All About Mirrorless

There’s no question that mirrorless, interchangeable-lens cameras are increasingly popular—more mirrorless models were introduced last year than traditional DSLRs. Their main advantages are size and weight. By eliminating the mirror and pentaprism or pentamirror viewfinder, the camera itself and the system’s lenses can be made considerably smaller and lighter. For many photographers, these advantages outweigh the drawbacks of slower contrast-detection AF and the lack of an optical viewfinder.

The first mirrorless camera models from Panasonic and Olympus, dubbed Micro Four Thirds, featured standard 17.3×13.0mm Four Thirds sensors, the same sensors as those used in Olympus’ larger DSLRs (the "Micro" refers to the body design, not the sensor). Current mirrorless models from these manufacturers continue that trend.

Samsung and Sony soon followed with mirrorless models based around larger APS-C sensors (about 23.5×15.6mm), the same size used in their DSLRs. Despite the larger sensors, the Samsung NX and Sony NEX mirrorless bodies are about the same size as the Micro Four Thirds cameras. Because the sensors are larger, however, the APS-C cameras require larger-diameter lenses. This makes the camera and lens package a bit larger than the Micro Four Thirds models, but nowhere near the size of even an entry-level DSLR package.

In 2011, Pentax introduced the smallest mirrorless, interchangeable-lens camera of all. The Q’s diminutive form is possible because it’s built around a compact-camera-size, 6.2×4.6mm sensor. The tiny sensor means the lenses also can be tiny: The 100mm telephoto lens (35mm equivalent) measures just 1.6×0.8 inches and weighs less than an ounce!

Most recently, Nikon joined the party with its Nikon 1 system, introducing the J1 and V1 mirrorless cameras, featuring a CX-format sensor which, at 13.2×8.8mm, is about midway in size between a typical "compact" camera sensor and Micro Four Thirds.

As you’d expect, the cameras with larger sensors deliver better image quality, but all the mirrorless models produce better image quality than typical compact digital cameras.


Because mirrorless-camera sensors are smaller than "full-frame," 35mm-sized sensors, they effectively crop into the image formed by the lens, producing a telephoto effect compared to the same lens used on a full-frame DSLR.

APS-C sensors have a 1.5x focal-length factor (approximately); Micro Four Thirds System sensors have a 2.0x factor; Nikon’s CX sensor has a 2.7x factor; and the Pentax Q sensor has a 5.5x factor. This means a 28mm lens used on an APS-C camera frames like a 42mm lens on a 35mm camera. When used on a Micro Four Thirds camera, a 28mm lens frames like a 56mm lens on a 35mm camera. When used on the Nikon J1 or V1, a 28mm lens frames like a 76mm, and when used on the Pentax Q camera, a 28mm lens frames like a 154mm. The primary significance of all this is that it’s tough to get really wide-angle lenses for smaller-sensor cameras. Comparing the lenses currently available today for mirrorless systems, the widest you’re going to go is a 24-27mm equivalent, the exception being with Micro Four Thirds cameras, thanks to Panasonic’s 7-14mm, which frames like a 14-28mm.

Of course, if you’re a telephoto fan, the smaller sensors are a good thing, with equivalent focal lengths up to 600mm available today. See the chart to get an idea of the range of focal lengths available for each mirrorless systems.

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Since mirrorless cameras are much thinner front to back than DSLRs, they have a smaller "flange back distance," the distance from the lens mount to the image sensor. That means a wide variety of lenses for other cameras can be used with them via adapters.

Olympus and Panasonic offer adapters that let you mount standard Four Thirds System lenses on Micro Four Thirds mirrorless cameras, in most cases retaining all camera features. Panasonic offers adapters to mount Leica M and R lenses on MFT cameras, and Olympus has an adapter to use Olympus OM SLR lenses.

Sony offers two adapters that let you use Sony (and legacy Konica Minolta Maxxum) SLR lenses on the NEX mirrorless cameras. The new LA-EA2 adapter even incorporates a phase-detection AF system similar to the one in Sony’s SLT-A65 translucent-mirror DSLR, providing quick, continuous autofocusing with these lenses.

Nikon’s FT1 Mount Adapter lets you use Nikon DSLR lenses on the J1 and V1, providing autofocusing with those that contain AF motors (the AF-S lenses). Samsung’s Pentax adapter lets you use Pentax SLR lenses with the NX camera. As yet, Pentax doesn’t provide any adapters for the Q camera.

