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Compact DSLRS
Ever since the tiny Olympus OM-1 35mm film SLR was introduced in the early 1970s (and perhaps even before), there's been a desire among many for smaller and lighter interchangeable-lens cameras. Especially for outdoor photographers, who often must cart gear deep into rugged terrain, the benefit of smaller and lighter camera bodies and camera systems has beckoned strongly.
Today, we have a wide range of very compact digital SLRs in several formats. For those for whom size trumps all, a lot of mirrorless interchangeable-lens cameras are even smaller (though not as well suited to some types of outdoor shooting). Here's a look at what's available to the size-conscious outdoor photographer in today's DSLR market.
Full-Frame
Full-frame DSLRs can deliver excellent image quality because their large image sensors can collect more photons and more photons means a higher signal-to-noise ratio. And despite their big sensors, the three compact full-frame DSLRs we're looking at in this article really are compact, about the size of a high-end APS-C model and a bit lighter. This makes them great choices for the outdoor photographer who's after the ultimate image quality in an easy-to-carry package. Their main drawback for outdoor work is for wildlife photography. Full-frame sensors provide a wider angle of view with any given focal length than smaller sensors. The subject will appear bigger in the frame on an APS-C camera and a full-frame one when the same lens is used, and a 24-megapixel APS-C DSLR gives you more "reach" than a 24-megapixel full-frame camera.
Canon's most compact full-frame camera is the EOS 6D, featuring a 20.2-megapixel sensor in a body that measures just 5.7x4.4x2.8 inches and weighs just 24 ounces. It can use all Canon EF and TS-E lenses, but not the EF-S or EF-M optics designed especially for APS-C sensors. EF focal lengths range from a 14mm superwide-angle to an 800mm supertelephoto, plus an 8-15mm fisheye zoom and manual-focus tilt-shift TS-E lenses of 17mm, 24mm, 45mm and 90mm. There are also 1.4X and 2.0X teleconverters, and several true macro lenses, including a 1-5x optic. The EOS 6D's big pentaprism viewfinder shows 97% of the actual image area, while the 3.0-inch, 1040K-dot LCD monitor provides easy live viewing. The camera can shoot full-res images at up to 4.5 fps, and has a normal ISO range of 100-25,600, expandable to 50-102,400. Images are saved on SD, SDHC or SDXC media (UHS-I-compatible). The 6D features enhanced dust and weather resistance, and has built-in WiFi and GPS. It also offers good video capabilities, including 1920x1080 at 30p and 24p and 1280x720 at 60p. Focusing during video shooting is done manually.
Nikon's most compact full-frame DSLR is the D600, which provides a 24.3mm sensor in a body measuring 5.6x4.4x3.2 inches and weighing 26.8 ounces. It can use all AF Nikkor lenses, including DX ones designed for APS-C sensors (the camera will automatically crop to DX format when a DX lens is attached). Available FX (full-frame) focal lengths run from 14mm to 800mm, including a 16mm full-frame fisheye, several 1:1 macro lenses and three manual-focus tilt-shift PC-E lenses (24mm, 45mm and 85mm), as well as 1.4X, 1.7X and 2.0X teleconverters. The D800 can shoot full-res images at up to 5.5 fps, and has a normal ISO range of 100-6400, expandable to 50-25,600. A big pentaprism viewfinder shows 100% of the actual image area, and is complemented by a 3.2-inch, 921K-dot LCD monitor. WiFi and GPS are available via optional accessories. Dual memory-card slots accept SD/SDHC/SDXC media, with UHS-I compliance. The D600 features extensive weather sealing, providing dust and moisture protection equivalent to that of the D800/D800E cameras. Video capabilities include 1920x1080 at 30p and 24p and 1280x720 at 60p. Contrast-based AF is available during video, but is fairly slow.
Sony's only full-frame DSLR, the Alpha SLT-A99 features a 24.3-megapixel sensor and it measures 5.8x4.4x3.1 inches and weighs 25.9 ounces. The A99 can use all Sony A-mount and legacy Konica Minolta lenses; when a DT (APS-C) lens is attached, the camera automatically crops to APS-C format. Full-frame lenses range from a 16-35mm superwide zoom and a 16mm full-frame fisheye to a 500mm supertelephoto, including 1:1 macro and 1.4X and 2X teleconverters.
