Mirrorless electronic interchangeable lens Camera (MILC)

milc cameras

The MILC Mirrorless interchangeable lens camera . The MILC Interchangeable Lens system is an up and coming type of digital cameras, they fit in between between Compact Digital Camera and DSLR cameras. They characteristically employ large sensors similar in size to starter level DSLRs. As the name implies they have no mirror, feature interchangeable lenses, and offer DSLR picture quality in a substantially smaller camera size. Originally they were called "SLD" for single lens digital.

Mirrorless Entry level Cameras

 October, 2012 ✓


The purpose of MILC cameras is to provide high quality imaging in a smaller — and in some respects superior — body than in DSLR cameras. Prior to the introduction of MILC, digital cameras featured either a small sensor (in various body styles), or a large sensor in a DSLR body, with very rare exception (see exceptions, below), and one was faced with a sharp trade-off between small-but-poor-quality or high-quality-but-large. DSLR cameras provide high quality imaging, but use essentially the same design and lenses as existing film SLR cameras; micros by contrast represent a break from the legacy of cameras designed for film.

SLRs are defined by having a through the lens (TTL) optical viewfinder — light enters through the lens, enters a light box, reflects off a mirror, then reflects off a pentaprism (or pentamirror) and exits through an optical viewfinder. When a picture is taken, the mirror flips out of the way, and the light instead hits the imaging surface (film or digital sensor).

Micros dispense with these mechanisms: There is no flipping mirror, and accordingly no need for a bulky light box — or pentaprism — and accordingly no distinctive bulge on the top of the body. A digital display screen on the camera serves the dual purpose of an electronic viewfinder and status display for setting camera functions. Short of these mechanisms, micros can have significantly thinner and lighter bodies with fewer moving parts. Further, by placing the lens closer to the sensor, smaller (and accordingly cheaper and lighter) lenses can be used, which is particularly significant for wide-angle lenses. Thus, due to the absence of a light box and having smaller lenses, micros are significantly smaller and lighter than DSLRs.

Compact cameras (with small sensors) do not feature interchangeable lenses, as they do not require them: a small sensor can be well-served by a single superzoom lens, notably in digital bridge cameras; some bridge cameras do allow an additional, secondary lens, however. Small sensors however have relatively poor imaging in many situations, notably low light, due to the low quantity of light that hits the sensor.

For large sensors, while superzoom lenses exist, they are sufficiently inferior to more restricted lenses (prime or zoom) in criteria such as optical quality and weight that interchangeable lenses are featured on virtually all modern cameras with large sensors, so-called system cameras.


Situated between compact cameras and DSLRs, two main types of micros have developed: compact and DSLR-like. Compact-style micros are approximately the size of larger compact cameras and, particularly with pancake lenses, are pocketable to some degree (can fit in a pocket). DSLR-style micros overlap with entry-level DSLRs, providing a contoured body and extensive features, like DSLRs, but in a significantly smaller and lighter body.

Sensor size

Image Sensor Sizes

Sensor size varies, but is at the size of entry-level DSLR sensors — the Micro Four Thirds system uses the same sensor as the Four Thirds System (smallest among DSLRs but over 9× the size of compact sensors), while the cameras offered by Samsung and Sony use a 50% larger APS-C size sensor. As of 2010, no company has announced or released a full-frame micro.

There is some inevitable trade-off between sensor size and compactness of the camera, due to the size of the lens required, so how small a compact-style full-frame micro may be is unclear, though a full-frame DSLR-style micro is certainly possible.


MILCs combine many of the benefits of both compact cameras and DSLRs, in some respects being "the best of both worlds".

Compared to compact cameras, they offer a larger sensor (DSLR-size) and hence higher image quality, and generally include more features and controls.

Compared to DSLRs, they are smaller (due to fewer parts), sturdier (due to fewer moving parts), and in principle cheaper, though As of 2010, current pricing is in some cases higher than entry-level DSLRs.

