Live preview is a feature that allows a digital camera's display screen to be used as a

viewfinder In photography, a viewfinder is what the photographer looks through to compose, and, in many cases, to focus the picture. Most viewfinders are separate, and suffer parallax, while the single-lens reflex camera lets the viewfinder use the main ...

. This provides a means of previewing framing and other exposure before taking the photograph. In most such cameras, the preview is generated by means of continuously and directly projecting the image formed by the

lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements ...

onto the main

image sensor An image sensor or imager is a sensor that detects and conveys information used to make an image. It does so by converting the variable attenuation of light waves (as they pass through or reflect off objects) into signals, small bursts of c ...

. This in turn feeds the electronic screen with the live preview image. The electronic screen can be either a liquid crystal display (LCD) or an electronic viewfinder (EVF).

Background

The concept for cameras with live preview largely derives from electronic (

video Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) syst ...

) TV cameras. Until 1995 most digital cameras did not have live preview, and it was more than ten years after this that the higher end digital single-lens reflex cameras (DSLR) adopted this feature, as it is fundamentally incompatible with the swinging-mirror

single-lens reflex A single-lens reflex camera (SLR) is a camera that typically uses a mirror and prism system (hence "reflex" from the mirror's reflection) that permits the photographer to view through the lens and see exactly what will be captured. With twin le ...

mechanism. The first digital still camera with an LCD for autogain framing live preview was the

Casio is a Japanese multinational electronics manufacturing corporation headquartered in Shibuya, Tokyo, Japan. Its products include calculators, mobile phones, digital cameras, electronic musical instruments, and analogue and digital watches. I ...

QV-10 in 1995. The first prosumer camera to use live view for both exposure simulation live preview ES-LV control and live preview framing was the fixed-lens

Canon PowerShot G1 The Canon PowerShot G is a series of digital cameras introduced by Canon in its PowerShot line in 2000. The G series cameras are Canon's flagship compact models aimed at photography enthusiasts desiring more flexibility than a point-and-shoot wit ...

from 2000 (possibly the first was Canon Powershot Pro70 in 1998), although this was still in the line of compact cameras. The first DSLR to use live view for framing preview only, like early other live view but non-mirrored digicams, was the fixed-lens

Olympus E-10 The Olympus E-10 is a digital single-lens reflex camera with a 4.0-megapixel CCD image sensor that was introduced in 2000. Unlike most digital SLRs the camera is not a system camera – its lens is fixed to the body. It has a TTL optical viewfin ...

from 2000. The first interchangeable-lens DSLR to use a live preview for framing was the Fujifilm FinePix S3 Pro, which was launched in October 2004. Its "Live Image" mode could display a live, black-and-white framing preview of the subject that could be magnified for manual focusing purposes, although the preview was limited to a duration of thirty seconds. The first interchangeable-lens DSLR following ES-LV capabilities of Canon's Powershot G1 (maybe, Canon Powershot Pro70) was in early 2005 with the

Canon EOS 20Da The Canon EOS 20D is an 8.2-megapixel semi-professional digital single-lens reflex camera, initially announced on 19 August 2004 at a recommended retail price of US$1,499. It is the successor of the EOS 10D, and was succeeded by the EOS 30D in ...

, a special version of the Canon EOS 20D with exposure simulation live view modifications for

astrophotography Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object (the Moon) was taken in 1840, but it was no ...

