Digital DNA

Unless you’re already committed to a specific brand through years of lens and accessory purchases, buying a new DSLR today may mean comparing a dozen models. And even if you’re settled on a camera family, picking the right model from the tree isn’t always apples to apples. In the days of film, there really was only one dominant format: 35mm. With digital, there are four formats, eight major manufacturers and multiple models to sort through.

To help you get some perspective on the decision and get an idea of what to expect from a given system and manufacturer, it helps to know a bit of the history of the brand and how current models within each lineup compare. While you generally can expect cameras in a given price range to have similar features, there are key differences between the camera families that may be the deciding factor for you.


Canon’s DSLRs can trace their roots to the company’s EOS film cameras, the first of which was introduced in 1987. The EOS system was based around a new electronic lens mount, with an AF motor in each EF lens, while other manufacturers adapted their existing SLR systems to autofocus use, with AF motors in the camera body rather than the lens. Note that all major DSLR manufacturers now offer a number of lenses with onboard AF motors.

All EOS DSLRs feature the EOS electronic lens mount and can use all EOS EF lenses (but note that only APS-C-sensor EOS DSLRs can use EF-S lenses, which were designed specifically for the smaller APS-C-format sensors). Current EOS DSLRs feature 14-bit A/D conversion, which can reproduce 16,384 gradations of tone or color versus 4,096 gradations with 12-bit images. All current EOS DSLRs also feature Canon’s self-cleaning sensor system to keep dust off the low-pass filter that covers the sensor assembly.

Canon DSLRs also feature CMOS sensors designed and produced by Canon, and all since the EOS 50D feature Canon’s powerful DIGIC 4 image processor.

Canon EOS-1D Mark IV

The Mark IV is the newest member of Canon’s EOS-1 series of all-out pro cameras. Its forte is speed—both shooting (10 fps at full 16.1-megapixel resolution) and ISO (normal range 100-12,800, expandable to 50-102,400). Image quality and AF performance are excellent.

Carrying on the EOS-1 tradition, the Mark IV is an exceptionally rugged pro camera, with a magnesium-alloy chassis, a mirror box, top, front and rear covers that seal against dust and water, and a 300,000-cycle shutter. Add a weatherproof L-series lens and an EX-series Speedlite, and the entire system is rain-resistant.

All recent EOS DSLRs use the DIGIC 4 processor, but the Mark IV has two of them (as does the 7D). This provides operational speed and the processing power to employ highly effective noise reduction and image-processing algorithms. The Mark IV can do 1080 HD video at 24, 25 and 30 fps, and 720p HD video at 60 and 50 fps.

Canon EOS 5D Mark II

The original 5D was the first “affordable” full-frame DSLR, and its successor, the 5D Mark II, was the first full-frame DSLR to offer video capability. The Mark II was quickly adopted by many video shooters as well as still photographers.

Originally, the 5D Mark II offered limited video capability by today’s standards, but firmware upgrades have raised it to match the video features of Canon’s newer video DSLRs. The reasons for its popularity as a video device are its huge image sensor (by video standards) and the “cinematic” depth of field it creates, its high-ISO/low-light shooting capability, its ability to do video with the full range of EOS EF lenses, and its small size and low price for a pro video device.

As a still camera, the 5D Mark II offers a 21.1-megapixel, full-frame CMOS sensor with even better image quality than that of Canon’s flagship EOS-1Ds Mark III (thanks in large part to the DIGIC 4 image processor introduced a few months earlier in the 50D, plus technological improvements in the sensor). It can shoot those huge images at 3.9 fps and, while not as rugged as the EOS-1D series, features a stainless-steel chassis with magnesium-alloy covers and a shutter tested to 150,000 cycles.

Canon EOS 7D

Canon’s top APS-C model, the 7D features two DIGIC 4 processors like the EOS-1D Mark IV, and even more pixels, with an 18-megapixel CMOS sensor. It can shoot those big images at up to 8 per second and, with what’s probably the company’s most versatile AF system, it’s a fine action camera.

Besides the new 19-point AF system with several new AF-point configurations, the 7D introduced Canon’s new 63-zone dual-layer metering system, now also employed by the 60D and Rebel T2i.

