The mirrorless interchangeable-lens camera (MILC) is a class of digital system cameras. This type of camera provides an interchangeable lens mount. They do not have a mirror reflex optical viewfinder. MILC cameras comprise 5% of total camera shipments.
After a few years without a well-defined classification, many specialized pages and also major manufacturers are adopting the term DSLM or simply Mirrorless. This standardization in the classification of this group of cameras has been a growing need, since DSLM or Mirrorless has been incorrectly included in the category Digital Compact Cameras. Compact cameras have tiny sensors and do not exchange lenses. Being compact is a quality of DSLM and one of its strongest attributes, which has attracted a growing number of adherents to the system. The DSLM has been manufactured with complete various sensor sizes from 1/2.3", 1/1.7", 1", Micro 4/3, APS-C and Full Frame sensors. And after 2013 DSLR downturn, in early 2014 many camera manufacturers, including Nikon released many MILC including the lenses.
Various alternative names exist including: compact system camera (CSC), mirrorless system camera (MSC), digital single lens mirrorless (DSLM), digital interchangeable-lens system camera, and electronic viewfinder with interchangeable lens (EVIL)
As of 2014, several MILC 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 MILCs; Samsung NX-mount for Samsung MILCs; Sony E-mount for Sony MILCs; Nikon 1-mount for Nikon MILCs; Pentax Q mount for Pentax small-sensor MILC (Pentax Q); K-mount for both Pentax DSLRs and Pentax large-sensor MILC; X-mount for Fujifilm MILCs; and Canon EF-M mount for Canon MILCs. (Sony's full-frame MILCs, introduced in late 2013, use the same E-mount as the company's APS-C MILCs, but require "FE" lenses for full-frame coverage.)
Types of digital cameras
Several types of digital cameras are available on the market, including:
- DSLR 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.
MILC types
MILC cameras feature lens interchangeability. The size of sensors in MILCs varies. Two styles of MILCs exist, compact and DSLR-like. Compact-style ones are approximately the size of larger compact cameras. DSLR-style MILCs overlap with entry-level DSLRs, providing a contoured body and extensive features, like DSLRs, but still in a significantly smaller and lighter body.
Not all MILCs 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 MILC: 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 MILC, is slightly smaller than the Sony NEX series, but also has an APS-C sensor.
In 2013, Sony announced a transition away from the NEX brand name, with future cameras in that family to be called Alpha ILCE; three MILCs in the renamed family, the Alpha 7, 7R and 7S, are full-frame.
3D MILC
Using a prime lens â€" described as a 45mm f/1.8 2D/3D lens â€" the Samsung NX300 can take 2D stills, 3D stills or Full HD movies (see Stereo camera#Use of one camera and one lens).
Waterproof MILC
In September 2013, Nikon launched the AW1, the world's first waterproof MILC with capability of 15 meters underwater, 1" sensor size, 14.2MP, Full HD video, 15fps continuous AF or 60fps single focus and built-in GPS with compass, altimeter and depth meter. The waterproof lenses are not compatible with non-waterproof cameras.
Lenses equipping MILCs
Sony supplied 10 E lenses for its NEX system (adopting an APS-C sensor). The Micro Four Thirds System, shared by Olympus and Panasonic, currently offers 34 native lenses (including 17 by Panasonic and 12 by Olympus, not counting versions of the same lens; e.g., all three versions of the 14-42mm lens are counted together as one lens). 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 KF) require stop-down metering. Many lens adaptors exist but most do not support autofocus.
Sensor size
(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 November 2014, the only 24×36 mm (864mm2) MILCs 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 three Sony models from the NEX/ILCE family (Alpha 7, 7R, and 7S). With the Leicas all being rangefinder cameras, they have optical viewfinders and thus can be called MILCs, but not EVILs. 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 and 95 for the Sony A7S, A7 and A7R, respectively.
Benefits
MILCs 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 MILCs which are equipped with a large sensor also offer all the advantages associated with it.
Smaller size and lower weight
Compared to DSLRs, MILCs 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, MILCs 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 MILCs 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). 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.
