Mirrorless camera

MILCs feature a large sensor in a small body (full-frame Leica M9 rangefinder camera)

A mirrorless interchangeable lens camera (MILC, commonly referred to simply as a "mirrorless camera"), is a camera with an interchangeable lens that does not have a mirror reflex optical viewfinder. They are a subset of interchangeable lens cameras, a category that also includes single-lens reflex cameras (SLRs or DSLRs for digital models).

These are also referred to as Interchangeable Lens Cameras (ILC) or Compact System Cameras (CSC). These cameras don’t have an optical viewfinder and usually come with an electronic viewfinder (EVF)

Mirrorless cameras are designed to have the advantage of smaller size, lighter weight, lower end models with lower cost than SLRs, and frame using what the sensor sees rather than using optical views, with exchangeable lenses.

Mirrorless cameras only constituted five percent of total camera shipments in 2013. In 2015, mirrorless-cameras accounted for 26 percent of interchangeable-lens camera sales outside the Americas, although lesser share of 16 percent in the U.S., but still a huge increase in interchangeable lens camera market share in only two years.

Mirrorless cameras are available with a variety of sensor sizes including 1/2.3", 1/1.7", 1", Micro 4/3, APS-C, and full frame. When sales of DSLRs fell in 2013, many camera manufacturers, including Nikon, responded by releasing many mirrorless cameras including the lenses.

As of 2014, several mirrorless camera systems were available. In chronological order (by their introduction) and referring to the adopted lens-mount type, they are: Epson R-D1 using Leica M mount in 2004; Leica itself in 2006; Micro Four Thirds mount for Olympus and Panasonic; Samsung NX-mount; Sony E-mount; Nikon 1-mount; Pentax Q mount for Pentax small-sensor Mirrorless (Pentax Q); K-mount for both Pentax DSLRs and Pentax large-sensor mirrorless; Fujifilm X-mount; and Canon EF-M mount. (Sony's full-frame Mirrorless, introduced in late 2013, use the same E-mount as the company's APS-C mirrorless, but attain full-frame coverage with "FE" lenses.)

Types of digital cameras

Mirrorless Panasonic Lumix DMC-GF1 (left side), and the compact digital camera on the right side is Canon PowerShot G11

Several types of digital cameras are available on the market, including:

• DSLR ILC cameras, which have an optical viewfinder for viewing the image through the lens and usually have a relatively large sensor. The mirror moves out of the way for exposure allowing the light to hit the sensor.
• Compact cameras, which are usually equipped with small sensors, a fixed lens, and an electronic viewfinder (e.g., a rear-facing LCD display). Smaller sensor may have relatively poor imaging in some situations such as low light, as it is unable to capture as much light as a larger sensor.
• The fixed mirror Sony SLT camera, which uses a semi-transparent mirror mounted in a fixed position and has a relatively large sensor and an electronic viewfinder. The mirror is used for continuous phase-contrast auto-focusing for still and motion pictures.

Mirrorless types

Sony NEX-5

Mirrorless cameras feature lens interchangeability. The size of sensors in mirrorless cameras varies more than with ILC "DSLR" cameras.

Three styles of mirrorless exist: Compact, "Rangefinder" style which can have slim electronic in built viewfinders, and DSLR style which while thinner than DSLRs their electronic viewfinders are located in humps that resemble the DSLR form factor. Compact-style cameras are approximately the size of larger compact cameras, "Rangefinder" varies a lot in size depending on sensor size while DSLR-style mirrorless cameras overlap with entry-level DSLRs in styling with significantly thinner and lighter bodies. "IBIS" sensor stability systems which stabilise lens via a sensor that floats in a magnetic field have also have increased the depth or thickness and weight of mirrorless cameras. No DSLR has IBIS stability technology.