As one would expect of a mid-level EOS DSLR, the 7D features a rugged, yet lightweight magnesium-alloy chassis with good sealing against dust and moisture.

Canon EOS 60D

Although its name suggests that it’s the successor to the 50D, the 60D is probably best thought of as a “super” Rebel. The first EOS to offer a tilting/swiveling LCD monitor, the 60D has a polycarbonate shell over an aluminum-alloy body versus the magnesium-alloy bodies of the 50D and its predecessors.

The 60D inherits the new 63-zone, dual-layer metering system introduced in the 7D and the 9-point all-cross-type AF system of the 50D (but with a new AI Servo AF II algorithm for improved performance). The camera accepts the same interchangeable focusing screens as the 50D. The exposure-compensation range has been increased to +/-5 stops, a valuable improvement.

Canon EOS Rebel T2i

Canon’s entry-level DSLRs have been popular from the introduction of the original EOS Digital Rebel in 2003—the first DSLR to sell for under $1,000. Today, you can purchase a number of DSLRs for under $1,000, and the newest Rebel, the T2i, is among the best. It features an 18-megapixel sensor like the 7D and 60D, a DIGIC 4 processor and full HD video. It also features the 63-zone dual-layer metering system introduced in the 7D and the 9-point AF system used in the 50D.


Canon offers an extensive array of lenses for its DSLRs. The APS-C models can use all of them; the larger-sensor cameras can’t use the EF-S lenses, which were designed specifically for the smaller sensors.

There are more than 60 lenses in the lineup, from an 8-15mm fisheye zoom to an 800mm ƒ/5.6 supertelephoto, including more than 20 with built-in image stabilizers (these are designated “IS”). Four manual-focus TS-E lenses provide tilt-shift capability. There are also 1.4x and 2x teleconverters.


Canon offers an extensive array of lenses for its DSLRs. The APS-C models can use all of them; the larger-sensor cameras can’t use the EF-S lenses, which were designed specifically for the smaller sensors.

Accessories for the EOS DSLRs include flash units (pro through economy-level, plus macro twin and ringlight), remote controls, angle finders, battery grips and wireless file transmitters, handy for photojournalists. The battery grips hold one or two standard lithium-ion batteries to extend shooting capacity and permit shooting with AA batteries. The grips also provide controls for easier vertical-format shooting and added bulk that provides better balance when using long lenses./td>


Nikon has produced some 27 DSLRs since the D1 was introduced in 1999, and the current lineup benefits from all the company has learned along the way.

When Nikon introduced autofocus in its film SLRs, it decided to retain its F mount and thus compatibility with existing lenses, as well as new AF ones, for the benefit of longtime Nikon users. Nikon’s DSLRs continued this strategy, utilizing an AF motor in the camera body to provide autofocusing with the new AF lenses. Recent (AF-S) Nikon lenses do contain focusing motors (and are required for autofocusing with entry-level Nikon DSLRs, which don’t have in-body AF motors).

Nikon was the first to offer video in a DSLR with the D90, and the newest models have improved on that, with the D7000 and D3100 even providing full-time autofocusing during video shooting.

All current Nikon DSLRs feature built-in sensor-dust removers, plus Active D-Lighting, which provides better detail in bright and dark areas in high-contrast scenes.

Nikon D3S

The most recent addition to Nikon’s top-tier pro DSLR lineup, the full-frame D3S is also the high-ISO champ, generally acknowledged to produce the best image quality of any DSLR at higher ISO settings (which go up to 102,400). The camera is extremely fast, able to shoot its 12.1-megapixel images at 9 per second in bursts of up to 36 14-bit RAW or 82 large JPEGs. It also can capture smaller DX-format images at an even faster 11 fps.

As an all-out pro camera, the D3S features rugged magnesium-alloy construction with effective protection from moisture, dust and electromagnetic interference, and its self-diagnostic shutter is tested to 300,000 cycles. The viewfinder shows 100% of the actual image area. There are two slots for CompactFlash (UDMA-compatible) memory cards. The 4-mode, 51-zone AF system is excellent with action subjects, and the 1005-pixel 3D Color Matrix Metering also meets pro expectations. The battery is good for up to 4,200 shots per charge (per CIPA standards).