, which included a similar focus preview feature, plus first ever for any DSLR the new exposure simulation live view allowed capture of star exposures to selectable brightness 'effects' (Canon ExpSim LV). The first general-use interchangeable-lens DSLRs with live view for both exposure simulated live preview (ExpSim LV) and framing livepreview were the

Canon 20Da The Canon EOS 20D is an 8.2-megapixel semi-professional digital single-lens reflex camera, initially announced on 19 August 2004 at a recommended retail price of US$1,499. It is the successor of the EOS 10D, and was succeeded by the EOS 30D i ...

of 2005, followed by

Canon EOS 1Ds Mark III The EOS-1Ds Mark III is a digital SLR camera body by Canon designed for professional photographers. The Canon EOS 1Ds Mark III is successor to the EOS-1Ds Mark II and was announced in August 2007. The camera features a full-frame 21.1 megapix ...

and

Canon EOS 40D The Canon EOS 40D is a 10.1-megapixel semi-professional digital single-lens reflex camera. It was initially announced on 20 August 2007 and was released at the end of that month. It is the successor of the Canon EOS 30D, and is succeeded by the ...

of 2007. The first general-use interchangeable-lens DSLR with live view for framing preview only like most fixed lens digicams was the

Olympus E-330 The Olympus E-330 is a DSLR launched on 30 January 2006, using the Four Thirds System lens mount standard. Its main feature is its live image preview functionality, permitting an image to be previewed on the LCD screen. While live image previ ...

of 2006.

Types

There are two distinct modes of live-preview, with only a few manufacturers offering both in their digital cameras. The first is a more rudimentary type of live preview that displays the overall framing on an electronic display and allows a preview of what the camera's sensor will detect before the photograph is taken. This can be particularly helpful when the lighting conditions are too dark for an optical viewfinder. This type of live preview is the ''autogain/framing'' live view type (or ''framing priority display''). This requires traditional means of exposure determination requiring metering of the light coming through the lens, and interpreting the light intensity indication on an automatic

light meter A light meter is a device used to measure the amount of light. In photography, a light meter (more correctly an exposure meter) is used to determine the proper exposure (photography), exposure for a photograph. The meter will include either a Di ...

, and then adjusting exposure parameters for a desired effect. The second is a more sophisticated type of live preview that displays the exact exposure 'look' on an electronic display and allows the photographer to alter the exposure look via adjustments to parameters such as shutter speed, film speed or ISO, and

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An ...

, before the photograph is taken. This second type of live preview is the ''exposure simulation'' live preview type (or ''exposure priority display''). This type of live preview eliminates reliance on traditional light metering usage. Many modern bridge and compact cameras with movie mode have only an automatic exposure and limited

exposure compensation Exposure compensation is a technique for adjusting the exposure indicated by a photographic exposure meter, in consideration of factors that may cause the indicated exposure to result in a less-than-optimal image. Factors considered may include ...

control, and live view that is primarily for framing only.

Live-preview-only cameras

Live-preview-only cameras,that is cameras without an optical viewfinder, include four different categories: compact digital cameras,

bridge digital cameras A bridge is a structure built to span a physical obstacle (such as a body of water, valley, road, or rail) without blocking the way underneath. It is constructed for the purpose of providing passage over the obstacle, which is usually somethi ...

, and the newer

mirrorless interchangeable lens camera A mirrorless camera is a photo camera featuring a single, removable lens and a digital display. The camera does not have a reflex mirror or optical viewfinder like a digital single-lens reflex (DSLR) camera, but may have an electronic v ...

s and

Sony SLT camera Single-lens translucent (SLT) is a Sony proprietary designation for Sony Alpha cameras which employ a pellicle mirror, electronic viewfinder, and phase-detection autofocus system. They employ the same Minolta A-mount as Sony Alpha DSLR cameras. ...

s. Bridge cameras in general are higher-end, that is they contain more advanced features, better build quality, larger size, and are more expensive than compacts, but retain a small digital sensor. Mirrorless cameras feature a larger sensor and interchangeable lenses, like DSLRs, but sacrifice the SLR mirror mechanism and viewfinder to save size and cost, and hence only offer live preview. The SLT, developed by

Sony , commonly stylized as SONY, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan. As a major technology company, it operates as one of the world's largest manufacturers of consumer and professiona ...

