In photography, a viewfinder is a device on a

camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...

that a photographer uses to determine exactly where the camera is pointed, and approximately how much of that view will be photographed. A viewfinder can be mechanical (indicating only direction and approximate view), with simple optical components, with precision optics and optical functions, or a digital accessory device used with digital cameras.

View camera

These cameras had no separate viewfinder. The exact image (although upside-down and reversed left-right) was viewed on a

ground glass Ground glass is glass whose surface has been ground to produce a flat but rough ( matte) finish, in which the glass is in small sharp fragments. Ground glass surfaces have many applications, ranging from ornamentation on windows and table glass ...

installed either in a replaceable plateholder, or in a spring back where springs hold the ground glass at the focus plane until a photographic plateholder is slid in front of it. Spring backs usually had a flip-up cover protecting the ground glass. A black focusing cloth was used with larger models.

Mechanical finders

Later referred to as "sports finders", for many sports and newspaper applications optical viewfinders gave too small an image and were inconvenient to use for scenes that were changing rapidly. For these purposes a simple arrangement of two wire rectangles, a smaller one nearer the eye and a larger one further away, was used, without optics; the two rectangles were aligned so the smaller one was centered in the larger, and the larger rectangle would give an indication of what would be included. Cameras with sportsfinders usually had optical viewfinders also.

Simple optical viewfinders

A single divergent (plano-concave) lens, in front of a frame, when close to the eye, acts as a viewfinder. Adding a convergent (plano-convex) lens makes a very short reversed Galilean (upright image)

telescope A telescope is a device used to observe distant objects by their emission, Absorption (electromagnetic radiation), absorption, or Reflection (physics), reflection of electromagnetic radiation. Originally, it was an optical instrument using len ...

. For movie camera or others with changeable lenses, outline marks on one of the viewfinder lenses could show the different fields of view for the different camera lenses.

Waist level (reflecting) viewfinders

Simple reflecting viewfinders, known also as "brilliant finders", comprised a small forward-looking lens, a small mirror at 45° behind it, and a lens at the top; the user held the camera at waist level and looked down into the lens, where a small image could be seen. Such viewfinders were integrated into

box camera A box camera is a simple type of camera, the most common form being a cardboard or plastic box with a lens in one end and film at the other. They were sold in large numbers during the late 19th and early 20th centuries. The lenses are often single ...

s, and fitted to the side of

folding camera A folding camera is a camera type. Folding cameras fold into a compact and rugged package for storage. The lens and shutter are attached to a lens-board which is connected to the body of the camera by a light-tight folding bellows. When the c ...

s. These viewfinders were fitted to inexpensive cameras. File:Ansco Panda.jpg, Child's waist-view box camera File:Mamiya 645 1000s waist level finder.JPG, Mamiya 645 1000s waist level finder File:Robot Royal III camera with Zeiss Ikon waist level viewfinder attachment.jpg, Robot Royal III camera with Zeiss Ikon waist level viewfinder attachment

Twin-lens reflex viewfinders

Twin-lens reflex A twin-lens reflex camera (TLR) is a type of camera with two objective lenses of the same focal length. One of the lenses is the photographic objective or "taking lens" (the lens that takes the picture), while the other is used for the viewfinde ...

(TLR) cameras use a viewfinding lens with the same

focal length The focal length of an Optics, optical system is a measure of how strongly the system converges or diverges light; it is the Multiplicative inverse, inverse of the system's optical power. A positive focal length indicates that a system Converge ...

as the camera lens, so it has the same field of view and

focus Focus (: foci or focuses) may refer to: Arts * Focus or Focus Festival, former name of the Adelaide Fringe arts festival in East Australia Film *Focus (2001 film), ''Focus'' (2001 film), a 2001 film based on the Arthur Miller novel *Focus (2015 ...