Nikon D700

The Nikon D700 full-frame DSLR offers the same pixel count, and AF and metering systems as the D3S—albeit with a generation-older sensor and processor—at half the price. While it lacks the D3S’s incredible high-ISO capabilities, it delivers low-noise images with an ISO range of 200-6400 (expandable to 100-25,600). Until the introduction of the D3S, the D700 and the D3 were the state of the art for high-ISO performance.

The D700 can shoot its 12.1-megapixel images at a respectable 5 fps (8 fps with the optional MB-D10 Multi-Power Pack). While not quite as bulletproof as the D3S, the D700 features rugged magnesium-alloy construction with extensive dust and moisture sealing, and a 150,000-cycle shutter. The D700 has a built-in sensor-dust remover, the only full-frame Nikon to provide that feature until the D3S. While there’s no video capture, the D700 does offer live-view operation. You can choose between quick phase-detection AF (with the live view momentarily disrupted during focusing) or contrast-based AF (slower, but with continuous live viewing).


Nikon offers an extensive array of lenses for its DSLRs. Most Nikon DSLRs also can use (with some limitations) earlier lenses designed for Nikon film cameras. Nikon DX lenses are designed specifically for the APS-C-sensor format; when a DX lens is used on a full-frame Nikon DSLR, the camera automatically switches to a cropped DX format (with reduced pixel count).

There are more than 60 lenses in the lineup, from a 14mm wide-angle and 16mm full-frame fisheye to a 600mm telephoto, including more than 20 with built-in Vibration Reduction (VR). AF-S lenses contain silent-wave AF motors and provide quicker (and quieter) autofocusing; the other lenses use the AF motor in the camera body. DX lenses range from a 10-22mm ultrawide zoom to a 55-300mm telezoom. Three manual-focus PC-E lenses provide tilt-shift capability. There are also 1.4x, 1.7x and 2.0x teleconverters.

Nikon D300S

The D300S improved on the excellent original D300 in a number of ways. It features the same pixel count (12.3 MP), but adds HD video capability, an SD card slot to accompany the D300’s CompactFlash card slot and one-button live-view to simplify operation.

Rugged magnesium-alloy construction is complemented by advanced dust and moisture countermeasures, and a shutter tested to 150,000 cycles. The eye-level pentaprism viewfinder shows 100% of the actual image area. Nikon’s proven 51-point AF and 1005-pixel 3D Color Matrix Metering provide pro performance, while EXPEED processing increases image quality and shooting speed (7 fps, up from 6 fps in the D300).

Nikon D7000

Not to be confused with the full-frame D700, Nikon’s newest DSLR has another “0” in the name and features a 16.2-megapixel APS-C sensor. It can shoot thos
e images at 6 fps.

The D7000 introduces a new 2016-pixel RGB 3D Color Matrix Metering system and a new 39-point AF system, both of which worked very well on our D7000 test camera. While not as rugged as the pro Nikons, the D7000 nevertheless features magnesium-alloy top and rear covers, good dust and weather sealing, and a shutter tested to 150,000 cycles. Nikon’s EXPEED 2 image processing and 14-bit A/D conversion enhance image quality and camera performance. Normal ISO range is 100-6400, expandable to 25,600.

Nikon D3100

This excellent entry-level model features a 14.2-megapixel CMOS sensor and EXPEED 2 processing for remarkably good still image quality and HD video with full-time autofocusing. Normal ISO range is 100-3200, expandable to 12,800. Images are saved on SD cards, including the new SDXC cards. Fast 11-point autofocusing and 3 fps shooting provide some action capability, although not what you get with higher-end Nikon DSLRs. Like other entry-level Nikon models, the D3100 autofocuses only with lenses that contain focusing motors, the AF-S and AF-I Nikkors.


Accessories for Nikon DSLRs include flash units (pro through economy-level, plus macro flash systems), battery grips, remote controls, angle finders and wireless file transmitters. The GPS-1 GPS unit slips into the camera’s hot-shoe and can geotag each image with the latitude, longitude and altitude at which it was taken.