The A99 features Sony's Translucent Mirror Technology (TMT), with a fixed semitranslucent mirror rather than the moving mirror found in conventional DSLRs. The TMT mirror transmits most of the light to the image sensor, while directing a portion up to the phase-detection AF sensor. This enables the Sony SLT cameras to provide constant phase-detection AF during live view and video shooting. The nonmoving mirror also does away with SLR mirror vibration, which is important for landscape work at longer shutter speeds. SteadyShot INSIDE sensor-shift image stabilization works with any lens. The A99 can shoot full-res images at 6 fps with continuous AF and 10-megapixel APS-C images at 7 fps (8-10 fps in Tele Zoom Continuous Advance Priority mode). Normal ISO range is 100-12,800, expandable to 50-25,600. With the TMT system, the A99 has an OLED Tru-Finder instead of a typical DSLR optical viewfinder—the same unit used in the SLT-A77, that permits eye-level viewing for video as well as still shooting. The 3.0-inch, 1229K-dot LCD monitor tilts in almost any direction for easy odd-angle shooting. The body is sealed against dust and moisture, and the shutter is rated at 200,000 cycles. Slots are provided for SD/SDHC/SDXC cards and Sony Memory Stick PRO/PRO-HG Duo media. Video capabilities include 1920x1080 at 60p and 24p, with full-time phase-detection AF (or manual focus, if you prefer) and eye-level viewing.
Mirrorless interchangeable-lens cameras have become popular over the past few years, largely owing to their combination of DSLR image quality and truly small size. Most feature APS-C or Four Thirds sensors, and many will—with "pancake" lens attached—fit in a jacket pocket. The mirrorless cameras get their small size—and class name—from the fact that they do away with the DSLR's bulky and complex SLR mirror box and pentaprism (or pentamirror) viewfinder, replacing them with an eye-level electronic viewfinder (EVF) or just using the external LCD monitor for composition. The shortened distance from lens mount to image plane also allows for less bulky lenses (considerably less bulky for Micro Four Thirds cameras, and somewhat less bulky for APS-C models).
The big benefit of the mirrorless cameras is the ease of carrying them around. If you just want to have a camera with you—one capable of delivering DSLR image quality—at all times, it's much easier to take a mirrorless camera with a zoom lens or two than to lug a big DSLR and an equivalent lens. Mirrorless models make great hiking cameras, especially when covering terrain that requires use of your hands as well as feet. Some serious outdoor shooters find themselves taking their mirrorless cameras along more often than their DSLRs.
The main drawbacks to mirrorless cameras are lack of an "always-on" optical viewfinder and relatively short battery life. Some mirrorless cameras have eye-level electronic viewfinders (either built in or available as clip-on accessories), but even though EVFs have improved a lot of late, they still aren't nearly as good as a DSLR finder for tracking action subjects like birds in flight. Mirrorless cameras are in Live View mode all the time, so they go through batteries more quickly than DSLRs, and since they generally have smaller batteries to keep camera size down, this can be a problem. Also, there are fewer lens choices available for mirrorless cameras than for most DSLRs.
Bottom line: If you shoot a lot of wildlife or sports action, a DSLR is a better choice, otherwise a mirrorless camera is certainly worth considering if minimizing camera size is important.
APS-C
The APS-C format includes the smallest current DSLRs, thanks in large part to image sensors less than half the size of full-frame (36x24mm) sensors. The resulting 1.5X "crop factor" (1.6X for Canon) is good for long-lens users like wildlife photographers, and less so for wide-angle landscape fans, as any focal length used on an APS-C camera frames like a lens 1.5X or 1.6X the focal length on a full-frame camera. However, between the camera manufacturers and independent lens makers such as Sigma, Tamron and Tokina, very wide-angle lenses designed specifically for the format are available for APS-C DSLRs, so landscapes don't present the problems they did in the early days of the DSLR, when there were few full-frame DSLRs and no APS-C lenses.
