Digital Single-lens Reflex Camera - DSLRs Compared To Other Digital Cameras

DSLRs Compared To Other Digital Cameras

The reflex design scheme is the primary difference between a DSLR and other digital camera. In the reflex design scheme, the image captured on the camera's sensor is also the image that is seen through the view finder. Light travels through a single lens and a mirror is used to reflect a portion of that light through the view finder - hence the name Single Lens Reflex. While there are variations among point-and-shoot cameras, the typical design exposes the sensor constantly to the light projected by the lens, allowing the camera's screen to be used as an electronic viewfinder. However, LCDs can be difficult to see in very bright sunlight.

Compared to some low cost cameras that provide an optical viewfinder that uses a small auxiliary lens, the DSLR design has the advantage of being parallax-free: it never provides an off-axis view. A disadvantage of the DSLR optical viewfinder system is that when it is used, it prevents using the LCD for viewing and composing the picture. Some people prefer to compose pictures on the display – for them this has become the de facto way to use a camera. Depending on the viewing position of the reflex mirror (down or up), the light from the scene can only reach either the viewfinder or the sensor. Therefore, many early DSLRs did not provide "live preview" (i.e., focusing, framing, and depth-of-field preview using the display), a facility that is always available on digicams. Today most DSLRs can alternate between live view and viewing through an optical viewfinder.

The larger, advanced digital cameras offer a non-optical electronic through-the-lens (TTL) view, via an eye-level electronic viewfinder (EVF) in addition to the rear LCD. The difference in view compared to a DSLR is that the EVF shows a digitally created image, whereas the viewfinder in a DSLR shows an actual optical image via the reflex viewing system. An EVF image has lag time (that is, it reacts with a delay to view changes) and has a lower resolution than an optical viewfinder but achieves parallax-free viewing using less bulk and mechanical complexity than a DSLR with its reflex viewing system. Optical viewfinders tend to be more comfortable and efficient, especially for action photography and in low-light conditions. Compared to digital cameras with LCD electronic viewfinders, there is no time lag in the image: it is always correct as it is being "updated" at the speed of light. This is important for action or sports photography, or any other situation where the subject or the camera is moving quickly. Furthermore, the "resolution" of the viewed image is much better than that provided by an LCD or an electronic viewfinder, which can be important if manual focusing is desired for precise focusing, as would be the case in macro photography and "micro-photography" (with a microscope). An optical viewfinder may also cause less eye-strain. However, electronic viewfinders may provide a brighter display in low light situations, as the picture can be electronically amplified.

DSLR cameras often have image sensors of much larger size and often higher quality, offering lower noise, which is useful in low light. Although mirrorless digital cameras with sensors as large as APS-C size are now commonly available, larger sizes such as full frame and medium format sized image sensors are only seen in DSLR designs.

DSLRs generally offer faster and more responsive performance, with less shutter lag, faster autofocus systems, and higher frame rates. Other digital cameras were once significantly slower in image capture (time measured from pressing the shutter release to the writing of the digital image to the storage medium) than DSLR cameras, but this situation is changing with the introduction of faster capture memory cards and faster in-camera processing chips. Still, compact digital cameras are not suited for action, wildlife, sports and other photography requiring a high burst rate (frames per second).

Simple point-and-shoot cameras rely almost exclusively on their built-in automation and machine intelligence for capturing images under a variety of situations and offer no manual control over their functions, a trait which makes them unsuitable for use by professionals, enthusiasts and proficient consumers (aka "prosumers"). Bridge cameras provide some degree of manual control over the camera's shooting modes, and some even have hotshoes and the option to attach lens accessories such as filters and secondary converters. DSLRs typically provide the photographer with full control over all the important parameters of photography and have the option to attach additional accessories including hot shoe-mounted flash units, battery grips for additional power and hand positions, external light meters, and remote controls.

DSLRs have a larger focal length for the same field of view, which allows creative use of depth of field effects. However, small digital cameras can focus better on closer objects than typical DSLR lenses.

Unlike DSLRs, most digital cameras lack the option to change the lens. Instead, most compact digital cameras are manufactured with a zoom lens that covers the most commonly used fields of view. Having fixed lenses, they are limited to the focal lengths they are manufactured with, except for what is available from attachments. Manufacturers have attempted (with increasing success) to overcome this disadvantage by offering extreme ranges of focal length on models known as superzooms, some of which offer far longer focal lengths than readily available DSLR lenses.

The mirror movement in reflex cameras causes vibrations. These vibrations may result in unsharp pictures when taking pictures through microscopes or telescopes. Mechanical shutters may also contribute vibrations. mirrorless interchangeable lens cameras have no mirror, hence less vibrations.

However, since the introduction of the Micro Four Thirds system by Olympus and Panasonic in late 2008, mirrorless interchangeable lens cameras are now widely available so the option to change lenses is no longer unique to DSLRs. Cameras for the micro four thirds system are designed with the option of a replaceable lens and accept lenses that conform to this proprietary specification. Cameras for this system have the same sensor size as the Four Thirds System but do not have the mirror and pentaprism, so as to reduce the distance between the lens and sensor.

Panasonic released the first Micro Four Thirds camera, the Lumix DMC-G1. Several manufacturers have announced lenses for the new Micro Four Thirds mount, while older Four Thirds lenses can be mounted with an adapter (a mechanical spacer with front and rear electrical connectors and its own internal firmware). A similar mirror-less interchangeable lens camera, but with an APS-C-sized sensor, was announced in January 2010: the Samsung NX10. On 21 September 2011, Nikon announced with the Nikon 1 a series of high-speed MILCs. A handful of rangefinder cameras also support interchangeable lenses. Five digital rangefinders exist: the Epson R-D1 (APS-C-sized sensor), the Leica M8 (APS-H-sized sensor), both smaller than 35 mm film rangefinder cameras, and the Leica M9, M9-P and M Monochrom (all full-frame cameras, with the Monochrom shooting exclusively in black-and-white).

In common with other interchangeable lens designs, DSLRs must contend with potential contamination of the sensor by dust particles when the lens is changed (though recent dust reduction systems alleviate this). Digital cameras with fixed lenses are not usually subject to dust from outside the camera settling on the sensor.

DSLRs generally have greater cost, size, and weight. They also have louder operation, due to the SLR mirror mechanism. Sony's fixed mirror design manages to avoid this problem. However, that design has the disadvantage that some of the light received from the lens is diverted by the mirror and thus the image sensor receives about 30% less light compared to other DSLR designs.