Digital photography

Digital photography

Digital photography is a form of photography that utilizes digital technology to make digital images of subjects. Until the advent of digital technology, photography used photographic film to create images which could be made visible by photographic processing. Digital images can be displayed, printed, stored, manipulated, transmitted, and archived using digital and computer techniques, without chemical processing.
Digital photography is one of several forms of digital imaging. Digital images are also created by non-photographic equipment such as computer tomography scanners and radio telescopes. Digital images can also be made by scanning conventional photographic images.

Sensors and storage

Sensors read the intensity of light as filtered through different color filters, and digital memory devices store the digital image information, either as RGB color space or as raw data.
There are two main types of sensors:
charge-coupled device (CCD) – photocharge is shifted to a central charge-to-voltage converter
CMOS sensors ("Active pixel sensor")
Nearly all digital cameras now use built in and/or removable solid state flash memory. Digital camcorders that double as a digital still camera use flash memory, discs and internal hard disks. For a time floppy disks and mini-CDs were used in early digital cameras such as the Sony Mavica range.

Multifunctionality and connectivity

Except for some linear array type of cameras at the highest-end and simple web cams at the lowest-end, a digital memory device (usually flash memory; floppy disks and CD-RWs are less common) is usually used for storing images, which may then be transferred to a computer later.
Digital cameras can take pictures, and may also record sound and video. Some can be used as webcams, some can use the PictBridge standard to connect to a printer without using a computer, and some can display pictures directly on a television set. Similarly, many camcorders can take still photographs, and store them on videotape or on flash memorycards.

Performance metrics

The quality of a digital image is the sum of various factors, many of which are similar to film cameras. Pixel count (typically listed in megapixels, millions of pixels) is only one of the major factors, though it is the most heavily marketed. Pixel count metrics were created by the marketing organizations of digital camera manufacturers because consumers can use it to easily compare camera capabilities. It is not, however, the major factor in evaluating a digital camera. The processing system inside the camera that turns the raw data into a color-balanced and pleasing photograph is the most critical, which is why some 4+ megapixel cameras perform better than higher-end cameras.
Lens quality: resolution, distortion, dispersion (see Lens (optics))
Capture medium: CMOS, CCD, Negative film, Reversal Film etc.
Capture format: pixel count, digital file type (RAW, TIFF, JPEG), film format (135 film, 120 film, 5x4, 10x8).
Processing: digital and / or chemical processing of 'negative' and 'print'.

Pixel counts

The number of pixels n for a given maximum resolution (w horizontal pixels by h vertical pixels) is the product n = w × h. This yields e. g. 1.92 megapixels (1,920,000 pixels) for an image of 1600 × 1200. The majority of compact (not SLR) digital cameras have a 4:3 aspect ratio, i.e. w/h = 4/3. [1]. According to Digital Photography Review, the 4:3 ratio is because "computer monitors are 4:3 ratio, old CCD's always had a 4:3 ratio, and thus digital cameras inherited this aspect ratio."[1]
The pixel count quoted by manufacturers can be misleading as it may not be the number of full-colour pixels. For cameras using single-chip image sensors the number claimed is the total number of single-colour-sensitive photosensors, whether they have different locations in the plane, as with the Bayer sensor, or in stacks of three co-located photosensors as in the Foveon X3 sensor. However, the images will have different numbers of RGB pixels: the Bayer-sensor cameras produce as many RGB pixels as photosensors via demosaicing (interpolation), while the cameras with Foveon sensors produce uninterpolated image files with one-third as many RGB pixels as photosensors. It is difficult to compare the resolutions based on the megapixel ratings of these two types of sensors, and therefore sometimes subject of dispute.