Not all mirrorless cameras have a large sensor: The original Pentax Q (announced in June 2011) has a 1/2.3" sensor (typical of mainstream compact cameras); the current Pentax Q7 (announced in June 2013) has a 1/1.7" sensor (typical for high-end compacts). In September 2011 a new sensor format was announced by Nikon for its first mirrorless: the CX format, with a sensor area 2.6 times bigger than the 1/1.7" sensor equipping high-end compact cameras, and about half the size of a Four Thirds sensor. The Sony NEX looks like a compact camera with a zoom lens, but has a larger sensor; its APS-C sensor is the same size as that of most (amateur) DSLRs. The Canon EOS M, that company's first Mirrorless, currently the body is larger than the Sony NEX series, has a Canon APS-C 22.3 x 14.9 mm sensor - a 1.6 times crop factor - which is smaller than the Sony Nex sensor's 23.5 x 15.6 mm 1.5 times crop factor, but is larger than Micro Four Thirds sensors' 17.3 x 13 mm, 2 times crop factor.

In 2013, Sony announced a transition away from the NEX brand name, with future cameras in that family to be called Alpha ILCE; six mirrorless in the renamed family, the Alpha 7, 7R, 7S, 7-II, 7R-II and 7S-II are full-frame.

3D mirrorless

Using a prime lens – described as a 45mm f/1.8 2D/3D lens – the Samsung NX300 can take 2D stills, 3D stills or Full HD movies (see Stereo camera#Use of one camera and one lens). Micro for thirds has had 3D lenses available from their introduction.

Waterproof mirrorless

In September 2013, Nikon launched the AW1, the world's first waterproof mirrorless with capability of 15 meters underwater, 1" sensor size, 14.2MP, Full HD video, 15 fps continuous AF or 60 fps single focus and built-in GPS with compass, altimeter and depth meter. The waterproof lenses are not compatible with non-waterproof cameras.

Lenses equipping mirrorless

Sony supplied 15 APS-C and 11 Full Frame E lenses for its NEX system, although there is some overlap in focal ranges between the two lines. Zeiss supplies some lenses for the Sony full frame A7 line, and only on the Sony A7 cameras currently in 2016 one can only have an auto focusing made by Zeiss lens on a Sony mirrorless, the full frame "Batis" line of lenses. A7 lenses branded "Zeiss" with auto focus are made under license not directly by Zeiss. The Micro Four Thirds System, shared by Olympus and Panasonic, currently offers 58 native lenses, with 3 wide zooms, 12 standard zooms, 11 telephoto zooms, 3 macro lenses, 14 single focal length zooms and one "3D" lens. Some recent so called "Pro" lenses are now being produced, which have better lens characteristics, ruggedness and weatherproofing - but weigh more and are larger. Also, there is an additional line of currently over 20 Cine lens for professional video, which can also be used for still photography, as Micro Four Thirds is used by Black Magic and Panasonic as Pro video lens standard, and Carl Zeiss produce 19 Cine lenses in Micro Four Thirds including zooms. Micro Four Thirds can also use both Panasonic and Olympus Zuiko Four Thirds lenses, with an adapter that allows aperture and focus operated from the camera, but phase equipped m43 cameras focus such lenses much better. Samsung has 11 different lenses available for its NX cameras (using an APS-C sensor). Nikon has 7 lenses available for the Nikon 1 system. Canon introduced two EF-M lenses alongside the EOS M. The Pentax K-01 can use all existing K-mount lenses, but because it lacks an aperture coupling, pre-1983 lenses (i.e., original K and K_F) require stop-down metering. Many lens adaptors exist but most do not support autofocus, although the Sony A7 mark II cameras can auto focus many Canon lenses, using various lens adapters, some better than others.

Sensor size

Nikon 1 V1 with Nikkor 10-30mm f/3.5-5.6 attached, and the Nikon 1 mount 30-110mm f/3.8-5.6 telezoom lens

(Details and figures of sensor sizes in Sensor size and angle of view and Image sensor format)

There is an inevitable trade-off between sensor size and compactness of the camera, due to the size of the lens required. Sensor size varies among mirrorless interchangeable-lens cameras. The Micro Four Thirds system uses the same size sensor as the 225mm² Four Thirds System (smallest among DSLRs but nine times the area of typical compact camera 25mm² 1/2.5" sensors), while the Fujifilm X cameras, Samsung NX cameras and Sony NEX cameras use a 65% larger APS-C size sensor of 370mm². The Canon EOS M uses a slightly smaller APS-C sensor with an area of 329mm². The Nikon 1 series and the Samsung NX mini use a smaller 115mm² 1" type sensor (13.2×8.8mm) with a 2.7 crop factor; the Pentax Q series initially used an even smaller compact camera 28.5mm² 1/2.3" image sensor with a crop factor of 5.5 and now uses a larger compact camera-type 1/1.7" sensor (43.3 mm²) with a crop factor of 4.55, while APS-C has a crop factor of 1.5, Canon APS-C has a crop factor of 1.6, and Micro Four Thirds MILCs have 2.0.