Sony has long been a top manufacturer of compact digital cameras and launched its first DSLR, the DSLR-A100, after purchasing Konica Minolta’s photography division in 2006. The company has released 16 DSLRs since then, and today is a major force in the interchangeable-lens digital camera arena. The current line-up includes professional full-frame models, consumer DSLRs, two models with an innovative fixed pellicle mirror and Sony’s own take on the large-sensor, interchangeable-lens mirrorless camera, the NEX series.

Konica Minolta introduced sensor-shift image stabilization to the DSLR with the Maxxum 7D back in 2003, and all Sony DSLRs have offered this great feature, which provides stabilization with any lens you attach to the camera. All Sony DSLRs offer built-in sensor-dust removers, which use ultra-high-speed vibrations to remove dust from the image sensor assembly.

Sony DSLR-A850

By far the lowest-priced full-frame DSLR, the A850 offers most of the flagship A900’s features, including the same 24.6-megapixel Sony Exmor CMOS image sensor and image processing, the same rugged magnesium-alloy body with sealing against dust and moisture, and the same image quality. Basically, what the A900 gives you for the extra $700 is a viewfinder that shows 100% of the actual area (versus 98% for the A850) and a faster maximum shooting rate (5 fps versus 3 fps), making the A850 an excellent value.

The A850 was introduced before video came to the DSLR (Canon’s EOS 5D Mark II and Nikon’s D3S are the only current full-frame DSLRs to offer video capability), but a 24-megapixel, full-frame DSLR for under $2,000 is a great bargain even without video. While it lacks a true Live View mode, Instant Preview lets you see the effects of adjustments to exposure, white balance and Dynamic Range optimizer on the LCD monitor.

Sony DSLR-A580

Sony’s top APS-C DSLR features a 16.2-megapixel Sony Exmor CMOS sensor and a host of good features, including a tilting LCD monitor and—thanks to a second live-view sensor—fast phase-detection AF during live-view operation with no disruption of the live image. The camera can shoot at 3 fps in Quick AF live mode, 5 fps in optical viewfinder mode and 7 fps in Speed Priority mode with focus locked.

The A580 features Sony’s 2D and 3D Sweep Panorama (3D requires a 3D TV set for viewing), 3-shot Auto HDR, D-Range Optimizer and Multi-Frame Noise Reduction for ISOs up to 25,600.


Sony provides a good lineup of lenses for its DSLRs, including some excellent Carl Zeiss optics. In addition, all Sony DSLRs can use virtually all Konica Minolta Maxxum lenses. DT lenses were designed specifically for the APS-C sensor and can be used on the full-frame models, but will vignette.

The DT lenses range from an 11-18mm zoom to an 18-250mm zoom, including a Carl Zeiss 16-80mm zoom. The full-frame lenses (which can be used on all Sony DSLRs) range from a 16mm full-frame fisheye and a 20mm wide-angle to a 70-400mm ƒ/4-5.6 telezoom. G-series lenses are the “elite” ones in Sony’s lineup.

Sony SLT-A55

The SLT-A55 features a fixed translucent pellicle mirror, and this confers a number of benefits. First, unlike conventional moving-mirror DSLRs, there’s no mirror vibration or viewfinder blackout when you make an exposure. Second, the camera’s quick phase-detection AF system works in live-view mode, even in video mode. Third, you can shoot videos using the eye-level electronic viewfinder if you prefer, rather than only the external LCD monitor as with other video-capable DSLRs. The nonmoving mirror also speeds camera operation.

Like Sony’s conventional DSLRs, the 14.2-megapixel SLT-A55 uses Sony A-mount lenses. The camera can shoot at 6 fps (10 fps in Speed Priority mode, with focus locked). Features shared with other recent Sony DSLRs include Sweep Panorama and effective Dynamic Range Optimizer to control contrasty scenes.

Sony NEX-5

The NEX-5 and kid brother NEX-3 are Sony’s mirrorless interchangeable-lens models, featuring APS-C sensors in very compact bodies. The NEX-5 has a 14.2-megapixel Sony Exmor HD CMOS sensor in a tiny body that’s actually a bit smaller than the NEX-3 and about half the size of Sony’s smallest DSLR.