Resolution

Resolution provides an indication of the amount of detail that is captured, but, like the other metrics, resolution is just another factor out of many in determining the quality of an image. Furthermore, different methods of creating an image make it impossible to compare the resolutions of cameras simply based on the number of pixels produced by the image sensor. For example, the Sigma SD14 camera uses Foveon technology, which is quite different from most other digital cameras. It claims to be a 14 megapixel camera, but is generally considered to have detail-capturing capabilities roughly equivalent to 9 megapixels in terms of Bayer sensors. [2]
The relative increase in detail resulting from an increase in resolution is better compared by looking at the number of pixels across (or down) the picture, rather than the total number of pixels in the picture area. For example, a sensor of 2560 × 1600 sensor elements is described as "4 megapixels" (2560 × 1600 = 4,096,000). Increasing to 3200 × 2048 increases the pixels in the picture to 6,553,600 (6.5 megapixels), a factor of 1.6, but the pixels per cm in the picture (at the same image size) increases by only 1.25 times. A measure of the comparative increase in linear resolution is the square root of the increase in area resolution, i.e., megapixels in the entire image.
Resolution in pixels is not the only measure of image quality; a larger sensor with the same number of pixels will generally produce a better image than a smaller one. One of the most important differences is an improvement in image noise. This is one of the advantages of digital SLR cameras, which have larger sensors than simpler cameras of the same resolution.

Dynamic range

Practical imaging systems, digital and film, have a limited dynamic range which can be reproduced accurately. Highlights of the subject which are too bright will be rendered as white, with no detail; shadows which are too dark will be rendered as black. The loss of detail is not abrupt with film, or in dark shadows with digital sensors: some detail is retained as brightness moves out of the dynamic range. "Highlight burn-out" of digital sensors, however, can be abrupt, and highlight detail may be lost. And as the sensor elements for different colors saturate in turn, there can be gross hue or saturation shift in burnt-out highlights.
Some digital cameras can show these blown highlights in the image review, allowing the photographer to re-shoot the picture with a modified exposure. Others compensate for the total contrast of a scene by selectively exposing darker pixels longer. A third technique is used by Fujifilm in its FinePix S3 Pro digital SLR. The image sensor contains additional photodiodes of lower sensitivity than the main ones; these retain detail in parts of the image too bright for the main sensor.
High dynamic range imaging (HDR) addresses this issue by increasing the dynamic range of images by either
increasing the dynamic range of the image sensor or
by using exposure bracketing and post-processing the separate images to create a single image with a higher dynamic range.
HDR images curtail burn-outs and black-outs.

Movie Camera

Movie camera

From Wikipedia, the free encyclopedia
Jump to: navigation, searchThe Arricam ST, a popular 35 mm film camera currently used on major productions.
This article is about motion picture film cameras. See video camera for cameras which record images electronically. The movie camera is a type of photographic camera which takes a rapid sequence of photographs on strips of film. In contrast to a still camera, which captures a single snapshot at a time, the movie camera takes a series of images, each called a "frame". This is accomplished through an intermittent mechanism. The frames are later played back in a movie projector at a specific speed, called the "frame rate" (number of frames per second). While viewing, a person's eyes and brain merge the separate pictures together to create the illusion of motion.[1]

Technical details

Most of the optical and mechanical elements of a movie camera are present in the movie projector. The requirements for film tensioning, take-up, intermittent motion, loops, and rack positioning are almost identical. The camera will not have an illumination source and will maintain its film stock in a light-tight enclosure. A camera will also have exposure control via an iris aperture located on the lens. Also, there is a rotating, sometimes mirrored shutter behind the lens, which alternately passes the light from the lens to the film, or reflects it into the viewfinder. The righthand side of the camera is often referred to by camera assistants as "the dumb side" because it usually lacks indicators or readouts and access to the film threading, as well as lens markings on many lens models. More recent equipment often has done much to minimize these shortcomings, although access to the film movement block by both sides is precluded by basic motor and electronic design necessities.The standardized frame rate for commercial sound film is 24 frames per second. The standard commercial (i.e., movie-theater film) width is 35 millimeters, while many other film formats exist. The standard aspect ratios are 1.66, 1.85, and 2.39 (anamorphic). NTSC video (common in North America and Japan) plays at 29.97 frames/s; PAL (common in most other countries) plays at 25 frames/s. These two television and video systems also have different resolutions and color encodings. Many of the technical difficulties involving film and video concern translation between the different formats. Video aspect ratios are 4:3 for full screen and 16:9 for widescreen.