As of October 2015, the available full-frame 24×36 mm (864mm²) mirrorless cameras were five closely related Leica models (M9, M9-P, M-E, M Monochrom, and M, with the Monochrom shooting solely in black-and-white) and six Sony models from the NEX/mirrorless family (Alpha 7, 7R, 7S, 7-II, 7R-II and 7S-II). With the Leicas all being rangefinder cameras, they have optical viewfinders and thus can be called mirrorless. The Sony models, on the other hand, come equipped with electronic viewfinders. According to DxO Labs, all three newer Sony cameras have better sensor quality than the Leica rangefinders; the Leica M type 240 has only scored 84 for Sensor Overall, compared to 87, 90, 95 and 90 for the Sony A7S, A7, A7R and A7-II, and the A7R-II was described by DxO has being "The new high water mark in sensor dynamics" with a score of 98, respectively.

Benefits

Mirrorless cameras combine some of the benefits of both compact cameras and DSLRs. Compared to compact cameras, they offer the versatility allowed by interchangeable lenses. In addition to this, those mirrorless that are equipped with a large sensor also offer all the advantages associated with it.

Smaller size and lower weight

Smallest mirrorless camera Panasonic GM1 side by side with AA battery

Compared to DSLRs, mirrorless cameras are smaller (due to fewer parts, especially pentaprism or pentamirror) and sturdier (due to fewer moving parts).

Due to the lack of the mirror system, mirrorless cameras equipped by a large, DSLR-like sensor, can place lenses considerably closer to it (flange back distance) when compared to DSLRs. Short flange distance allows for high-quality lenses to be made smaller, cheaper, and lighter (wide-angle lenses in particular), and for wider apertures than dSLR lenses. Without a mirror, custom lenses with apertures as wide as f/0.7 have been created in small quantities, while ones as wide as f/0.95 are commercially available. However, current lens selection, though growing, is still relatively limited and expensive compared with the very well-developed DSLR lens market. Compact-style mirrorless cameras fitted with a thin "pancake" lens are pocketable, hence as portable as larger compact cameras, but when fitted with larger lenses they are less portable and not in general pocketable.

Compatibility with other lens mounts

The general principle is that a camera body with a given flange back distance can use lens mounts with longer flange back distances (thereby leaving room to insert an adapter) while still allowing focus to infinity without corrective optics. This is commonly a limitation with DSLR's, where DSLR lens mounts with a longer flange back distance cannot properly use lenses of mounts with a shorter distance (e.g. Nikon F mount cannot use lenses from Canon EF mount). In contrast, the shorter flange distance of mounts like micro-four-thirds allows for the use of most other lens systems using adapters (albeit usually without any auto-focus, aperture, or zoom). Additionally, many mirrorless camera systems allow easier usage of manual mode, due to the displayed image always being read from the sensor. An example would be focus peaking to assist in focus acquisition. For videography especially, it is useful to use legacy lenses with manual operation, and it allows one to buy discounted vintage lenses that otherwise wouldn't be usable on modern cameras.

Lower noise

Noise on shutter activation is quieter as there is no moving mirror.

Olympus PEN E-P2 for the Micro Four Thirds system

Drawbacks

Mirrorless share many of the limitations of compact cameras. These include:

No TTL optical viewfinder

The Olympus PEN E-PL5 features a tiltable LCD

The lack of through-the-lens optical viewfinder (TTL OVF) is a defining feature of MILCs, and also found on compact cameras – a TTL optical viewfinder requires an optical path from taking lens to viewfinder, hence an SLR design.