, uses a mirror similar to that found in a DSLR. However, unlike the moving and fully reflective mirror of DSLRs, the SLT mirror is fixed and semi-reflective. New Zealand-based British photographer Gordon Laing describes the technology:

" fixed semi-reflective mirror allows around 70% of the light to pass through to the sensor for full-time live view composition, but reflects the remaining 30% or so to the phase change AF system, allowing quick and continuous autofocusing in Live View and movie modes. 30% is however too little for a traditional optical viewfinder, so Sony doesn't bother, instead using the main sensor to deliver a live image to an electronic viewfinder in addition to the main rear screen for composition."

The same technology was used by Olympus prior to Sony in the Olympus E-u.

Digital SLRs

Early examples of Exposure Simulation Live View (ES-LV) in advanced prosumer digicams with Full Manual / Manual ISO, such as Canon's PowerShot Pro70 (1998), Powershot G1 (2000) and Powershot Pro90 IS (2001), all feature an optical viewfinder or optical tunnel and display the preview image on their vari-angle swivel screen LCD. This gives a live real-time WYSIWYG (what you see is what you get) exposure simulation preview in Full Manual / Manual ISO mode, and Auto-Exposure (AE) / Manual ISO modes: P (Program), TV (Time Value: shutter speed priority), and Av (Aperture Value). If Auto ISO is used, Autogain (Auto-EV0) framing/focus live view suspends Exposure Simulation live view. This advanced exposure simulation live (pre-)view ES-LV on Canon's prosumer Powershots was absent on all interchangeable-lens DSLRs till Canon introduced a first ES-LV for an interchangeable-lens DSLR (they dubbed it: "ExpSim LV" version) in its EOS 20Da, to preview star exposures live, which was similar to ES-LV found in its advanced prosumer Powershot digicams. Later, Canon extended its more sophisticated DSLR ExpSim LV all shooting light conditions like its Powershot digicams. The most significant advances and difference in DSLR version of ES-LV was simulating exposure changes effects with chosen aperture changes without stopping down the aperture. The ES-LV of its Powershot digicams always kept its apertures stopped down, so no 'aperture exposure simulation' was needed, and briefly opened aperture to assess focus with shutter button partially depressed before a shot is taken. The ExpSim LV of its EOS lens DSLRs could achieve the same 'exposure simulation' effect in both aperture stop-down mode and aperture wide open of its EOS lenses, even if the aperture selection was narrower than widest diameter (wide open). In Autogain framing live view, such as in AE modes with Auto ISO in effect, using the dof button can take on two different effects: autogain during aperture stopped down (easy to see dof preview), and autogain-locked or suspended during aperture stopped down (difficult to see dof, just like looking with a non-live view DSLR of optical viewfinder (OVF) preview through-the-lens (TTL). For ES-LV digicam users and ExpSim LV DSLR users, this advanced method of "Adjustable/Selectable Live Previewable Exposure Evaluation/Determination" shooting in Full Manual / M ISO mode completely eliminated light meter sensor reading TTL common from the film era, making optimally desired exposure selection with live preview rear monitor screens virtually "instant at a glance", and time was saved doing any spot/area evaluative light metering TTL, which non-ES-LV and totally non-LV DSLR users doing the TTL "light meter reading" routine, same as their film SLR counterparts. The time saved assessing instant optimal exposure choices for any new or changing lit scenario, freed the ExpSim LV DSLR users to spend all their time shooting primarily with their optical viewfinder (OVF). When interchangeable-lens DSLRs with STILLS only ExpSim LV (APS-C EOS 20Da, APS-H EOS 1DMkIII, Full Frame (FF) EOS 1DsMkIII), with its ExpSim LV having Full Manual / M/Auto-ISO mode and AE / M/Auto-ISO mode, ExpSim LV was extended for the first time in any interchangeable-lens DSLR to Canon's FF ExpSim LV (1080p) video in 5DMkIII, it was only then, did use of OVF shifted over, more to the rear lcd monitor to shoot Cinematic (larger FF sensor frame than pro digital Super35mm and 35mm Cine cameras). D300liveview