Multiple cameras

Multiple synchronized cameras may be used and the films then projected simultaneously, either on a single three-image screen (Cinerama) or upon multiple screens forming a complete circle, with gaps between screens through which the projectors illuminate an opposite screen. (See Circle-Vision 360°.)
Sound synchronization

One of continuing problems in film is synchronizing a sound recording with the film. Most film cameras do not record sound internally; instead, the sound is captured separately by a precision audio device. This is called double-system. The exceptions to this are the single-system news film cameras, which had either an optical --or later-- magnetic recording head inside the camera. For optical recording, the film only had a single perforation and the area where the other set of perforations would have been was exposed to a controlled bright light that would burn a waveform image that would later regulate the passage of light and playback the sound. For magnetic recording, that same area of the single perf 16 mm film that was prestriped with a magnetic stripe. A smaller balance stripe existed between the perforations and the edge to compensate the thickness of the recording stripe to keep the film wound evenly.
The clapper board which typically starts a take is used as a reference point for the editor to sync the picture to the sound (provided the scene and take are also called out so that the editor knows which picture take goes with any given sound take). It also permits scene and take numbers and other essential information to be seen on the film itself. Aaton cameras have a system called AatonCode that can "jam sync" with a timecode-based audio recorder and prints a digital timecode directly on the edge of the film itself. However, the most commonly used system at the moment is unique identifier numbers exposed on the edge of the film by the film stock manufacturer (KeyKode is the name for Kodak's system). These are then logged (usually by a computer editing system, but sometimes by hand) and recorded along with audio timecode during editing. In the case of no better alternative, a handclap can work if done clearly and properly, but often a quick tap on the microphone (provided it is in frame for this gesture) is preferred.
Some cameras have low-accuracy ("non-sync" or MOS) film-advance systems. One of the most common uses of these cameras in commercial films are the spring-wound cameras used in hazardous special effects, known as "crash cams". Scenes shot with these have to be kept short, or resynchronized manually with the sound. MOS cameras are also often used for second-unit work or anything involving variable or non-standard speed filming. Due to their non-sync nature, some designs forgo traditional low-noise considerations for a studio camera and thus are quite noisy.
The most popular 35 mm cameras in use today are Arriflex, Moviecam (now owned by the Arri Group), and Panavision models. For very high speed filming, PhotoSonics are used.

Home movie cameras

Movie cameras, although available before the Second World War, had an upsurge in popularity in the immediate post-war period giving rise to the creation of home movies. Compared to the pre-war models, these cameras were small, light, fairly sophisticated and affordable. While a basic model might have a single fixed aperture/focus lens, a better version might have three or four lenses of differing apertures and focal lengths on a rotating turret. A good quality camera might come with a variety of interchangeable, focusable lenses or possibly a single zoom lens. The viewfinder was normally a parallel sight within or on top of the camera body. In the 1950s and for much of the 1960s these cameras were powered by clockwork motors, again with variations of quality. A simple mechanism might only power the camera for some 30 seconds, while a geared drive camera might work for as long as 75 - 90 seconds (at standard speeds). Even today there is a market among collectors for these types of camera, as the engineering and materials were of a very high standard and no battery is required. While film stock and the ability to process it exists, these cameras can still be used.
The common film used for these cameras was termed Standard 8, which was a strip of 16 millimetre wide film which was only exposed down one half during shooting. The film had twice the number of perforations as film for 16mm cameras and so the frames were half as high and half as wide as 16mm frames. The film was removed and placed back in the camera to expose the frames on the other side once the first half had been exposed. Once the film was developed it was spliced down the middle and the ends attached, giving 50 foot of Standard 8 film from a spool of 25 foot of 16 mm film. 16 mm cameras, mechanically similar to the smaller format models, were also used in home movie making but were more usually the tools of semi professional film and news film makers.
In the 1960s a new film format, Super8, coincided with the advent of battery operated electric movie cameras. The new film, with a larger frame print on the same width of film stock, came in a cassette which simplified changeover and developing. Another advantage of the new system is that they had the capacity to record sound, albeit of indifferent quality. Camera bodies, and sometimes lenses, were increasingly made in plastic rather than the metals of the earlier types. As the costs of mass production came down, so did the price and these cameras became very popular. This type of format and camera was more quickly superseded for amateurs by the advent of video cameras, although some professionals continued to make use of its visual characteristics alongside larger format film and video cameras.