Lower cost mirrorless primarily use a rear LCD display for arm-level shooting, but some also feature an electronic viewfinder (EVF) for eye-level shooting. EVFs once suffered from a noticeable lag between the changes in the scene and the electronic viewfinder display, newer EVFs have improved their resolution and response times, with lag no longer being apparent. As a lower-priced option, some systems offer an optical viewfinder that is not TTL (as in a rangefinder), which suffers from parallax, particularly at short distances. EVFs allow overlay of complex real-time information such as focus peaking, under/overexposure "blinkies", AF regions, face tracking, digital zoom, image intensity adjustments with different light levels and histograms. Much higher resolution EVFs are now mature, and many mirrorless cameras now feature not only high resolution OLED viewfinders with no lag, but some offer more magnification than any DSLR provide. EVFs allow manual focusing technologies superior to optical viewfinders, such as the combination of digital zooming and focus peaking.

Contrast detection autofocus, and the introduction of phase detection autofocus system

Earlier mirrorless cameras have used contrast-detection autofocus (CDAF), which has generally been more accurate but (initially) slower than the phase detection autofocus systems found in DSLRs, often significantly, until July 2011 when the Olympus Pen E-P3 surpassed top range DSLRs in focusing speed for still shots. The improvement in speed has been achieved by reducing the time taken for the contrast-detection autofocus system to begin operation after half-pressing the shutter button, doubling the sensor readout speed to 120 frames per second (and 240 fps on Olympus cameras in continuous autofocus mode), and increasing the speed with which contrast detection routines operate. Although micros from Olympus and other manufacturers also have closed or leapfrogged this gap, there is still a gap in continuous autofocus accuracy and speed, and thus mirrorless are still not as good at photographing moving objects, notably in sports, as DSLRs.

Nikon's "1" system incorporates phase focusing together with contrast-detection autofocus, and Nikon claim it is as fast focusing for sport as their high end DSLRs. The Olympus OM-D E-M1 prosumer camera also offers phase detection autofocus in addition to contrast detection. One advantage of contrast detection autofocus is that, for still subjects, autofocus accuracy tends to be higher than with phase detect systems, as the camera uses the actual sensor output to determine focus. Therefore, CDAF systems are not prone to calibration issues such as front or back focus as can occur with phase detect systems.

Starting with the NEX-5R, released in November 2012, Sony has likewise introduced a hybrid or selectively used phase or contrast detection autofocus technology to their mirrorless cameras which produces significant improvement in autofocus speed. Sony also manufactures an adapter system for their NEX series mirrorless cameras that allows their SLT mirror technology to be mounted to NEX cameras by way of adapter. This adapter allows the E-Mount camera to use A-Mount lenses and brings real time phase detection auto focus for both still and video photography.

Canon introduced its dual-pixel autofocus technology in 2013 with its Canon EOS 70D DSLR. Dual-pixel AF enables the sensor's pixels to do phase-detection autofocus by themselves, and it is possible that the same technology could be used for mirrorless cameras as well. New sensors from Panasonic and Nikon and Sony are appearing with phase focus points in the sensor, notably the Sony A7R-II 's sensor has 399 phase detection points on its full frame sensor, which is far in excess of any DSLR phase points.

Compatibility with lenses from older systems

Panasonic M4/3 Camera are compatible with Olympus M4/3 Lens

Most mirrorless camera systems use a new lens mount, which is somewhat incompatible with existing SLR lenses – Micro Four Thirds (Panasonic and Olympus), NX-mount (Samsung), E-mount (Sony), 1-mount (Nikon) and EF-M mount (Canon). However the shorter flange distance means both that most older lenses can be used with an adapter, as well as the increasing number of native lenses designed and manufactured for the new mount. The only exception is the Pentax K-01, a mirrorless camera that accepts all legacy K-mount lenses without any adapter, but the consequence is that the K-01 is not as slim as the Sony NEX-7 or the Nikon 1 V1, although slimmer than one of the smallest SLRs on the market, the Pentax K-5.

As the largest investment in a system camera is the lenses, not the body, and lenses often last decades, changing a mount and rebuilding a lens collection is a significant investment. The use of a mirrorless system with adapters allows a DSLR user to adopt a new system without losing their prior investment in lenses. A particular advantage with Olympus's and now Sony's A7-II IBIS system, is that adding a lens without OIS will result in the lens gaining a stability system in the Olympus range. Also, older but good quality lens from discontinued systems that were considered useless have now increased in value by many times due to mirrorless owners using them on their cameras.