Canon's new 18.0-megapixel EOS Rebel SL1 is the smallest DSLR as of this writing (late April 2013), measuring just 4.6x3.6x2.7 inches and weighing a mere 13.1 ounces. But it features a 3.0-inch, 1040K-dot touch-screen LCD monitor and takes the full range of Canon EF (full-frame) and EF-S (APS-C) lenses. These range from an 8-15mm fisheye zoom and a 10-22mm superwide zoom to an 800mm supertelephoto, providing 35mm-camera-equivalent focal lengths of 16-1280mm (12mm, including the fisheye zoom). These, plus four TS-E tilt-shift lenses and true macro lenses, can handle pretty much any outdoor shooting need. The Rebel SL1 can shoot full-resolution images at 4 fps, provides a normal ISO range of 100-12,800 and in-camera HDR, and stores images on SD/SDHC/SDXC media (UHS-I included). It also can shoot 1920x1080 full HD video at 30p and 24p or 1280x720 HD at 60p, with Movie Servo contrast-based AF during shooting. Canon also offers other larger, but still very compact EOS Rebel models, the top one being the T5i. It has the SL1's features, but the LCD monitor tilts and rotates, normal ISO range is 100-12,800, it can shoot at 5 fps, and all nine AF points are cross-types. The T5i measures 5.2x3.9x3.1 inches and weighs 18.5 ounces.
Nikon offers several compact DSLRs, the smallest (by a small margin) being the 14.2-megapixel D3100 entry-level camera. Landscape shooters will likely prefer the marginally larger 24.2-megapixel D3200 or 24.1-megapixel D5200, which deliver noticeably better image quality, especially for larger print sizes. (The D3100 scored 67 in DxOMark.com's raw sensor ratings, compared to 81 for the D3200 and 84 for the D5200. The D3100 measures 4.9x3.8x2.9 inches and weighs 16 ounces; the D3200, 5.0x3.8x3.1 inches and 16 ounces; and the D5200, 5.1x3.9x3.1 inches and 17.8 ounces. All feature pentamirror viewfinders that show 95% of the actual image area and 3.0-inch LCD monitors (230K dot for the D3100, 921K dot for the D3200 and D5200, plus the D5200's monitor tilts and rotates). The D5200 has better AF and metering systems (39-point AF and 2016-pixel metering vs. 11-point AF and 420-pixel metering), and can shoot faster (5 fps vs. 4 fps for the D3200 and 3 fps for the D3100). The D5200 also offers in-camera HDR. All can accept a wide range of AF Nikkor lenses, but none has an in-body AF motor, so they will autofocus only with lenses that have one: AF-S. AF-S lenses range from a 10-22mm superwide zoom to an 800mm supertelephoto, though equivalent to 15mm through 1200mm on a full-frame DSLR, so all three cameras can handle pretty much any outdoor shooting situation. Normal ISO range is 100-3200 for the D3100 and 100-6400 for the others. All can shoot 1920x1080p full HD video at 24 fps; the D3200 also can do it at 30p and the D5200 at 30p and 60i.
Some of the mirrorless interchangeable-lens cameras have a "flat" form factor like typical compact point-and-shoot digital cameras (albeit with more advanced capabilities), while others look like mini-DSLRs. While some of the former will accept optional clip-on eye-level electronic viewfinders, the latter have eye-level EVFs built in, and can be held and used much like regular DSLRs. This provides a more familiar feel for photographers used to DSLRs (or coming from film SLRs), and provides steadier handholding than the arm's-length hold required when using the external LCD monitor to compose and shoot. (All of the "mini-DSLR"-style mirrorless models have external LCD monitors, too, some with tilting/rotating capabilities.) Of course, the "mini-DSLR"-style cameras are less pocketable than the "flat" ones. Current "mini-DSLR"-style mirrorless models include the Olympus OM-D E-M5, Panasonic Lumix DMC-GH3 and G6, and Samsung NX20.