Digital Camera Pictures

DIGITAL CAMERA PICTURES

Video Cameras

Video Cameras & Filming

This lesson will present a few basics for using a video camera to record a scene for inclusion in a multimedia presentation.
We will be using a Panasonic camcorder (analog) and a Sony Handicam (digital) . Take the time to become familiar with their basic operation before you begin shooting.

Basic Steps:

Following a few simple rules when filming for desktop video will improve the quality of the shot:
Keep the background simple to focus attention on the subject.
Make sure that your lighting is adequate. More light will help you keep the subject in focus and make colors look better too.
Avoid large differences in brightness between background and subject to prevent washing out detail in the subject. If the background is brighter than the subject and the camera angle can't be changed, a backlight setting may help.
Use a tripod. A steady image is essential for better compression and for a more professional look.
Double check the sound level. It is often better to avoid using an internal microphone because camera vibrations generate a lot of noise. If you need to use in internal microphone, test it first and compare the quality to the sound from an external microphone to be sure you are satified. However, external microphones can sometimes pick of radio interference. Get the microphone as close as possible to the subject. Shoot in a quiet environment, and monitor the sound during filming if possible.
The smaller the image size of the final product, the closer you should zoom in on the subject to create a close-up shot for your video frame.
Keep it short and keep up the pace. Beginners tend to make shots too long. Long videos with little content take up space and time and slow down the rhythm without adding much to the overall quality of the presentation.
Remember to check the focus.
If you use auto-focus, test it to make sure it works well. On some cameras, auto-focus can cause sudden unintentional changes in focus when something moves in your frame.
Avoid changing the zoom, panning, or tracking while shooting for desktop video.
On some cameras it may be necessary to set white balance, check for indoor/outdoor settings, turn off any date stamp. When all else fails, read the manual.

Be sure that your subject is centered and well lit. A good shooting environment will yield a better result.
Video creates large files, so avoid occupying screen area with unnecessary background. Stable backgrounds compress better than moving backgrounds, so try to avoid any camera motion. Moving the camera or changing the frame in any way (zooming in or out) makes file compression more difficult because it generates a greater difference between video frames.
Sound is actually harder to do well than images, so don't underestimate the attention that you need to devote to getting a good sound track. The environment is full of sounds. Human hearing is all about filtering out the things that are not important and paying attention only to the important details of what we hear. In a recording, we can hear all of the noises that we normally do not notice because our perception filters them out. Make sure that the sound track includes only the sounds that you want.
The larger the screen, the easier it is to see facial features and the more screen area may be occupied by background. Cinema, television, and computer screen video formats must take relative size into consideration when determining the best framing for the subject. Which of the following frames is a better choice for digital video?

Other Video Capture products

In our previous lesson on video capture, we looked at using Adobe Premiere to capture a video.
There are numerous tools that allow us to capture video. Some video cards have a built-in video capture function, there are video capture devices that connect to a computer through a USB or Firewire connector, one might have a separate card that only does video capture, or a digital video camera might transfer the digital video as a file directly to your computer.
The photo at the right shows the interface for capturing video using the Matrox Marvel G400 video card. This card is designed to capture video in MPG format, so that is the CODEC (compression / decompression algorithm) that we would use with this device. Once the video is captured, we use video editing software to make any changes needed. Because there are so many different tools on the market, and because they behave so differently, it is necessary to follow the directions that come with the software and hardware that you have purchased.