Recently manufacturer's of adapters have allowed electronic (2006 and onwards) Canon DSLR lenses to focus on Sony's A7R-II and A7-II cameras, both of which have phase focus points in their sensors. Some lens focus quickly, but not all, and in January 2016, longer focus lengths such as beyond 200mm focus inconsistently, and some lenses focus better than others. Some adapter manufacturers have introduced adapters that will focus electronic Nikon and Canon DSLR lenses and handle light issues on recent Panasonic m43 cameras, and it is possible more mirrorless manufacturers will assist in their mirrorless cameras being able to adapt DSLR lenses to their cameras. Issues due to different sensor sizes will effect the focal length of such adaptions, and also the depth of field will change if sensor sizes do not match the DSLR original sensor size.

Higher end mirrorless cameras feature focus peaking, which aids manual focusing used with third party lenses especially and focusing when videoing.

Adapters exist for legacy lenses although most do not support autofocus on mirrorless bodies. Micro Four Thirds has adapters for Arri PL, Arri S, C-mount, Canon EOS, Canon FD, Contax G, Contax/Yashica, Four Thirds, Konica AR (Hexanon), Leica M, Leica R, M38, M42, Minolta MC, Minolta MD, Minolta SR, Nikon F, Nikon G, Olympus OM, Olympus Pen F, Pentacon 6 / Kiev 66, Pentax K, Practica B, Rollei 35, Sony Alpha, T2, and Tamron Adaptall II mounts. The Sony E-mount has an adapter for the older Minolta A mount, Four Thirds, Canon FD, Leica M, M42, Nikon, Olympus OM, Minolta, Pentax K, and C mounts. The Nikon 1 series has an adapter for the company's F-mount, and the Canon EOS M has an adapter for that company's EF-S mount, which also accepts EF lenses. However, part of the benefit of MILCs is that newer, smaller lenses can be used; to realize these benefits, either new lenses or lenses for short flange distance legacy mounts, such as those used on rangefinder cameras, are required.

A Sony NEX 6 (camera on the left) using a DSLR lens via an adaptor

This can be compared with the situation for APS-C sized DSLRs, where most compatible lenses are designed for the larger 35mm cameras so are larger and heavier than necessary with inappropriate focal lengths, though a few specific Canon EF-S and Nikon DX lenses are designed to cover only the smaller imaging circle required for the smaller sensor, reducing lens size and manufacturing cost. However, lens design is compromised as they maintain the same mount distance to the sensor in order to provide compatibility with lenses designed for the larger 35mm sensor size.

This drawback, however, is somewhat balanced by the fact that some mirrorless cameras are small and light enough to be aimed at the "point-and-shoot" market where users are satisfied with the kit lens or an all-around "super-zoom", while other cameras in the same system are fully featured and designed for professional use encouraging the user to build a large system around their cameras.

For manufacturers, this strategy eliminates price competition for their new lenses from second-hand legacy lenses.