Among the NEX-5’s highlights are a tilting 3.0-inch, 921,000-dot LCD monitor with full-time live view (there’s no eye-level electronic viewfinder, nor is one available as an option
). The NEX-5 can shoot at 2.3 fps with focusing for each shot or 7 fps in Speed Priority mode, with focus and exposure locked. AF is contrast-based and can track moving subjects. Utilizing a new Sony E-series mount, the NEX cameras take new E-mount lenses. A-mount DSLR lenses also can be used via an adapter. There’s no built-in flash, but the camera comes with a detachable TTL flash unit.

Sony DSLR-A390

The A390 is a solid entry-level DSLR, and at under $500 with a kit zoom lens, it’s a good deal. It has a 14.2-megapixel CCD sensor, can use all Sony A-mount lenses (and legacy Konica Minolta Maxxum optics) and features Sony’s SteadyShot INSIDE sensor-shift image stabilization that works with all lenses. The LCD monitor tilts 135° up and 55° down for easy high- and low-angle shooting. Quick Live View uses the camera’s quick phase-detection AF during live-view operation, but with no disruption of the live image thanks to a dedicated live-view sensor. There’s no video capability, but no DSLR at this price offers video.

The light and compact A390 can shoot at 2.5 fps. The proven 40-segment honeycomb metering provides good exposures in a wide range of situations. DRO (Dynamic Range Optimizer) improves detail in contrasty scenes, while Eye-Start AF activates the AF system when you bring the camera up to your eye to speed operation.


Sony offers a number of accessories for its DSLRs, among them flash units (including a macro twin flash and a ringlight), angle finders, cases, straps, a geotagging GPS and the LA-EA1 adapter, which lets you use A-mount DSLR lenses on the NEX mirrorless cameras.


Olympus introduced the Four Thirds System (see the “Sensor Formats” sidebar) back in 2003, the first DSLR with a built-in sensor-dust remover (the E-1 in 2003) and the first DSLR with live-view and a tilting LCD monitor (the E-330 in 2006).

Today, Olympus offers the pro-oriented E-5 and mid-level E-30 DSLRs, but has replaced its entry-level DSLRs with its mirrorless Micro Four Thirds offerings, the PEN E-PL1, E-PL2 and E-P2. Inspired by the company’s famous PEN compact 35mm cameras of the 1960s, these stylish cameras feature 12.3-megapixel High-Speed Live MOS 4/3 image sensors, effective sensor-dust removers and sensor-shift image stabilization that works with all lenses. All will accept an optional electronic view-finder, and all provide multiple-exposure capability and Olympus Art Filters.

The latest model, the E-PL2, also accepts the new PENPAL PP-1 Bluetooth unit that makes it simple to send images to friends and comes with a new MCC 14-42mm kit lens that provides near-silent autofocusing for movie use.

The E-PL1 and E-PL2 have built-in flash units; all three PEN models will accept accessory flash units. Micro Four Thirds cameras use Micro Four Thirds lenses from any manufacturer, and also can use regular Four Thirds System lenses and many other lenses via adapters.


Like DSLRs, removable memory media have evolved over the years. Today’s DSLRs use one or more of three basic types: CompactFlash, SecureDigital (SD) and Memory Sticks. While the cards vary in physical size, all do the job (storing images) quite well, the newer versions being quicker and offering higher capacities. Get the type specified for your camera to avoid speed/capacity incompatibilities.

The top CompactFlash cards are the UDMA (Ultra Direct Memory Access) ones; they’re faster than previous versions, but only if your camera is UDMA-enabled. Today’s CompactFlash cards come in speeds of up to 100 megabytes per second and capacities up to 64 GB.

The top SD cards are the SDHC (SD high capacity) and SDXC (SD extra-high capacity) ones. SDXC cards are available in capacities up to 64 GB (the format has the potential to go to 2 TB) and speeds up to 35 MB/sec. Again, get what your camera’s manufacturer recommends; cameras as well as cards have speed and capacity limits.

