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.
Top 10 DSLR Facts
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.
DSLR cameras are most regarded for their high image quality, although it is strongly affected by the choice of lens. A combination of low image noise, high retention of details and wide dynamic-range, places these digital cameras ahead. This lead is even more significant at high ISO sensitivities commonly used for low-light hand-help photography.
The vast majority of fixed-lens cameras use significantly smaller sensors. The few exceptions produce similar image quality and those make excellent choices to obtain high image-quality without the bulk or complexity of a DSLR. This search finds all fixed-lens cameras using the same sensor-size a DSLR.
Mirrorless cameras which often use the same sensor-size produce images of similar quality. They save bulk but not complexity. These cameras still feature interchangeable lenses and photographic controls, although lower end models make them considerably less accessible.
The most significant performance advantage of a DSLR is in terms of speed. Compared to fixed-lens cameras, a DSLR focuses faster and shoots faster for longer. Most other timings are noticeably faster too, including the shot-to-shot delay and startup time. Compared to the latest mirrorless cameras, DSLRs are still ahead overall but the gap is closing. Autofocus speeds on some models matches entry-level to mid-range DSLRs when light levels are not too low.
Focusing speed is important when capturing a moving subject. The faster a camera can focus, the faster it will take a picture. Shot-to-shot times and burst speed are generally faster at maximum resolution on a DSLR, but there are much faster CMOS-based fixed lens cameras now. Burst-mode is mostly used in action and fashion photography where capturing a precise moment is paramount. Not only do DSLRs shoot faster, they also take more shots in a single burst at constant speed. This increases the chances of capturing a decisive moment.
Interchangeable lenses are no longer unique to DSLRs but they remain one of their greatest strengths. They bring versatility for framing and isolating subjects thanks to the shallow depth-of-field provided by bright lenses in combination with large sensors. SLR lenses have existed far longer than mirrorless ones and the choice of native lensesPentax K and Sony SLT exceptionally use the same lenses as DSLRs. Others have their own lens-mounts but can use DSLR lenses with some restrictions using adapters. is immensely greater for the former.
DSLR cameras, like everything else, have issues proper to them. The two main issues are price and sensor dust. Even the cheapest DSLR is priced above nearly all fixed-lens digital cameras when one or more lens is included. Mirrorless cameras on average are priced below DSLRs but there are plenty of entry-level DSLRs which cost less than a good number of mirrorless cameras.
To get the best image quality out of a DSLR, one needs to buy good quality lenses. Often such lenses cost at least the same price as the camera. Quality lenses either do not zoom or do so within a short range, so it can take quite a few lenses to cover your needs and this multiples costs.
Sensor dust is simply dust that enters into a digital SLR while the lens is being changedThis cannot really happen with a fixed-lens camera.. One way to minimize it is to buy a single versatile lens and leave it permanently on. Most recent DSLRs also incorporate a mechanism designed to shake-off sensor dust. This reduces the problem without eliminating it completely.
By far the greatest complaint about DSLR cameras is bulk. Even the smallest DSLR is big. Attach a lens and it gets bigger. Take more lenses with you and things get bigger and heavier and telephoto lenses are particularly long. All together this means that using a DSLR requires a commitment to carry that much bulk around. After all, if it is inconvenient to carry, it often stays home and takes fewer pictures. Bulk is even more important a factor for travel photography.
The size of DSLRs contributes to its effect on people in both positive and negative ways. On the positive side, it gives the impression of professionalism. This same aspect also has negative side-effects: It attracts a lot more attention and makes people more self-aware, reducing opportunities for candid photography. In some areas, it easily attracts the attention of the wrong type of people.
Minor issues of DSLR cameras include the limited live-view functionality and shutter-sound. One cannot always preview how a picture will be exposed. Instead, metering and experience must be relied upon. DSLR cameras have a much louder shutter soundDue to the moving mirror and larger focal-plane shutter. than fixed-lens digital cameras. This can be disruptive in quiet environments or when discretion is required. Mirrorless cameras are quieter than DSLR and those with an electronic-shutter even more so.
New Cameras & Lenses
Sony Alpha SLT-A5820 Megapixels Mirrorless (SLD)
Sony Alpha Lens Mount
Nikkor 1 32mm F/1.2Nikon 1 Mount Prime Lens
Canon EF 200-400mm F/4L IS USM 1.4XStabilized & Weatherproof
Canon EF Mount Zoom
Olympus PEN E-PL616 Megapixels Mirrorless (SLD)
Micro Four-Thirds Lens Mount
Olympus PEN E-P516 Megapixels Mirrorless (SLD)
Micro Four-Thirds Lens Mount
Sigma DN 60mm F/2.8Sony E Mount Prime Lens
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