Systems comparison

System	Notable models	Lens mount	Sensor size	Stabilization	Throat diameter	Flange focal distance	Focus system	35mm equiv multiplier	Release date
Canon EOS M	Canon EOS M, Canon EOS M2, Canon EOS M3	Canon EF-M	22.3 × 14.9 mm APS-C	Lens-based	47 mm	18 mm	Hybrid Contrast-detection/Phase detection autofocus	1.6	October 2012
Fujifilm XF	Fujifilm X-Pro1, Fujifilm X-T1, X-A1, X-M1, X-E1, X-A2, X-E2, X-T10	Fujifilm X-mount	23.6 × 15.6 mm APS-C	Lens-based	44 mm	17.7 mm	Hybrid Contrast-detection/Phase detection autofocus on X-T1, X-E2; Contrast-detection autofocus on other models	1.5	January 2012
Leica M (rangefinder camera)	Leica M8, M9, M9-P, M Monochrom, M-E, M; Epson R-D1, R-D1s, R-D1x, R-D1xG	Leica M-mount	35.8×23.9 mm full-frame (M9, M9-P, M Monochrom, M-E, and M), 27×18 mm half-frame (M8), 23.7×15.6 mm pseudo–APS-C (R-D1)	none	44 mm	27.80 mm	Rangefinder	1.0	March 2004 (R-D1)
Micro Four Thirds system	Panasonic Lumix DMC-G1, G10, G2, G3, GH1, GH2, GH3, GF1, GF2, GF3, GX1, GX7 Olympus PEN E-P1, E-P2, E-P3, E-PL1, E-PL2, E-PL3, E-PM1, OM-D E-M5, E-PL5, OM-D E-M1	Micro Four Thirds	17.3×12.98 mm 4/3	Lens-based (Panasonic); In body (Olympus) Olympus EM-5 1st 5 axis stability system versus traditional 2 axis	~38 mm	20 mm	Contrast-detection autofocus on most bodies; hybrid contrast-detection/phase detection autofocus on Olympus OM-D E-M1	2.0	October 2008 (G1)
Nikon 1	Nikon 1 J1, V1, J2, V2, J4, V3, J5	Nikon 1 mount	13.2 × 8.8mm 1" Nikon CX	Lens-based		17 mm	Hybrid Contrast-detection/Phase detection autofocus	2.7	October 2011
Pentax K	Pentax K-01	Pentax K mount	23.6 × 15.6 mm APS-C	Sensor-based		45.46 mm	Contrast-detection autofocus	1.53	February 2012
Pentax Q	Pentax Q, Q10, Q7, Q-S1	Q-mount	6.17×4.55 mm (1/2.3") for Q and Q10 7.44×5.58 mm (1/1.7") for Q7	Sensor-based	38 mm	9.2 mm	Contrast-detection autofocus	5.5 (appx), Q and Q10 4.6 (appx), Q7	June 2011
Ricoh GXR	Ricoh GXR	Sealed interchangeable sensor lens unit system, and Leica M-mount	Depends on each sealed interchangeable sensor lens unit: APS-C, 1/1.7", 1/2.3"	depends	—	—	Contrast-detection autofocus for sealed camera units, manual focus (display-assisted) for Leica M mount unit	1.5	November 2009
Samsung NX	Samsung NX10, NX100, NX200, NX20, NX300, NX30, NX500, NX1	Samsung NX-mount	23.4 × 15.6 mm APS-C	Lens-based	42 mm	25.5 mm	Hybrid Contrast-detection/Phase detection autofocus	1.53	January 2010
Sony α NEX	NEX-3, NEX-5, NEX-5N, NEX-6, NEX-7 (still cameras), NEX-VG10 (video camera)	Sony E-mount	23.4 × 15.6 mm APS-C	Lens-based	46.1 mm (1.815 inch)	18 mm	Contrast-detection autofocus (earlier models), Phase and Contrast (newer models)	1.5	June 2010
Sony α ILCE	A7, A7R, A7S, A7-II, A7R-II, A7S-II, α6300, α6000, α5000, α3000	Sony FE-mount (full-frame) Sony E-mount (cropped)	35.8×23.9 mm full-frame (Alpha 7, 7R, 7S, 7-II, 7R-11 and 7S-II) 23.4 × 15.6 mm APS-C (Alpha x000)	Depends (Lens based although A7-II, A7R-II and A7S-II have 5 axis IBIS and can utilise lens and IBIS at same time)	46.1 mm (1.815 inch)	18 mm	Contrast-detection autofocus, Phase & Contrast (A7,A7-II, α6000)	1 (α7x), 1.5 (αx000)	October 2013

History

Panasonic Lumix DMC-G1

The category started with Epson R-D1 (released in 2004), followed by Leica M8 (released September 2006, which isn't actually a "mirrorless" but a rangefinder camera, a system of focussing dating back to 1933 and the release of the Leica III, itself a development of the 1932 Leica II) and then the Micro Four Thirds system, whose first camera was the Panasonic Lumix DMC-G1, released in Japan in October 2008.

A more radical design is the Ricoh GXR (November 2009), which features, not interchangeable lenses, but interchangeable lens units – a sealed unit of a lens and sensor. This design is comparable but distinct to MILCs, and has so far received mixed reviews, primarily due to cost; As of 2012 the design has not been copied.

Following the introduction of the Micro Four Thirds, several other cameras were released in the system by Panasonic and Olympus, with the Olympus PEN E-P1 (announced June 2009) being the first in a compact size (pocketable with a small lens). The Samsung NX10 (announced January 2010) was the first camera in this class not using the Micro Four Thirds system – rather a new, proprietary lens mount (Samsung NX-mount). The Sony Alpha NEX-3 and NEX-5 (announced May 14, 2010, for release July 2010) saw the entry of Sony into the market, again with a new, proprietary lens mount (the Sony E-mount), though with LA-EA1 and LA-EA2 adapters for the legacy Minolta A-mount.