Sony’s DSLRs use Sony Memory Stick media, which are available in capacities up to 32 GB and speeds up to 30 MB/sec. (for Memory Stick PRO-HG Duo HX).


Panasonic introduced the first mirrorless Micro Four Thirds System camera, the Lumix DMC-G1, in 2008. Today, the company offers a next-generation lineup of Micro Four Thirds models. The Lumix DMC-GH2, DMC-G2 and DMC-G10 look like mini-DSLRs, with their built-in, eye-level electronic viewfinders complementing the full-time, live-view LCD monitors. The Lumix DMC-GF2 looks like a compact digital camera, but features a Four Thirds sensor like the other Panasonic models.

The top-of-the-line GH2 features a 16.05-megapixel Live MOS image sensor, a high-res, eye-level electronic viewfinder and an articulated LCD monitor. It can shoot full-res images at 5 fps and 4-megapixel images at 40 fps. Panasonic’s contrast AF systems are known for speed, and the GH2’s Light Speed AF is the quickest contrast-based AF yet.

The super-compact GF2 features a 12.1-megapixel Four Thirds sensor, 3.2 fps shooting, similar video capabilities to the GH2 and more. It even can do 3D still images and videos with the optional Lumix G 12.5mm ƒ/12 lens.

Autofocus Systems

DSLRs use phase-detection AF for still photos in viewfinder mode, and most let you choose between phase-detection AF and contrast-detection AF in live-view and video modes.

Phase-detection AF is quick and much better suited for action subjects. But it requires the SLR mirror to be in the down (viewing) position, so it momentarily disrupts the live view during focusing. Contrast-based AF reads right off the image sensor, so it doesn’t disrupt the live image during focusing, but it’s noticeably slower than phase-detection AF and not as well suited for action photography. There are a few exceptions. Sony live-view DSLRs employ a second sensor to provide the live image and thus can employ the same quick phase-detection AF system for live-view shooting as for viewfinder shooting. Panasonic’s recent mirrorless cameras have very quick contrast-based AF, but no phase-detection AF.


Longtime 35mm SLR maker Pentax introduced its first DSLR (the *ist D) in 2003 and has since produced 14 more. The current lineup consists of the pro-oriented K-5, the mid-level K-7, and the entry-level K-r and K-x.

The 16.3-megapixel K-5 and 14.6-megapixel K-7 are dust-, moisture- and cold-resistant. The flagship K-5 can shoot up to 7 fps, features ISOs from 80-51,200, and received the highest rating of any APS-C camera in’s RAW sensor ratings. Despite its tiny (for a DSLR) 5.2×3.8×2.9-inch, 23.3-ounce dimensions, the K-5 has a 3.0-inch, 921,000-dot LCD monitor and a 100% eye-level pentaprism viewfinder.

The 12.4-megapixel K-r can shoot still images at 6 fps. Even more compact than the K-5, the K-r measures 4.9×3.8×2.7 inches and weighs 19.2 ounces, yet incorporates the same 3.0-inch, 921,000-dot LCD monitor (but has a 96% pentamirror eye-level finder).

All Pentax DSLRs can use virtually all Pentax-mount lenses, even old screw-mount and medium-format optics (via adapters). Current DA* lenses feature quiet SDM AF motors and sealing against dust and moisture to match that of the K-5 and K-7 bodies.


Electronics giant Samsung has been making compact digital cameras for quite some time and partnered with Pentax to produce a line of DSLRs. But today, Samsung’s main thrust is its NX line of APS-C-sensor, mirrorless interchangeable-lens models, featuring 14.6-megapixel, Samsung-created CMOS sensors.

The 14.6-megapixel NX10 features a mini-DSLR form factor, with a VGA (921,000-dot) eye-level electronic viewfinder and a 3.0-inch, 614,000-dot AMOLED external monitor, which is much quicker and clearer than LCD monitors. The NX10 can shoot still images at 3 fps (and reduced-res, 1.4-megapixel images at 30 fps). It measures 4.2×3.4×1.6 inches, weighs 12.3 ounces.