The smallest Pentax DSLR is the K-30, at 5.1x3.8x2.8 inches and 20.8 ounces. The higher-end K-5 II and K-5 IIs models (the latter with no anti-aliasing filter over the sensor and thus capable of the greatest resolution) are marginally larger at 5.2x3.8x2.9 inches and 23.3 ounces. All feature excellent 16.3-megapixel image sensors (the 12-bit K-30 scoring 79 at DxOMark.com, the 14-bit K-5 models, 82), and all feature rugged weatherproof/coldproof bodies. Current lenses range from a 14mm superwide to a 560mm supertele (equivalent to 21mm through 840mm on a full-frame DSLR), including macro lenses. (DA* and WR lenses are weatherproof, like the camera bodies.) Pentax DSLRs also can use all K-mount Pentax lenses and, via adapters, even medium-format and old screw-mount Pentax lenses. Other features of note to outdoor photographers include in-camera HDR, pentaprism finders that show 100% of the actual image area, 3.0-inch, 921K-dot LCD monitors (with live-view focus peaking) and quick shooting (6 fps for the K-30, 7 fps for the K-5 models). You also can shoot 1920x1080 full HD video at 30 fps or 1280x720 HD at 60p.
Sigma's smallest DSLR is the SD15 at 5.7x4.2x3.2 inches and 24 ounces, but the much newer SD1 Merrill measures only marginally larger at 5.7x4.4x3.1 inches and 24.7 ounces, yet provides 3X the pixel count, much better image quality and better weather resistance, and is an all-around better choice for outdoor photography, landscapes and wildlife. The key feature of the SD1, of course, is the unique Foveon image sensor, which records all three primary colors at every pixel site. Conventional sensors used in other DSLRs record only one primary color at each pixel site, producing the missing colors by interpolation via complex proprietary algorithms via a process known as demosaicing. This process produces moiré and artifacts, which are dealt with by using an anti-aliasing filter over the sensor. This slightly blurs the image at the pixel level, reducing sharpness. The Foveon sensor requires no demosaicing, and thus no anti-aliasing blurring filter, so image detail is much better than with a conventional sensor of equivalent horizontal-by-vertical pixel count.
Sony's smallest current DSLR is the 20.1-megapixel Alpha SLT-A58, at 5.2x3.8x3.1 inches and 17.3 ounces. Like all Sony SLT models, it features the company's TMT (Translucent Mirror Technology), with a nonmoving, semitranslucent mirror that transmits most of the light to the image sensor, while simultaneously sending a portion to the phase-detection AF sensor. Thus, you get full-time phase-detection AF, even for video shooting, and there's no mirror vibration to blur long-exposure landscapes. An eye-level OLED electronic viewfinder replaces the conventional DSLR's optical finder, so you can shoot video with the camera at your eye—much more convenient and stable than holding it at arm's length and using the rear LCD monitor (that tilts, for convenient high- and low-angle shooting). Of special interest to outdoor shooters are in-camera HDR, easy Sweep Panorama, Multi-shot NR, Handheld Twilight mode and SteadyShot INSIDE sensor-shift image stabilization that works with all lenses. Sony A-mount lenses range from an 11-18mm superwide zoom to a 500mm supertelephoto, providing focal lengths equivalent to 16.5-750mm on a full-frame camera. (Sony DSLRs also can use legacy Konica Minolta lenses.) Normal ISO range is 100-16,000. The A58 can shoot 1820x1080 full HD video at 60i and 24p. If you want more pixels for big landscape prints or faster shooting (10 fps with continuous AF vs. 5 fps for the A58), the 24.3-megapixel SLT-A65 is only a bit bigger at 5.2x3.8x3.2 inches and 19.1 ounces, and also offers a larger 3.0-inch, 921K-dot monitor that rotates, as well as tilts.
Olympus' pro-oriented E-5 is the only current Four Thirds System DSLR, and thus the most compact. It's actually about the same size as the compact full-frame DSLRs described in this article, but the smaller 17.3x13.0mm Four Thirds image sensor means lenses can be much smaller for a given field of view: A 300mm lens on the E-5 frames like a 600mm on a full-frame DSLR, but is much smaller than a 600mm. The 12.3-megapixel E-5 features a rugged splash- and dustproof body, a tilting/swiveling 3.0-inch, 920K-dot LCD monitor, a normal ISO range of 100-6400 and 5 fps shooting. It also can shoot 1280x720 HD and 640x480 SD video at 30p. Current lenses range from a 7-14mm superwide zoom (equivalent to 14-28mm on a full-frame DSLR) and an 8mm fisheye to the aforementioned 300mm (600mm equivalent) supertelephoto, plus 1.4X and 2.0X teleconverters.