Web camera

Webcam

Webcams (web cameras) are small cameras, (usually, though not always, video cameras) whose images can be accessed using the World Wide Web, instant messaging, or a PC video conferencing application. The term webcam is also used to describe the low-resolution digital video cameras designed for such purposes, but which can also be used to record in a non-real-time fashion.
Web-accessible cameras involve a digital camera which uploads images to a web server, either continuously or at regular intervals. This may be achieved by a camera attached to a PC, or by dedicated hardware. Videoconferencing cameras typically take the form of a small camera connected directly to a PC. Analog cameras are also sometimes used (often of the sort used for closed-circuit television), connected to a video capture card and then directly or indirectly to the internet.
History
Started in 1991, the first webcam was pointed at the Trojan room coffee pot in the computer science department of Cambridge University. This webcam is now defunct, as it was finally switched off on August 22, 2001. The final image captured by the camera can still be viewed at the webcam's homepage [1].
The oldest webcam still operating is FogCam at San Francisco State University, which has been running continuously since 1994[1].
As with many new technologies, webcams and webcam chat found early commercial adoption and aggressive technology advancement through use by the pornography industry.[citation needed] The adult industry required 'live' images and requested a Dutch developer to write a piece of software that could do this without requiring web browser plugins.[citation needed] This led to the birth of the 'live streaming webcam', which is still available in various forms today.[citation needed]
One of the most widely reported-on webcam sites was JenniCam, started in 1996, which allowed Internet users to constantly observe the life of its namesake, somewhat like reality TV series Big Brother, launched three years later[2]. More recently, the website Justin.tv has shown a continuous video and audio stream from a mobile camera mounted on the head of the site's star.

Web-accessible cameras

In addition to use for personal videoconferencing, it was quickly realised that World Wide Web users enjoyed viewing images from cameras set up by others elsewhere in the world. While the term "webcam" refers to the technology generally, the first part of the term ("web-") is often replaced with a word describing what can be viewed with the camera, such as a netcam or streetcam. Educators can use webcams to take their students on virtual field trips.
Today there are millions of webcams that provide views into homes, offices and other buildings as well as providing panoramic views of cities (Metrocams) and the countryside. Webcams are used to monitor traffic with TraffiCams, the weather with WeatherCams and even volcanoes with VolcanoCams. Webcam aggregators allow viewers to search for specific webcams based on geography or other criteria.
Software
Webcams connected to PCs can act as web-accessible cameras with certain software. The software uploads pictures to an internet server (via FTP or HTTP), from which they can be made accessible to anyone over the web.
Usually, this kind of software works with almost every webcam. Webcam software can be configured in many ways and will often include options for image size and quality, overlaying logos, and time stamping images. Many different programs are available, some of them are free and open source

Videoconferencing

As webcam capabilities have been added to instant messaging text chat services such as AOL Instant Messenger, one-to-one live video communication over the internet has now reached millions of mainstream PC users worldwide. Increased video quality has helped webcams encroach on traditional video conferencing systems. New features such as lighting, real-time enhancements (retouching, wrinkle smoothing and vertical stretch) can make users more comfortable, further increasing popularity. Features and performance vary between programs.
Videoconferencing support is included in programs including Yahoo Messenger, AOL Instant Messenger (AIM), Windows Live Messenger, Skype, iChat, Ekiga and Camfrog.
Some online video broadcasting sites have taken advantage of this technology to create internet television programs centered around two (or more) people "diavlogging" with each other from two different places. Among others, BloggingHeads.tv uses this technology to set up conversations between prominent journalists, scientists, bloggers, and philosophers.