In June 2011, Pentax announced the 'Q' mirrorless interchangeable lens camera and the 'Q-mount' lens system. The original Q series featured a smaller 1/2.3 inch 12.4 megapixel CMOS sensor. The Q7, introduced in 2013, has a slightly larger 1/1.7 inch CMOS sensor with the same megapixel count.

In September 2011, Nikon announced their Nikon 1 system which consists of the Nikon 1 J1 and Nikon 1 V1 cameras and lenses. The V1 features an electronic viewfinder.

The Fujifilm X-Pro1, announced in January 2012, is currently the only non-rangefinder mirrorless with an in-built optical viewfinder. Its hybrid viewfinder overlays electronic information, including shifting framelines to compensate for parallax.

Comparisons

Mirrorless can be seen as replacing or supplementing the existing categories of compacts, DSLRs, and bridge cameras. Most often, a mirrorless (either compact-style or DSLR-style) can be a step up from a compact, instead of or on the way to DSLRs. Alternatively, a compact-style mirrorless can be a more portable supplement to a DSLR, instead of a compact camera. More rarely, a mirrorless can be a third camera, in addition to a DSLR and compact – not portable enough for everyday (always carried) use, but not as serious as a dedicated DSLR, instead being relatively portable, for walking around and occasional shooting. They are less frequently compared to bridge cameras, as despite filling a similar intermediate niche, they differ significantly in design.

Compared to high-end compact cameras compact-style mirrorless equipped with a large sensor provide better image quality. Their lens systems, though, make them considerably bulkier (zoom lenses in particular). Small-sensor mirrorless have no image-quality advantage over high-end compacts, but they offer more versatility (due to interchangeable lenses).

DSLR-style mirrorless are in most respects very similar to DSLRs, though DSLR-style mirrorless are significantly smaller and light, most notably in being thinner, and also quieter due to lack of flipping mirror, are more video capable and their LCD screen basis provides a uniform interface compared to DLSRs. Mirrorless lenses are smaller than comparable DSLR lenses, but current Mirrorless lens selection is much more limited and relatively expensive, but most MILC cameras can use DSLR lenses by adding a US$40 adapter.

Higher end mirrorless cameras are appearing with electronic first curtain shutters, which aids in low light photography. Focus tracking technology has advantages compared to DSLRs because the computer using on board phase sensors tracks the high resolution image from the sensor rather than RGB low resolution data that phase DSLRs rely on.

Bridge cameras

Mirrorless occupy a similar niche to bridge cameras, being intermediate between compacts and DSLRs, but in many respects make opposite design decisions, and complement rather than replace each other: with rare exception, bridge cameras use a small sensor, a variable superzoom fixed lens, and DSLR-style body, while mirrorless use a large sensor, interchangeable lenses (with lower zoom factor), and either a compact-style or DSLR-style body. The difference is because a small sensor can be sufficiently provided for by a superzoom lens, which can hence be fixed, and since superzoom lenses are relatively large, there is little benefit in having a compact body. The small sensors on bridge cameras also boast an extremely high crop factor (typically above 5.0), thus allowing such cameras to achieve zoom ranges that are physically impossible on DSLRs and cameras utilizing larger sensors. This trait alone makes a bridge camera much more versatile than DSLRs and mirrorless whose lens lineups are usually not capable of achieving anything more than the 35mm focal length equivalent of 500mm; in contrast, most bridge cameras usually ship with lenses that are capable of providing a 35mm focal length equivalent of more than 600mm, with some cameras even capable of exceeding 800mm: Nikon's Coolpix P510, for example, has a 35mm equivalent zoom range of 24–1000mm.

Large sensors, by contrast, are more demanding on lenses and hence interchangeable lenses are generally used to cover the range (though compare fixed-lens Sigma DP1 and Leica X1); smaller lenses allow an overall small camera, hence the possibilities of compact-style mirrorless, while DSLR-style bodies are still easier to use for dedicated photography.