The NX100 features a flat, yet stylish compact-camera form factor, with the same Samsung APS-C CMOS sensor, video capabilities, NX lens mount and AMOLED monitor, but no built-in eye-level electronic viewfinder—though a clip-on one is available as an option. You can record up to 20 seconds of sound with a still image. The NX100 measures 4.7×2.8×1.4 inches, weighs 9.9 ounces.


Lensmaker Sigma also has produced 35mm SLRs and four DSLRs featuring the unique Foveon full-color image sensor (see the “Sensor Formats” sidebar). Today, Sigma offers the SD15, with the much anticipated SD1 due soon. The SD1 will have three times the pixel count of the SD15, yet is expected to sell for under $2,000.

Sigma was the first to deliver on the concept of “DSLR image quality in a compact digital camera” when it put the same Foveon sensor used in its DSLR into a compact body with a noninterchangeable 16.6mm (28mm 35mm-camera equivalent) ƒ/4 lens to create the DP1. That camera was followed by the DP2 with a fixed 24mm ƒ/2.8 lens (equivalent to 41mm on a 35mm camera).

The latest versions are the DP1x and DP2s, which add improved TRUE II image processing, improved AF performance and more efficient power management to the originals. The DP1x measures 4.5×2.3×2.0 inches, weighs just 8.8 ounces and lists for $800. The DP2s measures 4.5×2.3×2.2 inches, weighs 9.2 ounces and lists for $940. Both are straightforward, easy-to-learn cameras, carrying on the tradition of the Sigma DSLRs.

video Formats

Most newer DSLRs and all mirrorless interchangeable-lens models offer HD video capability. Some offer 1080 full HD and others offer 720 HD. The 1080 format provides videos 1920 pixels wide and 1020 lines deep. The 720 format provides videos 1280 pixels wide and 720 lines deep. Most cameras also offer SD video, which measures 640 pixels wide and 480 lines deep (fewer lines deep with some cameras). When viewing videos on an HD television or full screen on a computer, higher-resolution video generally looks sharper and clearer with less artifacts.

Some video-capable DSLRs and mirrorless cameras provide a choice of frame rates. Common ones include 30 fps, 24 fps and 60 fps. The faster the frame rate, the smoother action sequences appear. The 24 fps rate matches the frame rate of professional motion pictures, and some feel this provides a more “cinematic” look. For pro video work, you’ll want the variable frame rate capability. Note that the NTSC video standard for 24 fps is actually 23.976 fps, 30 fps is actually 29.97 fps, and 60 fps is actually 59.94 fps. Some cameras really shoot 30 fps and 60 fps; for pro work, this is less desirable than cameras that shoot 24, 30 and 60 fps at the NTSC 23.976, 29.97 and 59.94 fps rates, respectively.

You’ll also notice a “p” or “i” following the frame rate, 1080/30p, for example. The “p” means “progressive” video, which displays one full image at a time at the specified rate. The “i” means interlaced video, which displays the odd-numbered lines, then the even-numbered lines of the image. Progressive video handles motion better than interlaced, provides entire frames for freeze-frame or still-image grabs, and has fewer artifacts. Video-capable DSLRs and mirrorless interchangeable-lens cameras output progressive video.

Size comparison of the most common sensor formats. Full frame (white); APS-C
(blue); APS-H (red); and Four Thirds (green).

Sensor Formats

Full Frame. Full-frame sensors measure 36x24mm, same as a full 35mm film image frame. Full-frame sensors are the largest in the category and thus have room for more pixels of a given size, or larger pixels for a given pixel count, both of which tend to increase image quality, especially at higher ISO settings. These sensors also provide the same angle of view as 35mm film SLRs with any given lens and the same depth of field. The drawbacks? Full-frame sensors are costly and result in bulkier camera bodies.

Smaller sensors crop further into the full image produced by a given lens, resulting in a “telephoto” effect. In the early days of DSLRs, this made for problems for wide-angle shooters: a 28mm wide-angle lens on a 35mm SLR framed like a 42mm “normal” lens when used on a typical DSLR. Today, the camera and lens manufacturers produce very short-focal-length lenses designed specifically for the smaller sensors, making wide-angle shooting no problem.