Video security
Webcams are being used for security purposes. Software is available allowing PC-connected cameras to watch for movement and sound, recording both when they are detected; these recordings can be saved to the computer, e-mailed or uploaded to the internet. In one well-publicised case [3] a computer e-mailed out images as the burglar stole it, allowing the owner to give police a clear picture of the burglar's face even after the computer had been stolen.

As a control input device

Special software can use the video stream from a webcam to assist or enhance a user's control of applications and games. Video features, including faces, shapes, models and colors can be observed and tracked to produce a corresponding form of control. For example, the position of a single light source can be tracked and used to emulate a mouse pointer, a head mounted light would allow hands-free computing and would greatly improve computer accessibility. This can also be applied to games, providing additional control, improved interactivity and immersiveness.
FreeTrack is a free webcam motion tracking application for Microsoft Windows that can track a special head mounted model in up to six degrees of freedom and output data to mouse, keyboard, joystick and FreeTrack supported games.
The EyeToy for the PlayStation 2 and similarly the Xbox Live Vision Camera for the Xbox 360 and Xbox Live are color digital cameras that have been used as control input devices by some games.
Small webcam-based PC games are available as either standalone executables or inside web browser windows using Adobe Flash.

Non-real-time webcams
A webcam that records to a video file is essentially no different from any other video camera which records directly to hard disk, including hi-def cameras such as the Thomson Viper, which would never be described as webcams. However, webcam is frequently used to describe any footage shot on the digital video cameras designed for real-time webcam use, recognizable by the distinct quality of image such cameras offer. An example of such webcam use would be in the film Dark Night by Justin Hall.

Technology
Webcams typically include a lens, an image sensor, and some support electronics. Various lenses are available, the most common being a plastic lens that can be screwed in and out to set the camera's focus. Fixed focus lenses are also available, which require no adjustment. Image sensors can be CMOS or CCD, the former being dominant for low-cost cameras, but CCD cameras do not necessarily outperform CMOS-based cameras in the low cost price range. Consumer webcams usually offer a resolution in the VGA region, at a rate of around 25 frames per second. The higher resolution of 1.3 Megapixel is also available from the brands Microsoft, Logitech, and HP.
Support electronics are present to read the image from the sensor and transmit it to the host computer. The camera pictured to the right, for example, uses a Sonix SN9C101 to transmit its image over USB. Some cameras - such as mobile phone cameras - use a CMOS sensor with supporting electronics "on die", i.e. the sensor and the support electronics are built on a single silicon chip to save space and manufacturing costs.
Some webcams feature built in microphones to make video conferencing more convenient. Creative Technology has introduced a webcam featuring built in noise cancellation to focus the audio to the speaker who is directly in front of the camera, excluding ambient noise.
The USB video device class (UVC) specification allows for interconnectivity of webcams to computers even without proprietary drivers installed. Microsoft Windows Vista and Mac OS X 10.5 have UVC drivers built in and do not require extra drivers, although they are often installed in order to add additional features.

Privacy

Some 'Trojan horse' programs can allow malicious hackers to activate a computer's camera without the user's knowledge, providing the hacker with a live video feed from the unfortunate user's camera. Cameras such as Apple's older external iSight cameras include lens covers to thwart this. Most other webcams have a built-in LED that lights up whenever the camera is active.
In mid-January 2005 some search engine queries were published in an on-line forum[4] which allow anyone to find thousands of Panasonic- and Axis-made high-end web cameras accessible through the web. Many such cameras are running on default configuration, which does not require any password login or IP address verification, making them visible to anyone.