Two exceptions to the rule that bridge cameras have small sensors are Sony models that feature large sensors and fixed lenses—the now-discontinued Cyber-shot DSC-R1, with an APS-C sensor and a zoom lens; and the current Cyber-shot DSC-RX1, with a full-frame sensor and a prime lens. The current Canon PowerShot G1 X features the same combination as the DSC-R1.

Market

Compact-style mirrorless with pancake lenses generated significant excitement in the photographer community, as they finally provided a pocketable digital camera with a large sensor (hence high image quality). DSLR-style Mirrorless, and compact-style Mirrorless with larger lenses have also generated interest, and with full frame mirrorless with internal IBIS providing lighter and more compact still and video capabilities Mirrorless is offering new possibilities to the DSLR concept.

Beyond the interest to consumers, mirrorless has created significant interest in camera manufacturers, having potential to be an alternative in the high-end camera market. Significantly, mirrorless has fewer moving parts than DSLRs, and are more electronic, which plays to the strengths of electronic manufacturers (such as Panasonic, Samsung and Sony), while undermining the advantage that existing camera makers have in precision mechanical engineering. Sony's entry level full frame mirrorless A7MkII camera has a 24MP 5 axis stabilised sensor yet is more compact and lower in cost than any full frame sensor DSLR.

Nikon announced the Nikon 1 series on September 21, 2011 with 1" sensor. It is a high-speed mirrorless which according to Nikon featured world's fastest autofocus and world's fastest continuous shooting speed (60 fps) among all cameras with interchangeable lenses including DSLRs. Canon was the last of the major makers of DSLRs, announcing the Canon EOS M in 2012 with APS-C sensor and 18mm registration distance similar to the one used by NEX.

In a longer-term Olympus decided that mirrorless may replace DSLRs entirely in some categories with Olympus America's DSLR product manager speculating that by 2012, Olympus DSLRs (the Olympus E system) may be mirrorless, though still using the Four Thirds System (not Micro Four Thirds).

Panasonic UK's Lumix G product manager John Mitchell while speaking to the Press at the 2011 "Focus on Imaging" show in Birmingham, reported that Panasonic "G" camera market share was almost doubling each year, and that UK Panasonic "G" captured over 11% of all interchangeable camera sales in the UK in 2010, and that UK "CSC" sales made up 23% of the Interchaneable lens market in the UK, and 40% in Japan.

As of May 2010, interchangeable-lens camera pricing is comparable to and somewhat higher than entry-level DSLRs, at US$550 to $800, and significantly higher than high-end compact cameras. As of May 2011, interchangeable-lens camera pricing for entry mirrorless appears to be lower than entry-level DSLRs in some markets e.g. the U.S.

• 
  Pentax Q
• 
  Ricoh GXR
• 
  Samsung NX10

Sony announced 2011 sales statistics in September 2012, which showed that mirrorless had 50% of the interchangeable lens market in Japan, 18% in Europe, and 23% worldwide. Since that time Nikon has entered the mirrorless market, amongst other new entries.

In down-trend world camera market, mirrorless also suffer, but not much and can be compensated with increase by about 12 percent of 2013 sales in popular mirrorless domestic (Japan) market. However, mirrorless has taken longer catch on in Europe and North America—according to Japanese photo industry sources, mirrorless made up only 11.2% of interchangeable-lens cameras shipped to Europe in the first nine months of 2013, and 10.5% in the U.S. in the same period. Also, an industry researcher determined that Mirrorless sales in the U.S. fell by about 20% in the three weeks leading up to December 14, 2013—which included the key Black Friday shopping week; in the same period, DSLR sales went up 1%.

2015 statistics show that overall camera sales have fallen to one third of those of 2010, due to compact cameras being substituted by camera capable mobile phones. This means that overall share of camera sales is seeing ILC market share increasing, with world volumes showing ILC having 30% ofr overall camera sales, of which DSLR had 77% and mirrorless 23%. In the Americas in 2015, DSLR annual sales in dollars are now falling by 16% aper annum, while mirrorless sales over the same 12-month period have increased by 17%. Hence the Mirrorless market share of interchangeable lens cameras has more than doubled in two years.

References

• Fairlie, Rik (April 7, 2010). "A Digital Camera That Swaps Lenses, Priced to Please". The New York Times. ISSN 0362-4331. Retrieved May 16, 2010.