The lesser Autogain Framing/Focus Live preview, borrowed from framing/focus autogain live view digicams, in lesser autogain live view DSLRs does not typically serve as their principal means of framing and previewing before taking a photograph, with this function still being mainly performed with optical viewfinder. The first interchangeable-lens DSLR to feature framing live preview was the 2004

Fujifilm , trading as Fujifilm, or simply Fuji, is a Japanese multinational conglomerate headquartered in Tokyo, Japan, operating in the realms of photography, optics, office and medical electronics, biotechnology, and chemicals. The offerings from the ...

FinePix S3 Pro. While initially largely a novelty feature, framing/focus only live-preview functionality from digicam framing/focus live view has become more common on DSLR cameras, and almost all new DSLRs have had the feature since mid-2008. This is particularly the case since the advent of movie mode common to digicam video features on these cameras. The following lists, for each brand and DSLR product line, the first camera to have live preview (product lines that did not exist when live preview came into use are not shown; as of August 2014, there is no product line in which live preview has been abandoned after being introduced): *

Canon Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the conceptual material accepted as official in a fictional universe by its fan base * Literary canon, an accepted body of works considered as high culture ** Western ca ...

: 20Da, 40D, 450D, 1000D, 1D Mark III, 5D Mark II, 7D *

: FinePix S3 Pro, FinePix IS Pro * Leica: Digilux 3 *

Nikon (, ; ), also known just as Nikon, is a Japanese multinational corporation headquartered in Tokyo, Japan, specializing in optics and imaging products. The companies held by Nikon form the Nikon Group. Nikon's products include cameras, camera ...

: D90, D300, D700, D3 * Olympus: E-10, E-330, E-30, E-3 *

Panasonic formerly between 1935 and 2008 and the first incarnation of between 2008 and 2022, is a major Japanese multinational conglomerate corporation, headquartered in Kadoma, Osaka. It was founded by Kōnosuke Matsushita in 1918 as a lightbulb ...

: DMC-L1 *

Pentax is a brand name used primarily by the Japanese multinational imaging and electronics company Ricoh for DSLR cameras, lenses, sport optics (including binoculars and rifle scopes), and CCTV optics. The Pentax brand is also used by Hoya Corporatio ...

: K20D, K-7, K-x *

Samsung The Samsung Group (or simply Samsung) ( ko, 삼성 ) is a South Korean multinational manufacturing conglomerate headquartered in Samsung Town, Seoul, South Korea. It comprises numerous affiliated businesses, most of them united under the ...

: GX-20 *

: A300, A350, A500, A55, and A77 The principal function of live preview on Canon DSLRs from the 20Da onwards has been to allow, via LCD viewing, rapid acquisition of consistent and predictable exposure selection before taking a photograph via its 'exposure simulation' (ExpSim) enabled mode, or exposure priority display. This mode replaces the shortcomings of traditional estimation involved in the through-the-lens (TTL) metering techniques of the older framing type live view DSLRs with autogain/framing only, DSLRs without live view, as well as the shortcomings of optical viewfinders when ambient lighting becomes too low. Real-time exposure simulation live preview (or exposure priority display) had been available in many prosumer cameras, such as the Canon PowerShot G series, before being available to in live view DSLRs. Some manufacturers of compact cameras, including prosumer models, still lack this exposure simulation live view feature, instead relying on the more rudimentary autogain/framing only live view, where slow focus and slow exposure estimation via TTL metering techniques are relied upon. Real-time exposure simulation capable live preview digital cameras make achieving the desired exposures, especially in manual modes, more quickly available for both still and video photography. Among the DSLRs that do manage to focus using the standard phase-detection sensors used by DSLRs, unlike some compact digital cameras none has managed to show 100% frame coverage. This removes one of the key advantages of live preview over optical viewfinders, especially on more budget cameras. Additionally, 100% coverage optical viewfinders have recently become more common and affordable with the appearance of the Canon EOS 7D, Nikon D300, Olympus E-3 and the Pentax K-7.Digital Camera and Photography: Tips, Information and News , Neocamera Blog » Blog Archive » Olympus E-3 - Another 100% Coverage Viewfinder
/ref> Still more recently, the (upper) mid-range Nikon D7000 has brought the feature to a somewhat lower price point. Some real-time exposure simulated capable live preview digital cameras also offer live histogram graphs for tonal balance or

color Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are assoc ...