Compact-style micros fitted with a thin "pancake" lens are pocketable, hence as portable as larger compact cameras, though when fitted with larger lenses they are less portable and not in general pocketable.

Digital viewfinder can help the photographer to compose and check focus in low light situations. Digital viewfinder can also zoom in and this way help to check focus.

A more far-reaching benefit is that eliminating the light box allows lenses to be closer to the sensor, allowing high-quality lenses to be made smaller, cheaper, and lighter, particularly for wide-angle lenses. However, current lens selection is limited and relatively expensive, compared with the very well-developed DSLR lens market.


Conversely, MILCs share many of the limitations of both compact cameras and DSLRs. These include:

no TTL optical viewfinder
The lack of TTL optical viewfinder (TTL OVF) is a defining feature of micros, and also found on compact cameras — a TTL optical viewfinder requires an optical path from lens to viewfinder, hence an SLR design or similar. If an TTL OVF is desired or required, DSLRs are the only viable option.

Micros primarily use a rear LCD display for arm-level shooting, but some also feature an electronic viewfinder (EVF) for eye-level shooting, or an optical viewfinder that is not TTL (as in a rangefinder), which hence suffers from parallax, particularly at short distances.

contrast detection autofocus, rather than phase detection autofocus system
Contrast-based AF is generally slower than the phase-based AF systems found in DSLRs, often significantly so, and thus micros are relatively poor at photographing moving objects, notably in sports. Some argue that contrast-based AF will speed up over time and become competitive with phase-based, but As of 2010 DSLRs have a significant advantage in this respect.

incompatibility with existing lenses
All extant micro formats use a new lens mount, which is incompatible with existing lenses — Micro Four Thirds (Panasonic and Olympus), NX Mount (Samsung), and E Mount (Sony). This means both that existing lenses cannot be used, and that relatively few lenses exist for these cameras at the time of their introduction, as new lenses must be designed and manufactured for the new mount.

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.

While adapters exist for legacy glass — Micro Four Thirds has adapter with Four Thirds, while the Sony E mount has an adapter for the older Minolta A mount — part of the benefit of micros is that newer, smaller lenses can be used, and thus to realize these benefits, new lenses are required.

This can be compared with the situation for APS-C sized DSLRs, where the Canon EF-S lens mount and Nikon DX lenses are specifically designed for the smaller sensor, and which feature lenses placed closer to the sensor due to smaller imaging circle, with similar benefits as for micros.


There is some ambiguity in classification, as this is an emerging category and design has not stabilized, so the precise defining characteristics are not agreed on, as reflected in different names for the category.

As a product category, this generally refers to new, entirely digital designs, rather than adaptations of designs from the film era with only the film replaced by a digital sensor. Thus, dispensing with the traditional optical viewfinder (as in the "MILC" term), at least in the core design, is generally seen as defining, but some designs include optional optical viewfinders, though not TTL.

Notably, whether the Leica M8 (and M9) and the Sigma DP1 (and, DP1S & DP2) should be included is unclear, as both of these feature large sensors in a mirrorless design, but differ in other respects – these are generally excluded.

For example, the Leica M8 is a rangefinder – a legacy design – and is essentially the same design as previous Leica film cameras. The Leica is also significantly more expensive (US $5,000+, compared to $500–$1,000 to the other cameras in this category), and in most camera discussions is considered a distinct category.

The Sigma DP1 is a new design and is very similar to compact-type micros, but features a fixed lens, and is generally considered a pioneering precursor, not precisely of this class. Similarly, the Leica X1 is a high-end fixed-lens camera, and not strictly comparable to micros.

Micros are sometimes distinguished as having an electronic viewfinder (rather than an optical), as in the MILC designation, but among the group of products, there are cameras with an additional see-through optical viewfinder (as can be added to the Olympus PEN E-P1 or the Leica X1), and products with an electronic/optical viewfinder (as can be found in the Panasonic Lumix DMC-G1). However, these optical viewfinders are not TTL, unlike the ones in SLRs.

