Digital single-lens reflex camera

A digital single-lens reflex camera (digital SLR or DSLR) is a digital camera. It uses the same parts as a single-lens reflex camera but has a special image sensor to record pictures digitally.

The main difference between a DSLR and other digital cameras is its reflex design. In this design, light goes through the lens to a mirror. The mirror moves to show the image either in a prism, which you see through the optical viewfinder, or on the camera's sensor when you press the button to take a picture. The viewfinder shows you almost exactly what the camera will capture, because it uses the main lens directly.

DSLRs replaced film cameras in the 2000s. Starting in the 2010s, many camera makers began making mirrorless interchangeable-lens cameras instead.

History

See also: History of the camera § Digital cameras

In 1969, Willard S. Boyle and George E. Smith found a new way to take pictures using tiny parts. This helped create digital photos. They won a special award called the Nobel Prize in 2009.

In the 1970s and 1980s, companies began making cameras that saved pictures digitally instead of on film. These early cameras looked like old film cameras but used special parts.

Sony showed a new camera in 1981 that used a special disk to save pictures. It was one of the first cameras that didn’t use film.

In 1986, a company called Kodak made a camera that could save digital pictures. It was one of the first real digital cameras.

Over time, many companies made digital cameras that worked like old film cameras but saved pictures digitally. These are called digital SLRs.

In the late 1990s, Nikon made a professional digital camera that could use the same lenses as their film cameras. This helped digital cameras become popular with professionals.

In the 2000s, more companies started making digital SLRs for everyday users. These cameras became easier to buy and use, so more people could take digital pictures.

Today, digital SLRs are still used by many people, but many companies now make cameras without mirrors, called mirrorless cameras. Nikon and Pentax still make some digital SLRs, while others have stopped.

• Nikon offers the flagship full-frame D6, as well as the midrange full-frame D780 and D850 and the entry-level APS-C D7500. As of 2024^[update], all other Nikon DSLRs have been discontinued.
• Leica produces the S3, a medium format DSLR.
• Pentax currently offers APS-C and full-frame DSLRs. The APS-C cameras include the K-3 III and the KF. The K-1 Mark II, announced in 2018 as successor to the Pentax K-1, is the current full-frame model. All APS-C and full-frame models have extensive backward compatibility with Pentax and third-party film era lenses from about 1975, those that use the Pentax K mount.

Design

DSLRs often use interchangeable lenses that fit into a special lens mount. Inside the camera, there is a moving mirror that flips up and down. When you look through the viewfinder, the mirror sends light through a special glass block called a pentaprism or pentamirror, showing you exactly what the lens sees.

To take a picture, the mirror moves out of the way, the focal-plane shutter opens, and the image is captured by the image sensor. After the picture is taken, the mirror moves back, ready for the next shot. This mirror system lets you see a clear, bright preview of your scene before taking the picture.

Autofocus

Main article: Phase detection autofocus

DSLRs usually use a special focusing method called phase detection. This helps the camera quickly find the best focus point.

Common features

Mode dial

Digital SLR cameras, like most other digital cameras, usually have a mode dial to choose different camera settings or automatic scene modes. Sometimes called a "PASM" dial, they often include modes such as program, aperture-priority, shutter-priority, and full manual modes. Scene modes can change depending on the camera and are less customizable. They often include landscape, portrait, action, macro, night, and silhouette, among others. These different settings can also be set up by adjusting certain camera options.

Dust reduction systems

Main article: Dust reduction system

One way to keep dust out of the camera is by using a "dust cover" filter behind the lens mount. This was first used by Sigma in its first DSLR, the Sigma SD9, in 2002.

Olympus used a built-in sensor cleaning tool in its first DSLR, the Olympus E-1, in 2003, which had a sensor that could be exposed to air.

Several Canon DSLR cameras use a system that shakes the sensor at high speeds to remove dust.

Interchangeable lenses

Main articles: Photographic lens and Lenses for SLR and DSLR cameras

Changing lenses to pick the best one for what you’re taking a picture of is a big reason why DSLR cameras are popular, even though this feature isn’t only for DSLRs. Interchangeable lenses for SLRs and DSLRs are made to fit a specific lens mount, which is usually different for each brand. Photographers often use lenses made by the same company as the camera body, like Canon EF lenses on a Canon camera, but there are also many other companies, such as Sigma, Tamron, Tokina, and Vivitar, that make lenses for different lens mounts. There are also lens adapters that let you use a lens made for one mount on a camera with a different mount, though this can sometimes limit what the lens can do.

Many lenses can be used on modern DSLRs and older film SLRs that use the same lens mount. However, when lenses made for 35 mm film or similarly sized digital sensors are used on DSLRs with smaller sensors, the image gets "cropped," and the lens seems to have a longer focal length than it actually does. Most DSLR makers have created lenses designed for smaller sensors, mostly in the wide-angle range. These lenses might not work fully with full-frame sensors or 35 mm film because of the smaller image circle, and some Canon EF-S lenses can interfere with the mirror inside full-frame cameras.

HD video capture

Since 2008, makers have added a movie mode to DSLRs that can record high-definition video. A DSLR with this feature is often called an HDSLR or DSLR video camera. The first DSLR with HD movie mode was the Nikon D90, which recorded video at 720p24 (1280x720 resolution at 24 frame/s). Other early HDSLRs used unusual video resolutions or frame rates. For example, the Pentax K-7 used a resolution of 1536×1024, matching the imager’s 3:2 aspect ratio. The Canon EOS 500D (Rebel T1i) used a frame rate of 20 frame/s at 1080p, along with a more standard 720p30 format.