APS. APS-C sensors are about the size of an Advanced Photo System C-format image, a little less than half the size of full-frame sensors. There are three basic sizes. Nikon, Pentax, Samsung, Sony and the new Sigma SD1 feature sensors measuring around 23.7×15.7mm, with a 1.5x focal-length factor. A 1.5x focal-length factor means a 100mm lens used on that camera frames like a 150mm lens on a full-frame camera.

Canon uses a size of around 22.3×14.9mm, with a 1.6x focal-length factor. A 1.6x focal-length factor means the 100mm lens frames like a 160mm lens on a full-frame camera. Canon also offers an APS-H sensor in its non-full-frame pro DSLR, currently, the EOS-1D Mark IV. It measures around 27.9×18.6mm and has a 1.3x focal-length factor.

Four Thirds. While most SLR camera manufacturers based their digital SLRs around their 35mm film SLRs, the Four Thirds System (introduced by Olympus in 2003) was built around an all-new, smaller image sensor design measuring 17.3x13mm, with a 2x focal-length factor. The recent Micro Four Thirds System is based on the same sensor size; the “Micro” refers to the smaller camera bodies made possible by eliminating the SLR’s mirror, mirror box and prism viewfinder. By designing the camera bodies and lenses specifically for the Four Thirds sensor, Olympus was able to eliminate some of the problems that can occur when adapting lenses designed for 24x36mm film frames to use with smaller digital image sensors.

Foveon. Sigma’s unique Foveon sensors, which records all three primary colors at every pixel site, are APS-C format (1.7x factor for the SD15 and previous models, 1.5x for the new SD1). While conventional DSLR image sensors record only red, green or blue at any single pixel site, acquiring the missing color data from neighboring pixels using complex proprietary algorithms, the Foveon sensors “stack” three pixel layers, taking advantage of the fact that light wavelengths penetrate silicon to different depths depending on wavelength (color)—the top layer records blue, the middle layer, green, and the bottom layer, red. Thus all three primary colors are recorded at every pixel site, no “demosaicing” (deriving the missing colors) or image-blurring, anti-aliasing filters are needed.

What Is Mirrorless?

“SLR” is short for “single-lens reflex.” The “reflex” part refers to the reflex mirror that these cameras contain. The mirror normally sits at a 45° angle, reflecting the image from the lens up to a focusing screen and then to the pentaprism (pentamirror in lower-priced cameras) where the image is switched to a laterally correct and upright orientation and sent to the viewfinder eyepiece. When you fully depress the shutter button to take a photo, the mirror flips up out of the light path so light can reach the image sensor. The mirror then automatically drops back down to the viewing position after the exposure has been made. The viewfinder image is briefly interrupted while the exposure is made—the viewfinder momentarily “blacks out.”

Mirrorless interchangeable-lens cameras, as their name suggests, don’t have this mirror. Instead, they rely on full-time live viewing with their large external LCD monitors to provide the image used for composing shots and confirming focus. Doing away with the SLR’s moving mirror, bulky mirror box, focusing screen and pentaprism or pentamirror viewfinder allows manufacturers to produce much smaller camera bodies (and eliminates the cost of these items).

Some mirrorless cameras also have an eye-level electronic viewfinder, which allows them to be used like SLRs, held up to the eye. Electronic viewfinders aren’t as clear as true SLR finders, especially for action subjects and in dim light, but they provide convenient eye-level viewing, are much more compact and cost less. With some such cameras, the electronic viewfinder is built-in (the Panasonic Lumix DMC-GH2, DMC-G2 and DMC-G10 and the Samsung NX10, for example); these models resemble very compact DSLRs. Some other mirrorless models offer a clip-on EVF as an accessory, while others don’t offer an electronic viewfinder. If eye-level viewing is important to you, make sure the camera you choose has one.

Sony’s new SLT cameras (the SLT-A55 and SLT-A33) feature an SLR design, but use a translucent mirror that doesn’t move. This permits quick phase-detection AF during live view and video operation, and does away with mirror vibration and viewfinder blackout during exposure. Pellicle mirrors tend to produce dim SLR viewfinder images, so Sony uses eye-level electronic viewfinders in the SLT cameras. These cameras provide convenient eye-level operation when shooting videos—a nice feature.

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