Digital cameras are made in a wide range of sizes, prices andcapabilities. Themajor ity are cameraphones, operatedas a mobileapplication throughthe cellphone menu. Professionalphotographers and many amateurs use larger,more expensivedigital single-lens reflex cameras (DSLR) for their greater versatility. Between these extremeslie digital compact cameras andbridge digital cameras that "bridge" thegap between amateur and professional cameras.Specialized cameras including multispectral imaging equipmentand astrographscontinue to serve the scientific, military, medical and other special purposes for whichdigital photographywas invented.

[edit]Compactdigital cameras

Subcompact with lensassembly retracted

Compact cameras are designed to be tiny andportable and are particularly suitable for casual and "snapshot" uses. Hence, they are also calledpoint-and-shoot cameras. The smallest, generally less than20 mm thick, are describedas subcompacts or "ultra-compacts" and some are nearly credit card size.[2]

Most, apart fromruggedized or water-resistantmodels, incorporate a retractable lensassembly allowing a thin camera to have a moderately long focal length and thus fullyexploit animage sensor larger than that on a camera phone,and a mechanized lenscap to cover the lens when retracted. The retracted andcapped lens is protected from keys,coins and other hard objects, thus makingit a thin, pocketable package. Subcompacts comm only haveone lugand a short wrist strap whichaids extraction from a pocket, while thicker compactsmay havetwo lugs forattaching a neck strap.

Compact cameras are usually designed to be easy to use, sacrificing advanced features and picture quality for compactness and simplicity;images can usuallyonly be stored using lossy compression (JPEG). Most have a built-inflash usually oflow power, sufficient for nearby subjects.Live preview is almostalways used to frame thephoto. Most have limitedmotion picturecapability. Compacts often have macrocapability andzoom lenses but thezoom range is usually less than forbridge and DSLR cameras. Generally a contrast-detect autofocus system, using theimage data from thelive preview feed of the mainimager,focuses the lens.

Typically, these cameras incorporate a nearly silentleaf shutter into their lenses.

Forlower cost and smaller size, these cameras typically useimage sensors with a diagonal of approximately 6mm, corresponding to a cropfactor around 6. This gives them weakerlow-light performance, greater depth offield, generallycloser focusing ability, and smaller components than cameras using larger sensors.

Starting in2011, some compactdigital cameras cantake 3D still photos. These3D compactstereo cameras cancapture3D panoramicphotos for play backon a3D TV.[3] Some of these arerugged and waterproof, and some haveGPS,compass, barometerand altimeter. [4]

[edit]Bridge cameras

Sony DSC-H2

Main article:Bridge camera

Bridge are higher-enddigital cameras that physically and ergonomically resemble DSLRs andshare with them some advanced features, butshare with compacts the use of a fixed lensand a small sensor. Like compacts, most uselive preview to frame theimage. Their autofocus uses the same contrast-detect mechanism, but manybridge cameras have amanual focus mode, in some cases using a separatefocus ring, for greater control. They originally "bridged" thegap between affordablepoint-and-shoot cameras andthe then unaffordable earlierdigital SLRs.

Due to the combination ofbig physical size but a small sensor, many of these cameras have very highly specified lenses with largezoom range and fastaperture, partially compensating for the inability tochange lenses.On some, the lens qualifiesas superzoom. To compensate for the lesser sensitivity of their small sensors, these cameras almostalways include animage stabilization system toenable longer handheld exposures.

These cameras are sometimes marketedas and confused withdigital SLR cameras since the appearance is similar.Bridge cameras lack the reflexviewing system of DSLRs, are usually fitted with fixed (non-interchangeable) lenses (although some have a lens thread toattachaccessory wide-angle or telephoto converters), and can usuallytake movies with sound. The scene is composedby viewing either the liquid crystal display or the electronicviewfinder (EVF). Most have a longer shutter lag than a true dSLR, but they arecapable of goodimage quality (with sufficientlight) whilebeing more compact andlighter than DSLRs. High-endmodels of this type have comparableresolutions tolow andmid-range DSLRs. Many of these cameras can storeimages in aRaw image format, or processed andJPEG compressed, or both. Themajor ity have a built-inflash similar to those found in DSLRs.

Inbright sun, the quality difference between a good compact cameraand a digital SLR is minimal butbridgecams aremore portable, cost less and have a similarzoom ability to dSLR. Thus aBridge cameramay better suit outdoor daytimeactivities, except when seeking professional-qualityphotos.[5]

Inlow light conditions and/orat ISO equivalents above 800, mostbridge cameras (or megazooms) lack inimage quality when compared to even entrylevel DSLRs. However, they do haveone major advantage: their much larger depth offield due to the small sensoras compared to a DSLR,allowing largerapertures with shorter exposure times.