Drawbacks
MILCs share many of the limitations of compact cameras. These include:
No TTL optical viewfinder
The lack of through-the-lens optical viewfinder (TTL OVF) is a defining feature of MILCs, and also found on compact cameras â€" a TTL optical viewfinder requires an optical path from taking lens to viewfinder, hence an SLR design.
MILCs primarily use a rear LCD display for arm-level shooting, but some also feature an electronic viewfinder (EVF) for eye-level shooting. Some EVFs suffer from a noticeable lag between the changes in the scene and the electronic viewfinder display, however some 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.
Contrast detection autofocus, rather than phase detection autofocus system
Thus far, most MILC cameras have used Contrast-based AF, which has generally been more accurate but (initially) slower than the phase-based AF 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 MILCs are still not as good at photographing moving objects, notably in sports, as DSLRs.
Nikon's "One" 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 phase/contrast detection autofocus technology to their MILC cameras which produces significant improvement in autofocus speed. Sony also manufactures an adapter system for their NEX series MILC 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 and it is widely expected that the same technology could be useful for mirrorless cameras as well. Dual-pixel AF enables the sensor's pixels to do phase-detection autofocus by themselves.
Compatibility with lenses from older systems
Most MILC camera systems use a new lens mount, which is somewhat incompatible with existing SLR lenses â€" 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 MILC 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 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 MILC owners using them on their cameras.
Adapters exist for legacy lenses although most do not support autofocus on MILC 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.
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 MIL 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
History
The category started with Epson R-D1 (released in 2004), followed by Leica M8 (released September 2006) 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 â€" 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 â€" 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 1/2.3Â inch 12.4 megapixel CMOS sensor. The Q7, introduced in 2013, has a slightly larger 1/1.7Â 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 MILC with an in-built optical viewfinder. Its hybrid viewfinder overlays electronic information, including shifting framelines to compensate for parallax.
Comparisons
MILCs can be seen as replacing or supplementing the existing categories of compacts, DSLRs, and bridge cameras. Most often, a MILC (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 MILC can be a more portable supplement to a DSLR, instead of a compact camera. More rarely, a MILC can be a third camera, in addition to a DSLR and compact â€" 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 MILCs equipped with a large sensor provide better image quality. Their lens systems, though, make them considerably bulkier (zoom lenses in particular). Small-sensor MILCs have no image-quality advantage over high-end compacts, but they offer more versatility (due to interchangeable lenses).
DSLR-style MILCs are in most respects very similar to entry-level DSLRs, though DSLR-style MILCs are significantly smaller and light, most notably in being thinner, and also quieter due to lack of flipping mirror. MILC lenses are smaller than comparable DSLR lenses, but current MILC lens selection is much more limited and relatively expensive, but most MILC cameras can use DSLR lenses by adding a $40 adapter.
Bridge cameras
MILCs 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 MILCs 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 MILCs 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 MILCs, 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 lensesâ€"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 MILCs with pancake lenses have generated significant excitement in the photographer community, as they finally provide a pocketable digital camera with a large sensor (hence high image quality). DSLR-style MILCs, and compact-style MILCs with larger lenses have also generated interest, but more as refinements on the overall DSLR concept, rather than creating new possibilities.
Beyond the interest to consumers, MILCs have created significant interest in camera manufacturers, having potential to be a disruptive technology in the high-end camera market. Significantly, MILCs have 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.
Nikon announced the Nikon 1 series on September 21, 2011 with 1" sensor. It is a high-speed MILC 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 MILCs 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 MILCs appears to be lower than entry-level DSLRs in some markets e.g. the USA.
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% world wide. Since that time Nikon has entered the Mirrorless market, amongst other new entries.
In down-trend world camera market, MILC also suffer, but not much and can be compensated with increase by about 12 percent of 2013 sales in popular MILC domestic (Japan) market. However, MILCs have so far failed to catch on in Europe and North Americaâ€"according to Japanese photo industry sources, MILCs made up only 11.2% of interchangeable-lens cameras shipped to Europe in the first nine months of 2013, and 10.5% in the US in the same period. Also, an industry researcher determined that MILC sales in the US fell by about 20% in the three weeks leading up to December 14, 2013â€"which included the key Black Friday shopping week; in the same period, DSLR sales went up 1%.
See also
- Bridge camera
- Lens mount