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How To Buy A Digital SLR Camera

CamerasFeatures
by Jim Fisher, 16 May 2012Features

If you're feeling limited by what your point-and-shoot camera can do, there are plenty of reasons to consider a DSLR. These advanced shooters feature larger image sensors, superior optics, robust manual controls, faster performance, and the versatility of changeable lenses. All this added functionality doesn't come cheap, though, as the cost of a DSLR can add up, especially when you start buying lenses. And the cameras are understandably larger and heavier than their compact and mirrorless interchangeable lens counterparts. You also need to remember that you're buying into a camera system. If your first DSLR is a Canon, chances are that your next one will be as well, simply because you've already bought some Canon lenses and accessories. Here are the most important aspects to consider when you're shopping for a digital SLR:

Understanding sensor size

Most consumer DSLRs use image sensors that, while much larger than those found in point-and-shoot cameras, are somewhat smaller than a 35mm film frame. This can be a bit confusing when talking about a camera's field-of-view, as focal lengths for compacts are often expressed in terms of 35mm film equivalency. The standard APS-C sensor features a "crop factor" of 1.5x (sometimes referred to as the "focal length multiplier"). This means that the 18-55mm kit lens that is bundled with most DSLRs covers a field-of-view equivalent to a 27-82.5mm lens on a 35mm film camera. If you're upgrading from a point-and-shoot that has a 3x zoom lens that starts at about 28mm, the aforementioned DSLR kit lens will deliver approximately the same field-of-view (note: A 1.5x crop factor is not the same as a 1.5x magnification).

There are many inherent advantages to a larger sensor. For one, the depth-of-field decreases as the size of the sensor increases making it easier to isolate your subject and create a blurred background. This blur is often referred to by the Japanese term 'bokeh' and is lens-dependent too. Much has been written about the quality of the bokeh created by different lenses, but the general rule of thumb is that the more light a lens can capture - measured numerically as its aperture, or f-number - the blurrier the background can be. A lens with a maximum aperture of f/1.4 lets in six times as much light as one of f/4, and can create a shallower depth-of-field at an equivalent focal length and shooting distance.

Another reason to go for a bigger sensor is image noise. A 14-megapixel D-SLR has much larger pixels than a point-and-shoot of the same resolution. These larger pixels allow the sensor to be set at a higher sensitivity, measured numerically as ISO, without creating as much image noise. Another advantage to the larger surface area is that changes in colour or brightness are more gradual than that of a point-and-shoot. This allows more natural-looking images with a greater sense of depth.

Some DSLRs, like the Canon EOS 5D Mark III and Nikon D800 feature sensors that are equal in size to 35mm film. These full-frame cameras are much more expensive than their APS-C counterparts. If you do see yourself moving up to a full-frame camera in the future, be careful when buying lenses. Some lenses are specifically designed to be used with APS-C sensors. Canon refers to its APS-C lens line as EF-S, while lenses that cover full-frame are EF. Nikon takes a similar approach, calling APS-C lenses DX and full-frame lenses FX. Sony, the only other manufacturer that currently offers a 35mm full-frame DSLR camera, adds a DT designation to its APS-C-only lenses.

Choose a camera that feels right

It's very important to choose a camera that feels comfortable in your hands. While most DSLRs are similar in size and build, the styling of the handgrip, position of controls, and other ergonomic features can differ drastically. The camera you choose should be one that you are most comfortable using. If a DSLR is too big or small for you to hold comfortably, or if the controls are not laid out in a way that makes sense to you, chances are you won't enjoy shooting as much as you should.

Get the best viewfinder

By definition, a DSLR features an optical viewfinder that shows you the exact image that the camera's sensor will see through the lens - but not all of these viewfinders are created equal. A mirror directs light from the lens to the viewfinder, which is one of two types. The first, the pentamirror, is generally found on entry-level cameras like the Canon EOS 600D and Nikon D5100. This type of viewfinder uses three mirrors to redirect the image to your eye, flipping it so that it appears correct, as opposed to the upside down and backwards image that the lens is actually capturing.

The second type of optical viewfinder is the pentaprism. This is a solid glass prism that does the same job as the pentamirror. A pentaprism is generally heavier and brighter than a pentamirror. The extra brightness makes it easier to frame images and to confirm that your photo is in focus. Pentaprisms usually start appearing in mid-range DSLRs like the Canon EOS 60D, and are standard issue on pro bodies like the Nikon D4.