Independent companies such as Novoflex, Pro Optic and Redrock Micro produce adapters to attach a wide range of lenses to mirrorless cameras (mainly, Micro Four Thirds and Sony NEX). While the adapters provided by the mirrorless camera makers generally support all camera features, the third-party adapters often just let you attach the lens; there may be no autofocusing, and exposure controls may be limited to manual or aperture-priority. Be sure to check out the capabilities of the adapters for your system if you’re looking to use lenses not specifically designed for your camera.


Nikon. Nikon is the most recent manufacturer to enter the mirrorless market, with the J1 and V1 models. Each has a 10-megapixel, CX-format sensor and a new hybrid phase-detection/contrast-detect AF system that features phase-detection sensors right on the image sensor for faster autofocusing.

Major differences between the V1 and the J1 are that the former has a built-in, eye-level electronic viewfinder and a 3.0-inch, 921K-dot LCD monitor, while the J1 has a 460K-dot LCD and a flash in place of the eye-level EVF.

Four lenses were introduced with the cameras—three zooms with built-in Vibration Reduction (VR 10-30mm ƒ/3.5-5.6, VR 30-100mm ƒ/3.8-5.6 and VR 10-100mm ƒ/4.5-5.6 PD Zoom), plus a 10mm ƒ/2.8. System accessories include a wireless remote control, a geotagging GS unit, a stereo microphone and the SB-N5 flash unit for the V1.

Olympus was one of the first to debut a mirrorless camera, based on the Four Thirds sensor developed jointly with Panasonic. The Olympus PEN camera line’s newest models join a robust system offering that includes 10 dedicated lenses and a variety of accessories.

Olympus. Olympus has produced seven PEN mirrorless, interchangeable-lens cameras, beginning with the E-P1, all featuring a "flat," compact-digital-camera-type design. There are three lines in the PEN family—the E-P, E-PL and E-PM—and the most recent models are the E-P3, E-PL3 and E-PM1.

The E-P3 is the top model, with a 3.0-inch, 614K-dot OLED touch-screen monitor—just touch the point in the image where
you want the camera to focus, and it will quickly focus there and immediately make the shot. Besides 12.3-megapixel still images, the E-P3 can shoot 1920×1080 full HD video at 60i and 1280×720 at 60p, both in AVCHD format, plus 1280×720 at 30p and 640×480 at 30p in AVI Motion JPEG format, with CD-quality stereo sound.

The E-PL3 offers similar features and a tilting (but not touch-screen) LCD monitor in a smaller, lower-priced package. The E-PM1 is the smallest and lightest PEN model, with the same sensor and video capabilities as the other two new models, but with a fixed LED monitor.

Olympus currently offers 10 lenses for the PEN cameras, including a flat 17mm ƒ/2.8 "pancake" lens, which is so small that you can easily fit the camera in a coat pocket with the lens attached. There are also fisheye, wide-angle and macro lens converters, and because they’re Micro Four Thirds cameras, the PEN models also can use all MFT lenses, including the 14 offered by Panasonic.

Accessories include the MAL-1 Close-up Spotlight/Macro Arm Light, optional electronic viewfinders and flash units, and even underwater housings for the E-PL1 and E-PL2.

Panasonic’s Lumix G mirrorless system boasts the largest selection of lenses developed specifically for the Micro Four Thirds format, with 14 lenses covering focal lengths from a very wide 14mm to a 600mm supertele (35mm equivalent).

Panasonic.Panasonic has delivered 10 mirrorless models, beginning with the Lumix DMC-G1 in 2008. Panasonic has four mirrorless lines: G, GF, GH and GX. The most recent models are the G3, GF3, GH2 and GX1.

The new Lumix DMC-GX1 is the top "flat" model from Panasonic, featuring a very compact body, touch-screen operation and a 16-megapixel sensor with new noise-reduction technology.

The 12.3-megapixel GF3 is the smallest member of Panasonic’s G family, with a "flat" design, and actually will fit into a pocket with one of the smaller lenses attached. It offers fast performance and simple operation, including touch-screen AF for still and video shooting.

Panasonic currently offers 14 lenses for its mirrorless cameras, including several with power zooming and near-silent motors designed for video use (but also great for stills). More than half of the lenses have built-in optical stabilizers. The 8mm ƒ/3.5 full-frame fisheye is unique among mirrorless systems.

Accessories include three flash units, a remote shutter, an AC adapter, filters, cases, bags, straps and SD cards. Video accessories include the DMW-MS1 Stereo Microphone and DMW-ZL1 Zoom Lever.

