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 quite different from fixed-lens digital camerasOften incorrectly called Point&Shoot digital cameras, of which only some are.. Since SLRs are a certain size to accommodate the moving mirror and optical viewfinder, they always use large imaging sensors. This gives them an advantage in terms of image quality, particularly when it comes to image noise at high-sensitivities. Their size also makes it easier to include powerful components and high-end features.

A DSLR also differs from a Mirrorless cameraPreviously known as SLD or Single Lens Digital. which are designed to bridge the gap between compact cameras and DSLRs. Some Mirrorless cameras have sensors of the same size as DSLRs and therefore have similar image quality. They do not use a reflex mirror which lets them be smaller yet do not provide an optical view 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. Most autofocus lenses as well as some not-too-old manual focus film SLR lenses can be used on a DSLR but often show a different angle-of-view.

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

Here are the 10 most important things to know about Digital SLR cameras. 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 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 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 electronic zoom and 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. The video quality is high and well regarded because of its cinematic shallow depth-of-field. Autofocus during video is possible on some models but the contrast-detect method used remains currently problematic and depth-of-field exaggerates the problem. Professional quality videos must be focused by hand.
• 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.

SLT - Almost DSLR and Almost Mirrorless

Sony makes cameras the size and shape of DSLRs which use the same sensors and lenses. They call these SLT cameras for Single Lens Translucent. They use a semi-transparent mirror to reflect around 30% of light to focus and metering sensors. Contrarily to an SLR, an SLT has an EVF. This viewfinder can preview exposure, color, white-balance and focus, up to its maximum precision.

Facts 1 & 2 above do not apply to Sony SLT cameras and neither does fact 10. Facts 3 to 8 remain applicable though. As for fact 9, Sony SLT cameras are unique in that they can match the video quality of DSLRs and use Phase-Detect autofocus completely. Newer DSLRs are appearing with hybrid systems, so improvements may come soon.

The best way to understand an SLT camera is to see it as an over-sized mirrorless with fast autofocus. Search for current Sony SLT cameras here. These are compatible with Alpha lenses from Sony and Konica-Minolta.