Systems comparison

Models Lens mount Sensor size Flange focal distance Focus system
Canon EOS M
Canon EOS M
Canon EF-M
EF-EFS Adapter
22.3 × 14.9 mm APS-C 18 mm Hybrid Contrast-detection/Phase detection autofocus
Fujifilm X-Pro1, X-E1 Fujifilm X-mount 23.6 × 15.6 mm APS-C 17.7 mm Contrast-detection autofocus
Leica M
Leica M8, M9, M9-P, M Monochrom; Epson R-D1, R-D1s, R-D1x, R-D1xG
Leica M-mount 35.8×23.9 mm full-frame (M9, M9-P, and M Monochrom), 27×18 mm half-frame (M8), 23.7×15.6 mm pseudo–APS-C(R-D1) 27.80 mm Rangefinder

Micro Four Thirds system
Panasonic Lumix DMC-G1, G10, G2, G3, GH1, GH2, GH3, GF1, GF2, GF3, GX1 (still cameras), Panasonic AG-AF100 (video camera)

Olympus PEN E-P1, E-P2, E-P3, E-PL1, E-PL2, E-PL3, E-PM1 OM-D E-M5

Micro Four Thirds 17.3×12.98 mm 4/3 20 mm Contrast-detection autofocus
Nikon 1 J1, V1 Nikon 1 CX mount
Nikon Adapter
13.2 × 8.8mm 1" Nikon CX 17 mm Hybrid Contrast-detection/Phase detection autofocus
Pentax K-01 Pentax K mount 23.6 × 15.6 mm APS-C 45.46 mm Contrast-detection autofocus
Pentax Q Q10 Q-mount 6.17×4.55 mm (1/2.3") 99.2 mm Contrast-detection autofocus
Ricoh GXR Sealed interchangeable sensor lens unit system, and Leica M-mount Depends on each sealed interchangeable sensor lens unit: AAPS-C, 1/1.7", 1/2.3" — Contrast-detection autofocus for sealed camera units, manual focus (display-assisted) for Leica M mount unit
Samsung NX
Samsung NX10, NX5, NX100, NX11, NX200, NX20
Samsung NX-mount 23.4 × 15.6 mm APS-C 25.5 mm Contrast-detection autofocus
Sony α NEX
NEX-3, NEX-5, NEX-C3, NEX-5N, NEX-7 (still cameras), NEX-VG10 NEX-VG20 (video camera)
Sony E-mount 23.4 × 15.6 mm APS-C 18 mm Contrast-detection autofocus

A handful of rangefinder cameras support interchangeable lenses. Three digital rangefinders exist, they are the Epson R-D1 (APS-C-sized sensor), the Leica M8 (APS-H-sized sensor), both smaller than 35 mm film rangefinder cameras, and the Leica M9, which is a full-frame camera.


The category is generally taken to have started with the development of the Micro Four Thirds system, whose first camera was the Panasonic Lumix DMC-G1, which was released in Japan in October 2008.

Prior to this, the Leica M8 (released September 2006) is a mirrorless digital camera with a large sensor and interchangeable lenses, but is generally considered distinct, both because it uses an existing film design (a rangefinder, rather than the more common SLR design used in DSLRs) and due to its high price (in the neighborhood of $5,000, rather than around $500–$1,000 for initial Micros). The Sigma DP1 (released spring 2008) is also mirrorless with a large sensor, this time in a compact body, but with a fixed lens, as is the Leica X1 (at US $2,000); these may be classed as "high-end compact", but are generally considered separate.

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 comparabale but distinct to micros, and has so far received mixed reviews, primarily due to cost; As of 2010 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 NEX3 & NEX5 (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 an adapter for the legacy Minolta A-mount.