properties. With a mirror, of similar size to the film, held at 45°, it projects an upright image onto a focusing ground glass screen viewable from above. The camera can be then be held steady at waist level. Although the viewfinder lens was similar to the camera lens, the optical quality was less important and so the cost is reduced. TLR viewfinders do not have the interrupted viewing and

shutter lag In photography, shutter lag is the delay between triggering the shutter and when the photograph is actually recorded, which includes all lag between when the shutter button is pressed and when the photo is taken, including metering and focus lag. ...

of the SLR type and so is preferred for dance photography. Reinhold Heidecke cited his experience with

periscope A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer's current position. In its simplest form, it consists of an outer case with ...

focusing from the German trenches in 1916 as the inspiration for the

Rolleiflex Rolleiflex is a long-running and diverse line of high-end cameras originally made by the German company Franke & Heidecke, and later Rollei-Werke. History The "Rolleiflex" name is most commonly used to refer to Rollei's premier line of med ...

line in 1929. Some similar-looking cameras are actually simple box cameras with a waist-level viewfinder.

Single-lens reflex viewfinders

Single-lens reflex In photography, a single-lens reflex camera (SLR) is a type of camera that uses a mirror and prism system to allow photographers to view through the lens and see exactly what will be captured. SLRs became the dominant design for professional a ...

(SLR) cameras use the camera lens itself, to completely eliminate

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...

, the significant field-of-view error for close subjects caused by the offset distance between the viewfinder's lens and the camera's lens. Early SLRs were

plate camera A camera is an instrument used to capture and store images and videos, either digitally via an electronic image sensor, or chemically via a light-sensitive material such as photographic film. As a pivotal technology in the fields of photograp ...

s, with a mechanism to insert a mirror between the lens and the film which reflected the light upwards, where it could be seen at waist level on a ground glass screen. When ready to take the picture, the mirror was pivoted out of the way (without moving the camera). Later SLR still cameras had a mechanism which flipped the mirror out of the way when the shutter button was pressed, opened and closed the shutter, and then moved the mirror back. The Zeiss Ikon Contax S was the first SLR camera to allow easy eye-level viewing by using a roof

pentaprism A pentaprism is a five-sided reflecting prism (optics), prism used to deviate a beam of light by a constant 90°, even if the entry beam is not at 90° to the prism. The beam reflects inside the prism ''twice'', allowing the transmission of an i ...

to laterally reverse the inverted camera image (the reflex mirror had already vertically reversed the image). SLR movie cameras used a

beamsplitter A beam splitter or beamsplitter is an optical device that splits a beam of light into a transmitted and a reflected beam. It is a crucial part of many optical experimental and measurement systems, such as interferometers, also finding widespr ...

partial mirror to split the camera image between the shutter and film, and the viewfinder. A major advantage of SLR viewfinders is that any change of camera lens did not affect the viewing accuracy, and accurate camera focus did not depend on correct linking or calibration.

Rangefinders

Some sophisticated 20th century cameras with direct viewfinders had coincidence (split-image) rangefinders, initially with separate windows from the viewfinder, later integrated with it; they were called

rangefinder camera A rangefinder camera is a camera fitted with a rangefinder, typically a split-image rangefinder: a range-finding focusing mechanism allowing the photographer to measure the subject distance and take photographs that are in sharp focus. Most v ...

s. Cameras with interchangeable lenses had to indicate the field of view of each lens in the viewfinder; more usually, interchangeable viewfinders to match the lenses were used. File:LEI0440 Leica IIIf chrom - Sn. 580566 1951-52-M39 Blitzsynchron front view-6531 hf-.jpg, Leica IIIf viewfinder camera, 1951 File:Two TEWE 35-200MM ZOOM FINDER.jpg, German Tewe 35 mm to 200 mm zoom viewfinder File:Concord 4060AF.JPG, Early 21st century digicam with viewfinder

Contemporary viewfinders

Viewfinders can be

optical Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

electronic Electronic may refer to: *Electronics, the science of how to control electric energy in semiconductors * ''Electronics'' (magazine), a defunct American trade journal *Electronic storage, the storage of data using an electronic device *Electronic c ...

