camera,
which also had a stationary mirror system that allowed approximately 70% of the
light to travel to the film plane and 30% to the photographer's eye. This
system, unfortunately, degraded the native resolution of the attached lens and
provided less illumination to the eyepiece. It did have the advantage of having
less vibration than other SLR cameras but not sufficient enough to attract
enough professionals to the camera.
Semi-automatic exposure capabilities
While auto-exposure was commonly used in the early 1960s with various 35 mm
fixed lens rangefinder cameras such as the Konica Auto 'S', and other cameras
such as the Polaroid Land cameras whose early models used selenium cell meters,
auto-exposure for interchangeable lens SLR's was a feature that was largely
absent, except for a few early leaf-shutter SLR's such as the Kowa SE-R and
Topcon Auto 100.
The types of automation found in some of these cameras consisted of the simple
programmed shutter, whereby the camera's metering system would select a
mechanically-set series of apertures with shutter speeds, one setting of which
would be sufficient for the correct exposure. In the case of the above-mentioned
Kowa and Topcon, automation was semi-automatic, where the camera's CDs meter
would select the correct aperture only.
Autoexposure, technically known as semi-automatic exposure, where the camera's
metering system chooses either the shutter speed or the aperture, was finally
introduced by the Savoyflex and popularized by Konishiroku in the 1965 Konica
Auto-Reflex. This camera was of the 'shutter-priority' type automation, which
meant that the camera selected the correct aperture automatically. This model
also had the interesting ability to photograph in 35 mm full-frames or
half-frames, all selected by a lever.
Other SLR's soon followed, but because of limitations with their lens mounts,
the manufacturers of these cameras had to choose 'aperture-priority' automation,
where the camera's metering system selects the correct shutter speed. As one
example, Pentax introduced the Electro Spotmatic, which was able to use the then
considerable bulk of 42 mm screw-mount lenses produced by various manufacturers.
Yashica, another screw-mount camera manufacturer, soon followed.
Canon, which produced the FD lens mount (known as the breech-mount; a unique
lens mounting system that combines the advantages of screw-mount and
bayonet-mount) introduced their shutter priority 35 mm SLR, the Canon EF in 1976
or so. This camera's build quality was almost the equal of their flagship
camera, the Canon F1, and featured a copal-square vertically-travelling focal
plane shutter which could synchronize electronic flash at shutter speeds up to
and including 1/125 of a second, thus making this a good second-body camera for
the professional photographer.
Nikon at first, produced an aperture-priority camera, but later made subtle
changes on the inside of their bayonet mount and soon, shutter-priority
automation was achieved.
Full Program Auto-Exposure
Minolta XD-11 (also XD-7 and XD)
Type 35 mm SLR
Lens mount Minolta MD mount
Focus Manual focus SLR
Exposure Shutter and Aperture priority autoexposure
Flash Hot shoe only; no PC connector
Dimensions 51 x 86 x 136 mm, 560 g
Full-program auto-exposure soon followed with the advent of the Minolta XD-11.
This SLR had a 'P' mode on the shutter speed dial, and a lock on the aperture
ring to allow the lens to be put on 'Auto' mode. Other manufacturers soon
followed with Nikon introducing the FA, Canon introducing the A1, and Pentax
introducing the Super Program. Olympus, however, continued with
'aperture-priority' automation in their OM system line.
The 1970s and 1980s saw steadily increasing use of electronics, automation, and
miniaturization, including integrated motor driven film advance with the Konica
FS-1 in 1979, and motor rewind functions.
Autofocus
The first phase detection SLR TTL autofocus 35 mm SLR was 1981's Pentax ME-F.
The Minolta Maxxum 7000, released in 1985, was the first 35 mm SLR with
integrated motorized autofocus and film-advance winder, which became the
standard configuration for SLR cameras from then on. This development had
significant impact on the photographic industry.
Some manufacturers discarded their existing lens systems to compete with other
manufacturer's autofocus capability in their new cameras. This was the case for
Canon, with its new EOS lens line. Other manufacturers chose to adapt their
existing lens systems for autofocus capability, as was the case with Nikon and
Pentax. Still some manufacturers, notably Leica with its R-system lenses, and
Contax with its Zeiss lenses, decided to keep their lens mounts non-autofocus.
Before the Contax camera and lens line was totally discontinued, Contax did come
out with autofocus and digital camera capability, evidenced in the Contax
N-Digital. Unfortunately this model was too late and too expensive for
competition with other camera manufacturers. The Contax N-digital was the last
Contax to use that maker's lens system, and the camera, while having impressive
features such as a full-frame sensor, lacked sufficient write-speed to the
memory card for it to be seriously considered by some professional
photographers.