Digital Camera

Digital camera

A digital camera is a camera that takes video or still photographs, or both, digitally by recording images on a light-sensitive sensor.
Many compact digital still cameras can record sound and moving video as well as still photographs. In the Western market, digital cameras outsell their 35 mm film counterparts.[1]
Digital cameras can include features that are not found in film cameras, such as displaying an image on the camera's screen immediately after it is recorded, the capacity to take thousands of images on a single small memory device, the ability to record video with sound, the ability to edit images, and deletion of images allowing re-use of the storage they occupied.
Digital cameras are incorporated into many devices ranging from PDAs and mobile phones (called camera phones) to vehicles. The Hubble Space Telescope and other astronomical devices are essentially specialised digital cameras.

Video cameras

Video cameras are classified as devices to record moving images.
Professional video cameras such as those used in television and movie production. These typically have multiple image sensors (one per color) to enhance resolution and color gamut. Professional video cameras usually do not have a built-in VCR or microphone.
Camcorders used by amateurs. They generally include a microphone to record sound, and feature a small liquid crystal display to watch the video during taping and playback.
Webcams are digital cameras attached to computers, used for video conferencing or other purposes. Webcams can capture full-motion video as well, and some models include microphones or zoom ability.
In addition, many live-preview digital cameras have a "movie" mode in which images are continuously acquired at a frame rate sufficient for video.

Live-preview digital cameras

The term digital still camera (DSC) usually implies a live-preview digital camera, which uses an electronic screen, usually a rear-mounted liquid crystal display, as the principal means of framing and previewing before taking the photograph, and for viewing stored photographs. All use either a charge-coupled device (CCD) or a CMOS image sensor to sense the light intensities across the focal plane.
Many live-preview cameras have a movie mode, and many camcorders can take still photographs. However, still cameras take better still photographs than camcorders, and vice versa; there is still a need for distinct still and motion picture cameras.
Images may be transferred to a computer, printer or other device in a number of ways: the USB mass storage device class makes the camera appear to the computer as if it were a disk drive; the Picture Transfer Protocol (PTP) and its derivatives may be used; Firewire is sometimes supported; and the storage device may simply be removed from the camera and inserted into another device.
Live-preview cameras may be compact or subcompact, or the larger and more sophisticated bridge cameras.

Compact digital cameras

Compact cameras are designed to be small and portable; the smallest are described as subcompacts. Compact cameras are usually designed to be easy to use, sacrificing advanced features and picture quality for compactness and simplicity; images can usually only be stored using Lossy compression (JPEG). Most have a built-in flash usually of low power, sufficient for nearby subjects. They may have limited motion picture capability. Compacts often have macro capability, but if they have zoom capability the range is usually less than for bridge and DSLR cameras. They have a greater depth of field, allowing objects within a large range of distances from the camera to be in sharp focus. They are particularly suitable for casual and "snapshot" use.

Bridge cameras

Bridge or SLR-like cameras are higher-end live-preview cameras that physically resemble DSLRs and share with them some advanced features, but share with compacts the live-preview design and small sensor sizes. Fujifilm FinePix S9000
Bridge cameras often have superzoom lenses which provide a very wide zoom range, typically 12:1, which is attained at the cost of some distortions, including barrel and pincushion distortion, to a degree which varies with lens quality. These cameras are sometimes marketed as and confused with digital SLR cameras since the appearance is similar. Bridge cameras lack the mirror and reflex system of DSLRs, have so far been fitted with fixed (non-interchangeable) lenses (although in some cases accessory wide-angle or telephoto converters cannot be attached to the lens), can usually take movies with sound, and the scene is composed by viewing either the liquid crystal display or the electronic viewfinder (EVF). They are usually slower to operate than a true digital SLR, but they are capable of very good image quality while being more compact and lighter than DSLRs. The high-end models of this type have comparable resolutions to low and mid-range DSLRs. Many of these cameras can store images in lossless RAW format as an option to lossy JPEG compression. The majority have a built-in flash, often a unit which flips up over the lens. The guide number tends to be between 11 and 15.