As of September 2012, other manufacturers (Canon, Kodak, Fuji, etc.) have also announced or released cameras in this class.


Micros can be seen as replacing or supplementing the existing categories of compacts, DSLRs, and bridge cameras. Most often, a micro (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 micro can be a more portable supplement to a DSLR, instead of a compact camera. More rarely, a micro 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 different significantly in design.

Compared to high-end compact cameras, compact-style micros provide a significantly larger sensor and hence image quality, and are bulkier, at times significantly so. Compact cameras can be quite small, as in the ultracompact camera category, while micros (particularly with large sensors) are limited in how small they can be – the Sony NEX-5 being the smallest example, with further reduction limited by the size of its mount.

DSLR-style micros are in most respects very similar to entry-level DSLRs, though DSLR-style micros are significantly smaller and light, most notably in being thinner, and also quieter due to lack of flipping mirror. Micro lenses are smaller than comparable DSLR lenses, but current micro lens selection is very limited and relatively expensive.

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 fixed superzoom lens, and DSLR-style body, while micros 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. 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 micros, while DSLR-style bodies are still easier to use for dedicated photography.

One exception to the rule that bridge cameras have small sensors is the Sony Cyber-shot DSC-R1, now discontinued, which featured a large sensor and a fixed lens.


As of 2012, MILC has become the mostly widely-accepted term for this class of cameras. The most used technical term is mirrorless interchangeable lens camera, while Panasonic and Olympus call them New Generation System Cameras.

An alternative and less-precise term is MILC camera, (Electronic Viewfinder with Interchangeable Lens). The term was coined by Charlie Davis in August 2007, then popularized via a October 2007 posting repeated on a Wired blog.

The term "hybrid cameras", is an alternative name, and is widely used by retailers and customers seem to adopt that term. The name origins from looking at the cameras as a cross breed, and a best of two worlds, kind of camera.

The term Micro Four Thirds is sometimes used for the entire class, not just MFT system cameras, or alternative abbreviated to Micro, as in "Sony has just released a Micro."


Compact-style micros 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 micros, and compact-style micros 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, micros have created significant interest in camera manufacturers, having potential to be a disruptive technology in the high-end camera market. Significantly, micros have fewer moving parts than DSLRs, and are more electronic, which plays to the strengths of electronic manufacturers (such as Samsung and Sony), while undermining the advantage that existing camera makers have in precision mechanical engineering.

The main makers of DSLRs, Canon & Nikon, have not announced any micro cameras, though it is widely believed that they are developing some, and some officials have made statements to that effect.

Longer-term, micros may replace DSLRs entirely in some categories or among some manufacturers, 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).

As of May 2010, micro pricing is comparable and somewhat higher than entry-level DSLRs, at US$550 to $800, and significantly higher than high-end compact cameras.

Four Thirds and Micro Four Thirds Lens Adapters
Four Thirds and Micro Four Thirds Lens AdaptersHave an old lens you want to mount on your new Four Thirds System Camera? Now you can adapt Leica, Olympus, Nikon, Panasonic, Voigtlander and Four Thirds Lenses to Micro Four Thirds Cameras and Four Thirds Cameras. May 15, 2011 ✓

See also


  1. http://www.pcpro.co.uk/reviews/digital-cameras/359470/sony-nex-5/2
  2. Davis, Charlie. "4:3 Camera Project". Archived from the original on 2007-10-22. http://web.archive.org/web/20071022061738/http://here-ugo.com/BridgeBlog/?page_id=27
  3. MILC camera: Not Actually Evil, Wired
  4. Olympus E system mirrorless in two years. Probably., Monday 22nd February 2010, Damien Demolder
  5. Fairlie, Rik (2010-04-07). "A Digital Camera That Swaps Lenses, Priced to Please". The New York Times. ISSN 0362-4331. http://www.nytimes.com/2010/04/08/technology/personaltech/08basics.html.

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