From the late 1980s competition and technical innovations made 35 mm camera
systems more versatile and sophisticated by adding more advanced light metering
capabilities such as spot-metering; limited area metering such as used by Canon
with the F1 series; matrix metering as used by Nikon, exposure communication
with dedicated electronic flash units. The user interface also changed on many
cameras, replacing meter needle displays which were galvanometer-based and
thereby fragile, with light-emitting diodes (LEDs) and then with more
comprehensive liquid crystal displays (LCDs) both in the SLR viewfinder and
externally on the cameras' top plate using an LCD screen. Wheels and buttons
replaced the shutter dial on the camera and the aperture ring on the lens on
many models, although some photographers still prefer shutter dials and aperture
rings. Some manufacturers introduced image stabilization on certain lenses to
combat camera shake and to allow longer hand-held exposures without using a
tripod. This feature is especially useful with long telephoto lenses.
Digital SLRs (DSLRs)
Digital single-lens reflex camera
Canon, Nikon and Pentax have all developed digital SLR cameras using the same
lens mounts as on their respective film SLR cameras. Konica Minolta did the
same, but in 2006 sold their camera technology to Sony, who now build DSLRs
based on the Minolta lens mount. Samsung builds DSLRs based on the Pentax lens
mount. Olympus, on the other hand, chose to create a new digital-only Four
Thirds System SLR standard, adopted later by Panasonic and Leica.
Film formats
Early SLRs were built for large format photography, but this film format has
largely lost favor among professional photographers. SLR film-based cameras have
been produced for most film formats as well as for digital formats. These
film-based SLRs use the 35 mm format as, this film format offers a variety of
emulsions and film sensitivity speeds, usable image quality and a good market
cost. 35 mm film comes in a variety of exposure lengths: 20 exposure, 24
exposure and 36 exposure rolls. Medium format SLRs provide a higher-quality
image with a negative that can be retouched, unlike the 35 mm negative, when
this capability is required.
A small number of SLRs were built for APS such as the Canon IXUS and the Nikon
Pronea cameras. SLRs were also introduced for film formats as small as Kodak's
110, such as the Pentax Auto 110 which had interchangeable lenses.
The advent of digital photography in the late 1990s and the increasing
popularity and dominance of digital photography makes it very unlikely that
there will ever be any new film formats.
Common features
Other features found on many SLR cameras include through-the-lens (TTL) metering
and sophisticated flash control referred to as 'dedicated electronic flash'. In
a dedicated system, once the dedicated electronic flash is inserted into the
camera's hot shoe and turned on, there is then communication between camera and
flash. The camera's synchronization speed is set, along with the aperture. Many
camera models on the market today actually measure the light that reflects off
of the film plane, controls the flash duration of the electronic flash (some
flash units have a flash duration range of 1/1000 of a second to 1/50,000 of a
second), and then terminate exposure when the camera has received enough light
for the exposure.
Some electronic flash units can send out several short bursts of flash to
measure the distance, use the camera's inboard sensor(s) to determine the amount
of light that is reflected from the subject, then send out a main pulse of light
of just the right amount of light energy for a perfectly exposed photograph.
Sophisticated cameras can even make it easy for the photographer to balance
electronic flash and available light for an evenly balanced scene. While these
capabilities are hardly unique to the SLR, manufacturers included them early on
in the top models, whereas the best rangefinder cameras adopted such features
later.
Cut-away of a Minolta XG7 film-based SLR
Advantages
Many of the advantages of SLR cameras derive from viewing and focusing the image
through the attached lens. Most other types of cameras do not have this
function; subjects are seen through a viewfinder that is near the lens, making
the photographer's view different from that of the lens. SLR cameras provide
photographers with precision and confidence; they provide a viewing image that
will be exposed onto the negative exactly as it is seen through the lens. There
is no parallax error, and exact focus can be confirmed by eye — especially in
macro photography and when photographing using long telephoto lenses. The depth
of field may be seen by stopping down to the attached lens aperture, which is
only possible on most SLR cameras except for the least expensive models. Because
of the SLR's versatility, most manufacturers have a vast range of lenses and
accessories available for them.
Compared to most fixed-lens compact cameras, the most commonly used and
inexpensive SLR lenses offer a wider aperture range and larger maximum aperture
(typically f/1.4 to f/1.8 for a 50 mm lens). This allows photographs to be taken
in lower light conditions without flash, and allows a narrower depth of field,
which is useful for blurring the background behind the subject, making the
subject more prominent. 'Fast' lenses are commonly used in theater photography,
portrait photography, surveillance photography, and all other photography
requiring a large maximum aperture.
