Introduction

A type of camera, DSLR stands for Digital Single Lens Reflex instead of the traditional SLR which uses film. In a DSLR, film is replaced by a digital sensor, allowing instant capture and replay like point and shoot cameras. However, the major advantage of a DSLR over cheaper point and shoots is its use of a mirror which reflects incoming light up to the viewfinder via a prism, allowing you to see exactly what the lens sees, avoiding issues such as parallax and in some models allowing you to preview depth of field. When a picture is taken, the mirror flips up, temporarily blocking view from the view finder, and the shutter opens allowing light to hit the sensor. The shutter closes after exposure and the mirror flips back to its normal position once again allowing you to see through the lens.

The secondary advantage of a DSLR is its use of interchangeable lenses, allowing more control over focal length than ever before, it is possible to go from an ultra-wide (8mm fisheye) to long telephoto (500mm or longer) simply by changing the lens. Different companies however, use different lens mounts, so it is not possible to use a Canon lens on a Nikon mount, though a mount adapter may be used some functions such as auto-focus may be disabled. Both primes and zoom lenses are widely available for all mounts.

The sensor, perhaps the most important part of a dslr, comprises of tiny pixels, each made to capture either Red, Green, or Blue, their sensitivity is controlled by the ISO setting of your camera, but since more electricity is passed through the sensor more noise becomes visible. There are different types and sizes of sensors, full frame DSLRs have sensors as large as the original film slr’s format (24X36mm) capture higher amounts of pixels without changing the point of view of the lens. Smaller APS-C sized sensors, while larger than most point and shoots, offer a slightly smaller sensor than their full frame counterparts, this creates a sensor crop factor, cutting the point of view of most lenses by 1.6x, 1.5 or 1.3 (see note 1) depending on the camera model, effectively making the lens longer. The more pixels a sensor has the more resolution and the larger the image size, this is expressed by the term “megapixel” therefore a 16 megapixel camera (referring to the sensor) can print larger than a 6 megapixel camera. Information from the sensor is stored onto media, such as Compact Flash cards, SD cards, Microdrives and others, ranging in size from 16mb to 8gbs, these media store the information from your sensor for later viewing/printing via a computer or printer.

note 1: 1.6x is common for Canon, except the 5D and 1D models. 1.5x is usual for Nikon. 1.3x is found on the Canon 1D mark II and 1D mark III. 1.0x (full frame) is found on the 1D, 1Ds and 5D models.

DSLRs are almost limitless with features, allowing them to be paired up with other accessories such as flash, lens filters, remotes/shutter releases, battery grips, and other types of objects made available by your camera’s maker, and certain third party brands. One of the main features of most DSLRs is the ability to shoot in RAW, allowing you greater control over your images in post processing. These features depend on your camera model, and are not limited to the ones listed above, but these coupled with the points already expressed are the main characteristics that make a DSLR.

none

none

— Mauricio Ubach 2005/10/26 22:20