. An optical viewfinder is simply a reversed

that displays what the camera sees. It has many drawbacks, but it also has advantages; it consumes no power, it does not wash out in sunlight, and it has "full resolution" (i.e. the resolution of the photographer's

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

). Modern electronic viewfinders (EVF) are

LCD A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers to display information. Liquid crystals do not em ...

OLED An organic light-emitting diode (OLED), also known as organic electroluminescent (organic EL) diode, is a type of light-emitting diode (LED) in which the emissive electroluminescent layer is an organic compound film that emits light in respon ...

based display devices. In addition to its primary purpose, an electronic viewfinder can be used to replay previously captured material, and as an

on-screen display An on-screen display (OSD) is an image superimposed on a screen picture, commonly used by modern television sets, VCRs, and DVD players to display information such as volume, channel, and time. History In the past, most adjustments on TV set ...

to browse through menus. A still camera's optical viewfinder typically has one or more small supplementary

LED A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresp ...

displays surrounding the view of the scene. On a film camera, these displays show shooting information such as the

shutter speed In photography, shutter speed or exposure time is the length of time that the film or digital sensor inside the camera is exposed to light (that is, when the camera's shutter (photography), shutter is open) when taking a photograph. The am ...

and

aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...

and, for

autofocus An autofocus (AF) optical system uses a sensor, a control system and a motor to focus on an automatically or manually selected point or area. An electronic rangefinder has a display instead of the motor; the adjustment of the optical system h ...

cameras, provide an indication that the image is correctly focussed. Digital still cameras will typically also display information such as the current

ISO The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Me ...

setting and the number of remaining shots which can be taken in a burst. Another display which overlays the view of the scene is often provided. It typically shows the location and state of the camera's provided auto-focus points. This overlay can also provide lines or a grid which assist in picture

composition Composition or Compositions may refer to: Arts and literature *Composition (dance), practice and teaching of choreography * Composition (language), in literature and rhetoric, producing a work in spoken tradition and written discourse, to include ...

. It is not uncommon for a camera to have two viewfinders. For example, a digital still camera may have an optical viewfinder and an electronic one. The latter can be used to replay previously captured material, has an

, and can be switched off to save power. A

camcorder A camcorder is a self-contained portable electronic device with video and recording as its primary function. It is typically equipped with an articulating screen mounted on the left side, a belt to facilitate holding on the right side, hot-sw ...

may have two viewfinders, both electronic. The first is viewed through a magnifying eyepiece, and due to a rubber eyepiece it can be viewed perfectly even in bright light. The second viewfinder would be larger, of a higher resolution, and may be mounted on the side of the camera. Because it consumes more power, a method is often provided to turn it off to save energy. In late 2010, Fujifilm announced hybrid viewfinder of optical viewfinder and electronic viewfinder in one viewfinder for its highend compact cameras. There is a half mirror prism that reflect data from LCD to the optical viewfinder, so we can see both the shooting frame and the shooting data. A button can change the hybrid function to electronical viewfinder by blocking the image through the optical viewfinder with moving a half mirror prism to be a straight up mirror. Viewfinders are used for virtually all cameras whether still or movie, film, electronic analog (Television) or digital. Many digital sensor cameras do not have a separate viewfinder. For those cameras, the electronic image is shown on a small accessory screen for composition and focusing purposes.

CCTV Closed-circuit television (CCTV), also known as video surveillance, is the use of closed-circuit television cameras to transmit a signal to a specific place on a limited set of monitors. It differs from broadcast television in that the signa ...

s and

webcam A webcam is a video camera which is designed to record or stream to a computer or computer network. They are primarily used in Videotelephony, video telephony, live streaming and social media, and Closed-circuit television, security. Webcams can b ...

s do not need any viewfinding device.

References

{{Reflist Photography equipment Camera features Optical devices