Generally, HDSLRs use the whole sensor to capture HD video, though not all pixels are used (which can cause some video issues). Compared to the small sensors in most camcorders, HDSLRs have much larger sensors, giving them different image qualities. HDSLRs can create shallower depth of field and better performance in low light. However, because of how they’re built, HDSLRs often lack some video features found in regular camcorders. These limitations mean HDSLRs need some planning and skill to use for filming.

Video features in HDSLRs have kept improving, with higher resolutions (like 1080p24), better automatic and manual controls, and support for formats used in high-definition TV, Blu-ray discs, and Digital Cinema Initiatives (DCI). The Canon EOS 5D Mark II (with firmware version 2.0.3/2.0.4) and Panasonic Lumix GH1 were the first HDSLRs to offer 1080p video at 24 frames per second, and since then many more models have added similar features.

The growth of HDSLR cameras has led to a new era in digital filmmaking. Many independent filmmakers use these cameras. HDSLRs are also used in documentary filmmaking because they’re affordable, have good technical and visual features, and allow for very personal filming. More films, TV shows, and other projects are using these improving features. Because HDSLRs are more affordable and smaller than professional movie cameras, The Avengers used five Canon EOS 5D Mark II and two Canon 7D to film scenes from different angles.

Makers have created optional accessories to improve DSLRs for video, such as shotgun microphones and external EVF screens with 1.2 million pixels.

Live preview

Main article: Live preview

Early DSLRs couldn’t show the view through the optical viewfinder on the LCD screen — a feature called live preview. Live preview is helpful when the camera’s viewfinder can’t be used, such as in underwater photography where the camera is in a waterproof case.

In 2000, Olympus introduced the Olympus E-10, the first DSLR with live preview, though it had a fixed lens. By late 2008, many DSLRs from Canon, Nikon, Olympus, Panasonic, Leica, Pentax, Samsung and Sony offered continuous live preview. The Fujifilm FinePix S5 Pro allowed 30 seconds of live preview.

On most DSLRs with live preview using the main sensor, the autofocus system that uses phase detection doesn’t work in live preview mode, and the camera switches to a slower contrast system, like in point-and-shoot cameras.

In 2012, Canon introduced hybrid autofocus to DSLRs with the EOS 650D/Rebel T4i, and later a more advanced version called “Dual Pixel CMOS AF” with the EOS 70D. This technology lets certain pixels do both contrast detection and phase detection, making autofocus faster in live view.

A separate software tool from Breeze Systems, called “DSLR Remote Pro v1.5,” introduced in October 2007, allows live view from a distance. It works with the Canon EOS 40D and 1D Mark III.

Sensor size and image quality

Main article: Image sensor format

Image sensors in DSLRs come in different sizes. The largest are used in “medium format” cameras, usually with a “digital back,” which can replace a film back.

“Full-frame” sensors are the same size as 35 mm film (24×36 mm). They’re used in DSLRs like the Canon EOS-1D X Mark II, 5DS/5DSR, 5D Mark IV and 6D Mark II, and Nikon’s D5, D850, D750, D610 and Df. Most cheaper DSLRs use a smaller sensor called APS-C, which is about 24×16 mm, slightly smaller than an APS-C film frame. Other sensor sizes in DSLRs include the Four Thirds System sensor, APS-H sensors, and the original Foveon X3 sensor. Leica has an "S-System" DSLR with a 30×45 mm sensor.

The number of megapixels in a DSLR sensor is a measure of resolution. More expensive cameras and those with larger sensors often have higher megapixel counts. But more megapixels don’t always mean better quality.

Depth-of-field control

The lenses used on DSLRs often have a wider range of apertures.

Wider angle of view

Further information: Crop factor

The angle of view of a lens depends on its focal length and the size of the camera’s image sensor. As of 2017, only a few DSLRs had full-frame sensors, such as the Canon EOS-1D X Mark II, EOS 5D Mark IV, EOS 5DS/5DS R, and EOS 6D Mark II; Nikon’s D5, D610, D750, D850, and Df; and the Pentax K-1. The limited number of full-frame DSLRs is partly because of the cost of such large sensors.

The effect of sensor size on angle of view is called the “crop factor.” This is the number you multiply the lens focal length by to get the full-frame-equivalent focal length. Typical APS-C sensors have crop factors of 1.5 to 1.7.

Unusual features

On July 13, 2007, FujiFilm announced the FinePix IS Pro, which used Nikon F-mount lenses. This camera could also capture images in infrared and ultraviolet light.

In August 2010, Sony released a series of DSLRs that allowed 3D photography. This was done by moving the camera horizontally or vertically in Sweep Panorama 3D mode. The image could be saved as an ultra-wide panoramic picture or as 16:9 3D photography to be viewed on BRAVIA 3D TV sets.

Comparison with other digital cameras

The main difference between a digital single-lens reflex camera (DSLR) and other digital cameras is its design. In a DSLR, the same light that reaches the camera’s sensor also goes through the viewfinder. This uses a mirror that moves up and down. When you press the shutter button, the mirror moves away so light can reach the sensor and take the picture.

Other digital cameras, like point-and-shoot cameras, usually show the picture on an LCD screen. This screen can be hard to see in bright sunlight. DSLRs show the picture through an optical viewfinder, which does not get washed out by sunlight and works very fast. However, when you use the optical viewfinder, you cannot see the picture on the screen at the same time. Some DSLRs now have “live preview,” which lets you see the picture on the screen, but older models did not have this feature.