DSLR Buying Guide - Basics

A Digital SLR or DSLR is a digital camera with a single interchangeable lensThis is currently the case but has not always been so. that is used for both recording and framing an image. It does so thanks to a mirror that reflects light to an optical viewfinder and moves out of the way to capture images. DSLR therefore stands for Digital Single Lens Reflex.

DSLR cameras are built differently than fixed-lens digital camerasOften incorrectly called Point&Shoot digital cameras, of which only some are.. Given that SLRs must be a certain size to accommodate a moving mirror and optical viewfinder, they always use large imaging sensors. This makes them advantageous in terms of image quality, particularly in low-light when high-sensitivities exasperate image-noise. Their size also makes it easier to include powerful components and high-end features.

A DSLR also differs from Mirrorless CamerasPreviously known as SLD or Single Lens Digital. which were invented to bridge the gap between compact cameras and DSLRs. Some Mirrorless cameras have sensors of the same size as DSLRs and are therefore capable of the same image quality. Since they do not use a reflex mirror, mirrorless cameras can be made smaller but they cannot provide an optical viewfinder to frame with.

Today's digital SLR cameras all have interchangeable lenses. While this provides great flexibility, choosing the right lens or set of lenses can be more difficult than choosing the right DSLR.

The third page of this DSLR Buying Guide shows all current DSLRs. For the list both current and discontinued models, go to the DSLR listing page.

These are the 10 most important things to know about Digital SLR cameras. There are critical difference between DSLRs and other types of digital cameras, so be sure to understand these before comparing and shopping for a DSLR, particularly if it will be your first.

• Digital SLR cameras are most efficient when using their OVF. Even though modern DSLRs feature Live-View which enables the rear LCD to show an approximation of the scene, autofocus slows down considerably on most models with a noticeable shutter-lag, plus the preview is rarely WYSIWYG.
• DSLR viewfinders see through the lens. This makes it easy to judge focus - but neither exposure nor white-balance - through it. One cannot see if a picture will be over-exposed or under-exposed or have a color-cast before taking it.
• Optical Zoom depends on the lens attached to the camera. It makes no sense to specify optical zoom when describing a digital SLR camera. Some lenses do not zoom and are called prime lenses.
• The angle-of-view of a lens depends on the Crop-Factor or FLM of the camera it is mounted on. The Crop-Factor of a DSLR is determined by the size of its imaging sensor. Both Crop-Factor and Focal-Length-Multiplier mean exactly the same thing and are measured in relation to 35mm film.
• The connector between an SLR camera and a lens is called a mount. Only SLR cameras and lenses with the same mount can be attached together. Even if a lens attaches, it may not fully work. Lenses lose autofocus sometimes. A lens designed for a too small sensor will clip large parts of the image.
• SLR lenses are almost always zoomed and manually focused by hand. This is infinitely precise, considerably faster and much more responsive than the power-zoom and electronic focus used on nearly all fixed-lens cameras.
• DSLR cameras are powerful photographic tools. All currently feature full manual-controls, manual-focus, custom white-balance, choice of metering patterns, continuous drive, high-ISO sensitivities, a hot-shoe for an external flash and support RAW capture. Most current models also have automatic dust-reduction, white-balance fine-tuning, and a fully automatic mode as well.
• Available apertures are determined by the attached lens. A lens prominently specifies its maximum aperture at both ends of the zoom, if applicable. Available shutter-speeds and ISO sensitivities are determined by the camera and are usable at any aperture on all lenses. All shutter-speeds are not compatible with electronic flash though, including the built-in one, when applicable.
• Nearly all DSLRs from 2010 onward can record video. DSLR video quality is very good with a shallow cinematic depth-of-field. Autofocus while filming is usually supported but the contrast-detect AF-system used by most DSLRs is problematic and depth-of-field exaggerates the problem.
• Battery life on a DSLR is significantly longer than most fixed-lens digital cameras unless Live-View or video-capture is used. That happens because the LCD consumes a lot of power and the imaging sensor needs to be constantly active.