A3D Photo Modewas introduced in2011, whereby the camera automaticallytakes a secondimage from a slightly different perspective and provides a standard .MPO file forstereo display. [6]

[edit]Mirrorless interchangeable-lens camera

Main article:Mirrorless interchangeable-lens camera

In late2008, a new type of camera emerged, combining the larger sensors and interchangeable lenses of DSLRs with thelive-preview viewing system of compact cameras, either through an electronicviewfinder oron the rearLCD. These are simpler andmore compact than DSLRs due to the removal of themirror box, and typically emulate the handling and ergonomics of either DSLRs or compacts. The system is usedby Micro Four Thirds, borrowing components from the Four Thirds DSLR system.

[edit]Digital single lens reflex cameras

Cutaway of anOlympus E-30 DSLR

Main article:Digital single-lens reflex camera

Digital single-lens reflex cameras (DSLRs) aredigital cameras basedon film single-lens reflex cameras (SLRs). Theytake theirname from their uniqueviewing system, in which amirror reflectslight from the lens through a separate opticalviewfinder.At themoment of exposure themirror flipsout of the way, making a distinctive "clack" soundand allowinglight to fall on theimager.

Since nolight reaches theimager during framing, autofocus is accomplished usingspecialized sensors in themirror box itself. Most 21stcentury DSLRs also have a "live view" mode that emulates thelive preview system of compact cameras, whenselected.

These cameras have much larger sensors than the other types, typically 18mm to 36mm on the diagonal (cropfactor 2, 1.6, or 1). This gives them superiorlow-light performance, less depth offield at a givenaperture,and a larger size.

Theymake use of interchangeable lenses; eachmajor DSLR manufacturer also sells aline of lenses specifically intended to be usedon their cameras. Thisallows theuser toselect a lens designed for theapplication at hand: wide-angle, telephoto,low-light,etc. So each lensdoes notrequire its own shutter, DSLRs use a focal-plane shutter in front of theimager, behind themirror.

[edit]Digital rangefinders

Main article: Rangefinder camera#Digital rangefinder

A rangefinder is auser-operated optical mechanism to measure subjectdistance once widely usedon film cameras. Mostdigital cameras measure subjectdistance automatically using electro-optical techniques, butit is not customary to say that they have a rangefinder.

[edit]Line-scan camera systems

Aline-scan camera is a camera device containing aline-scan image sensorchip,and a focusing mechanism. These cameras are almost solely used in industrial settings tocapture animage of a constantstream of moving material. Unlike video cameras,line-scan cameras use a single row ofpixel sensors, instead of a matrix of them. Data coming from theline-scan camerahas a frequency, where the camerascans aline, waits, and repeats. The data coming from theline-scan camera is comm only processedby a computer, to collect theone-dimensionalline data and to create atwo-dimensionalimage. The collectedtwo-dimensionalimage data is then processedby image-processing methods for industrial purposes.

Further information: Rotatingline camera

[edit]Integration

Many devices includedigital cameras built into or integrated into them. For example, mobilephones often includedigital cameras; those that do are knownas cameraphones. Other small electronic devices (especially those used for communication) suchas PDAs, laptops andBlackBerry devices often contain an integraldigital camera, and most 21stcentury camcorders can alsomake still pictures.

Due to the limited storagecapacity and general emphasison convenience rather thanimage quality, almostall these integrated or converged devices storeimages in the lossy but compactJPEG file format.

Mobilephones incorporatingdigital cameras were introduced inJapan in2001by J-Phone. In2003 cameraphones outsold stand-alone digital cameras, and in2006 theyoutsoldall film-based cameras anddigital cameras combined. These cameraphones reached a billion devices sold inonlyfive years, andby 2007more than half of the installedbase ofall mobilephones were cameraphones. Sales of separate cameras peaked in2008. [7]

Integrated cameras tend to beat the very lowest end of thescale ofdigital cameras in technical specifications, suchas resolution, optical quality,and ability to use accessories. With rapid development, however, thegap between mainstream compactdigital cameras and cameraphones is closing, and high-end cameraphones are competitive withlow-end stand-alone digital cameras of the same generation.

[edit]Waterproof

ACanon WP-1 waterproof 35mm film camera

Waterproofdigital cameras aredigital cameras that canmake pictures underwater. Waterproof housings have long been made but they cost almostas the cameras. Many waterproofdigital cameras are shockproof and resistant tolow temperatures;one of them isCanon PowerShot D10,one of the first underwaterdigital cameras.

These cameras become very popular during the holiday seas on, because many people want to save the bestmoments from their holidaysat the seaside. Waterproof watches and mobilephones were produced earlier. Mostmakers ofdigital cameras also produce waterproofones and every year they launchat leastone newmodel, for exampleSony,Olympus,Canon, Fuji.

HealthwaysMako Shark, an early waterproof camera,[8]was launched in 1958 and cost around 25 dollars.It was ahuge camera and pictures were black andwhite.

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