, where the graph changes instantaneously as exposure adjustments are made. Other features include live depth of field (DOF) preview, and live indication of overexposed areas of the image Almost all modern bridge and compact cameras have a movie mode, while this feature only became available on DSLRs during 2008. The Nikon D90 with

720p 720p (1280×720 px; also called HD ready, standard HD or just HD) is a progressive HDTV signal format with 720 horizontal lines/1280 columns and an aspect ratio (AR) of 16:9, normally known as widescreen HDTV (1.78:1). All major HDTV broadcast ...

video was announced in August 2008, and the

Canon EOS 5D Mark II Canon or Canons may refer to: Arts and entertainment * Canon (fiction), the conceptual material accepted as official in a fictional universe by its fan base * Literary canon, an accepted body of works considered as high culture ** Western ca ...

with

1080p 1080p (1920×1080 progressively displayed pixels; also known as Full HD or FHD, and BT.709) is a set of HDTV high-definition video modes characterized by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the screen ve ...

video was announced in September 2008. The

was the first DSLR to offer full control over its real-time exposure simulation live preview for video, rather than just autogain/framing only live preview.

Advantages

Live preview can show additional information, such as an

image histogram An image histogram is a type of histogram that acts as a graphical representation of the tonal distribution in a digital image. It plots the number of pixels for each tonal value. By looking at the histogram for a specific image a viewer will ...

focal ratio In optics, the f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical Engineering'', 4th Ed., 2007 McGraw-Hill Pro ...

, camera settings, battery charge, and remaining storage space. Some implementations have a

focus peaking Focus peaking is a focusing aid in live preview or electronic viewfinder An electronic viewfinder (EVF) is a camera viewfinder where the image captured by the lens is displayed on a small screen (usually LCD or OLED) which the photographer c ...

feature that highlights areas of the frame that are in focus. They are also in several ways more accurate than an optical viewfinder (OVF): * Show the scene from the same viewpoint as the camera lens, without parallax. * Cope with high zoom-ratio lenses, without needing a bulky reflex mirror. * Show approximately how the scene will look under the chosen exposure, including white balance, saturation, effects etc. * Show a low-light scene brighter than it would appear with an OVF, just like the final image will look like. * Show 100% coverage of the final image. * Live view can also be used in video mode (which is not possible in an OVF)

Limitations

Live preview has the following limitations: * There may be a noticeable lag between the changes in the scene and the live view display. * Very few live preview implementations lack automatic gain control and become virtually blank in low-light conditions. * Live view of compact and bridge cameras with smaller sensors may be difficult to operate in darker environments and tends to lag severely. Live preview has been in use with

bridge camera Bridge cameras are cameras that fill the niche between relatively simple point-and-shoot cameras and interchangeable-lens cameras such as mirrorless cameras and single-lens reflex cameras (SLRs). They are often comparable in size and weight t ...

s for some years but with limited resolution and image quality. They are used in most mirrorless modern system cameras (e.g. Panasonic Micro Four Third System, Sony NEX, Sony SLT, Nikon V1). Many professional

photographer A photographer (the Greek φῶς (''phos''), meaning "light", and γραφή (''graphê''), meaning "drawing, writing", together meaning "drawing with light") is a person who makes photographs. Duties and types of photographers As in other ...

s and advanced amateurs prefer DSLR cameras that have a true optical through-the-lens viewfinder (OVF).

References

{{reflist Digital cameras