The variety of lenses also allows for the camera to be used and adapted in many
different situations. This provides the photographer with considerably more
control (i.e., how the image is viewed and framed) than would be the case with a
view camera. In addition, some SLR lenses are manufactured with extremely long
focal lengths, allowing a photographer to be a considerable distance away from
the subject and yet still expose a sharp, focused image. This is particularly
useful if the subject includes dangerous animals (e.g., wildlife); the subject
prefers anonymity to being photographed; or else, the photographer's presence is
unwanted (e.g., celebrity photography or surveillance photography). Practically
all SLR and DSLR camera bodies can also be attached to telescopes and
microscopes via an adapter tube to further enhance their imaging capabilities.
Disadvantages
In most cases, single-lens reflex cameras cannot be made as small or as light as
other camera designs — such as rangefinder cameras, autofocus compact cameras
and digital cameras with electronic viewfinders (EVF) — owing to the mirror box
and pentaprism/pentamirror. The mirror box also prevents lenses from having rear
elements closer to the film or sensor to be mounted unless the camera has a
mirror lockup feature; this means that simple designs for wide angle lenses
cannot be used. Instead, larger and more complex retrofocus designs are
required.
The SLR mirror 'blacks-out' the viewfinder image during the exposure. In
addition, the movement of the reflex mirror takes time, limiting the maximum
shooting speed. The mirror system can also cause noise and vibration.
Partially-reflective (pellicle) fixed mirrors avoid these problems and have been
used in a very few designs including the Canon Pellix, but these designs
introduce their own problems. These pellicle mirrors reduce the amount of light
travelling to the film plane or sensor and also can distort the light passing
through them, resulting in a less-sharp image. To avoid the noise and vibration,
many professional cameras offer a mirror lock-up feature, however, this feature
totally disables the SLR's focusing ability.
Currently, most digital SLRs cannot display a live preview on their rear LCD
displays, unlike digicams or bridge cameras, and must be held to the eye to view
and compose the image. This situation is changing with the arrival of the
Olympus E-330, Olympus E-410, Olympus E-510, Panasonic DMC-L1, Panasonic
DMC-L10, Leica Digilux 3, Canon EOS 40D, Canon EOS-1D Mark III, and Nikon D300
cameras.
Electronic viewfinders have the potential to give the 'viewing-experience' of a
DSLR (through-the-lens viewing) without many of the disadvantages, but as of
2006 sensor capability and display technology is insufficient for wide
acceptance among the advanced amateur or professional markets that purchase and
use digital SLRs. The SLRs and DSLRs will probably continue as the foremost
system because of the superiority in the use of the viewing and focusing optical
system.
Movie Modes
Movie modes are not available on current DSLRs, as the current focus has been to
optimize these cameras to provide the best possible quality and convenience in
taking 'still' images. This situation may change in the future with more
technological advancements.
Reliability of SLRs
In some cases of particular SLR models, there tends to be a higher rate of
breakdowns than a simpler camera of the same build quality. In contrast, more
expensive SLRs tend to be constructed with better materials to a much higher
standard than other camera types making their reliability better. Because many
SLRs have interchangeable lenses, there is a tendency for dust, sand and dirt to
get into the main body of the camera through the mirror box when the lens is
removed, thus dirtying or even jamming the mirror movement mechanism or the
shutter curtain mechanism itself. In addition, these particles can also jam or
otherwise hinder the focusing feature of a lens if they enter into the focusing
helicoid. The problem of sensor cleaning has been somewhat reduced in DSLRs as
some cameras have a built-in sensor cleaning unit.
Price and Affordability
The price of SLRs in general also tends to be somewhat higher than that of other
types of cameras, owing to the internal complexity. This is only aggravated by
the expense of additional components, such as a flash attachment or various
types of lenses. Typically the initial investment in equipment is prohibitive
enough to keep some casual photographers away from SLRs.
The Future of SLRs
For the foreseeable future, film-based SLRs may still be produced, as is still
the case with the 35 mm film-based Nikon F6, and some other 35 mm SLR models.
This may also be true with some medium-format film-based SLRs. It appears
inevitable that the Digital Single Lens Reflex camera design will eclipse film
SLR's design in convenience, sales and popularity. These cameras are currently
the marketing 'favorite' among advanced amateur and professional photographers.
Only those photographers who need a film-based SLR will continue to buy and use
such an instrument
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