Introduced in 2011, the Pentax Q is the smallest of the mirrorless models available today, made possible by a very small sensor. There are also five new lenses for the Pentax Q, designed to capitalize on the camera’s diminutive form, as well as an optional optical viewfinder.

Pentax. Pentax’s first (and thus far only) mirrorless model is the tiny Q, by far the smallest mirrorless camera, thanks in large part to its 6.2×4.6mm, 12.4-megapixel backlit CMOS sensor. Nonetheless, it manages to fit in a big 3.0-inch, 460K-dot LCD monitor on the back, a pop-up flash and lots of features.

The body features durable, scratch-resistant magnesium-alloy covers. The camera can shoot 12-bit DNG RAW, as well as JPEG still images and 1920×1080 HD video at 30p. Sensor-shift shake reduction provides stabilization with all lenses.

Pentax offers five lenses for the Q. Each lens contains a shutter, with speeds from 30 to 1?2000 sec., and flash sync at all speeds; there’s also an electronic shutter that goes to 1?8000 sec. There are currently no lens adapters for the Q.

The optional accessory Viewfinder O-VF1 provides eye-level viewing (it’s a glass optical device, not electronic).

The Samsung NX series features a large, APS-C-format sensor and eight lenses, ranging from 27mm on the wide end to 305mm on the telephoto end (35mm equivalent). Samsung also offers an adapter to allow use of Pentax K-mount lenses.

Samsung. Samsung has produced a number of NX-series mirrorless models, three of which are available in the U.S. The original NX10 features a "mini-DSLR" form factor, with a built-in eye-level electronic viewfinder, 14.6-megapixel sensor and 3.0-inch, 614K-dot AMOLED monitor, and can record 1280×720 HD video at 30p with mono sound. The NX100 provides similar features in a more compact "flat" form factor. The new NX200 features a 20.3-megapixel sensor, 1920×1080 full HD video with stereo sound and full-res still-image shooting at 7 fps.

Currently, Samsung offers three lenses for the NX cameras: the 18-55mm ƒ/3.5-5.6 portrait lens, ultracompact 20-50mm ƒ/3.5-5.6 zoom and 30mm ƒ/2 pancake lens. More lenses are in the works, and adapters allow use of a wide variety of third-party lenses. Samsung offers an adapter that permits use of Pentax K-mount lenses.

Samsung accessories include a GPS unit and two flash units.

Sony’s NEX camera system includes nine dedicated E-mount lenses, plus adapters that allow use of Sony’s A-mount lenses, like the LA-EA2 adapter, which adds Phase Detection AF capabilities. There are also a variety of accessories available, including a stereo microphone and a portable five-inch monitor—ideal for video—that incorporates a headphone jack for audio monitoring.

Sony. Sony’s two original NEX models, the NEX-3 and NEX-5, have been replaced by three: the NEX-C3, NEX-5N and NEX-7. The flagship NEX-7 features the same 24.3-megapixel, APS-C sensor as Sony’s SLT-A77 DSLR and a built-in eye-level OLED Tru-Finder to complement the tilting 3.0-inch, 921K-dot LCD monitor. Video function incorporates the new AVCHD Progressive 2.0 format, delivering 1920×1080 full HD video at 60p, as well as 60i, plus 1080/24p video and MP4 video when smaller files are desired, all with stereo sound via a built-in microphone. The camera can shoot full-res images at 10 fps with focus locked (2.5 fps with autofocusing).

The NEX-5N is even tinier than the original NEX-5 and improves on it with a 16.1-megapixel Sony sensor, quicker operation and a tilting 3.0-inch, touch-screen LCD. There’s no built-in eye-level electronic viewfinder, but one with the same OLED technology as the NEX-7’s is available as an accessory. Video capabilities are similar to the NEX-7’s.

The NEX-C3 is the smallest and simplest-to-use NEX, with a new 16.2-megapixel Sony sensor and 1280×720 at 30p video in MP4 format.

Sony’s current E-mount lens lineup for the NEX cameras includes nine lenses. Sony also offers two adapters that permit use of Sony A-mount DSLR lenses (and legacy Konica Minolta Maxxum lenses), and the aforementioned LA-EA2 adapter with its own translucent-mirror phase-detection AF system built-in.

Sony accessories include a compact stereo microphone, optical and OLED eye-level viewfinders, remote controls and flash.

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