You should also pay attention to magnification and coverage percentage numbers for pentaprism viewfinders, as they give you an idea of the actual size of the finder and how much of the captured image can be seen. In both cases, you'll want to look for a higher number.

Another option: the electronic viewfinder (EVF)

A few cameras on the market offer a third viewfinder option - an electronic viewfinder. Sony cameras that feature fixed, translucent mirrors, like the Alpha 35, are referred to as SLTs. Rather than redirecting light to your eye, the semi-transparent mirror in these cameras redirects it to an autofocus sensor. If you aren't set on an optical finder, these cameras are worth considering. Models that use OLED EVF technology, like the Sony Alpha 65, produce a viewfinder image that is brighter and crisper than pentamirror finders, but not quite up to the same level of optical quality as a good pentaprism.

Continuous shooting and autofocus speed

DSLRs have another big advantage over point-and-shoot cameras - speed. The time that it takes between hitting the shutter button and the camera capturing a picture, referred to as shutter lag, and the wait time between taking photos - recycle time - are often concerns with compact cameras. DSLRs generally focus very quickly and deliver shutter lag that is nearly immeasurable.

Continuous shooting is measured in frames per second. At minimum, you should look for a camera that can shoot three frames per second, although sports and nature shooters will want to look for a camera that can shoot faster than five frames per second. Of course, the autofocus system has to be able to keep up with the frame rate. Basic DSLRs often only have a few, simple, autofocus points, which can affect performance (especially in low-light conditions). Continuous shooting and autofocus performance go hand-in-hand, so it is important to look for a camera that does both well.

Live view and HD video

Video recording, which was unheard of for DSLRs before the release of the Nikon D90 three years ago, is now a standard feature. When shopping for a DSLR, look for one that autofocuses while recording. You should also check its autofocus speed when taking photos using live view, as that can often be very slow. A microphone input jack is important if you plan on using the video function often - an external mic will capture much better sound than the camera's built-in microphone.

Be realistic about lenses and accessories

Most first-time DSLR users aren't going to purchase a whole bevy of lenses, but there are a few to consider to supplement the kit lens that typically ships with the camera. The first is a telezoom to complement the standard 18-55mm lens. There is usually a matching zoom, starting at 55mm and ranging up to 200mm or 300mm, which will help you get tighter shots of distant action. Plan on budgeting £200-£300 for this lens.

Another popular lens choice is a fast, normal-angle prime lens. Before zooms were popular, film SLRs were often bundled with a 50mm f/2 lens. Because of the smaller sensor in consumer DSLRs, a 35mm f/2 is the current equivalent. The normal-angle gives you a field-of-view that is not far off from that of your eye, and the fast aperture makes it possible to shoot in lower light, and to isolate your subject by blurring the background of your photos. Prices for these lenses vary a bit depending on your camera system, but expect it to be between £100 and £300. 

Even though many consumer DSLRs have built-in flashes, many photographers opt to use a more powerful external flash. These flashes emit more light and can often be repositioned so that you can use reflected light to illuminate a subject. Bouncing flash off a ceiling to brighten a room is possible with a dedicated flash unit, but not with the ubiquitous DSLR pop-up flash. Depending on your needs for power, recycle time, and movement, dedicated flash units can cost anywhere from £120 to £600.

Is a DSLR too big?

Want speed and top-notch images, but don't want to haul a heavy DSLR? You may also want to consider a Compact Interchangeable Lens (CILC) camera, like Sony's Alpha NEX-C3. That camera packs the same APS-C sensor found in a DSLR into a more compact package, but it lacks an optical or electronic viewfinder - you'll need to use the rear LCD to frame photos. This newer class of cameras, which launched by Olympus and Panasonic with the Micro Four Thirds standard, relies on live view rather than optical viewfinders. This makes it possible to pack larger sensors into smaller bodies, giving you many of the image quality advantages of a DSLR without the added bulk.

You'll want to pay attention to sensor size, as they vary between formats - Micro Four Thirds cameras and the Nikon J1 system feature sensors that are smaller than those in a DSLR, and the tiny Pentax Q uses a point-and-shoot-sized image sensor, but adds the benefit of interchangeable lenses. You won't save a huge amount of money on a CILC, as current models are typically priced around £350 to £900, with most in the middle of that range. However, if you're willing to skip the traditional optical viewfinder, a mirrorless camera might strike the perfect balance between point-and-shoot and digital SLR.

If you do opt for a DSLR, following our guidelines will help you to choose the camera and lens system that fits your needs and your budget. Just be sure to take time and research your purchase, and go to the store and pick up a couple of cameras to see which feels best.

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