Digital rangefinders

A rangefinder is a user-operated optical mechanism to measure subject distance once widely used on film cameras. Most digital cameras measure subject distance automatically using acoustic or electronic techniques, but it is not customary to say that they have a rangefinder. The term rangefinder alone is sometimes used to mean a rangefinder camera, that is, a film camera equipped with a rangefinder, as distinct from an SLR or a simple camera with no way to measure distance. Information on digital rangefinder cameras specifically is here.
Professional modular digital camera systems
This category includes very high end professional equipment that can be assembled from modular components (winders, grips, lenses, etc.) to suit particular purposes. Common makes include Hasselblad and Mamiya. They were developed for medium or large format film sizes, as these captured greater detail and could be enlarged more than 35 mm.
Typically these cameras are used in studios for commercial production; being bulky and awkward to carry they are rarely used in action or nature photography. They can often be converted into either film or digital use by changing out the back part of the unit, hence the use of terms such as a "digital back" or "film back". These cameras are very expensive (up to $40,000) and are typically not used by consumers.

Line-scan camera systems

A line-scan camera is a camera device containing a line-scan image sensor chip, and a focusing mechanism. These cameras are almost solely used in industrial settings to capture an image of a constant stream of moving material. Unlike video cameras, line-scan cameras use a single array of pixel sensors, instead of a matrix of them. Data coming from the line-scan camera has a frequency, where the camera scans a line, waits, and repeats. The data coming from the line-scan camera is commonly processed by a computer, to collect the one-dimensional line data and to create a two-dimensional image. The collected two-dimensional image data is then processed by image-processing methods for industrial purposes.
Line-scan technology is capable of capturing data extremely fast, and at very high image resolutions. Usually under these conditions, resulting collected image data can quickly exceed 100MB in a fraction of a second. Line-scan-camera–based integrated systems, therefore are usually designed to streamline the camera's output in order to meet the system's objective, using computer technology which is also affordable.
Line-scan cameras intended for the parcel handling industry can integrate adaptive focusing mechanisms to scan six sides of any rectangular parcel in focus, regardless of angle, and size. The resulting 2-D captured images could contain, but are not limited to 1D and 2D barcodes, address information, and any pattern that can be processed via image processing methods. Since the images are 2-D, they are also human-readable and can be viewable on a computer screen. Advanced integrated systems include video coding and optical character recognition (OCR).

Conversion of film cameras to digital

When digital cameras became common, a question many photographers asked was whether their film cameras could be converted to digital. The answer was yes and no. For the majority of 35 mm film cameras the answer is no, the reworking and cost would be too great, especially as lenses have been evolving as well as cameras. For the most part a conversion to digital, to give enough space for the electronics and allow a liquid crystal display to preview, would require removing the back of the camera and replacing it with a custom built digital unit.
Many early professional SLR cameras, such as the NC2000 and the Kodak DCS series, were developed from 35 mm film cameras. The technology of the time, however, meant that rather than being a digital "back" the body was mounted on a large and blocky digital unit, often bigger than the camera portion itself. These were factory built cameras, however, not aftermarket conversions.A notable exception was a device called the EFS-1, which was developed by Silicon Film from c. 1998–2001. It was intended to insert into a film camera in the place of film, giving the camera a 1.3 MP resolution and a capacity of 24 shots. Units were demonstrated, and in 2002 the company was developing the EFS-10, a 10 MP device that was more a true digital back.A few 35 mm cameras have had digital backs made by their manufacturer, Leica being a notable example. Medium format and large format cameras (those using film stock greater than 35 mm), have users who are capable of and willing to pay the price a low unit production digital back requires, typically over $10,000. These cameras also tend to be highly modular, with handgrips, film backs, winders, and lenses available separately to fit various needs.
The very large sensor these backs use leads to enormous image sizes. The largest in early 2006 is the Phase One's P45 39 MP imageback, creating a single TIFF image of size up to 224.6 MB. Medium format digitals are geared more towards studio and portrait photography than their smaller DSLR counterparts, the ISO speed in particular tends to have a maximum of 400, versus 6400 for some DSLR cameras.